QL391. N4 B51 blfhr C.l G351266 University of Ghana http://ugspace.ug.edu.gh VECTOR SPECIES OF GUINEA WORM IN WEST AKIM DISTRICT OF GHANA, AND THE EVALUATION OF ABATE AS A CYCLOPSCIDE. BY LANGBONG BIMI B. Sc. (Hons.), Legon. A THESIS SUBMITTED TO THE ZOOLOGY DEPARTMENT, UNIVERSITY OF GHANA, IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF M. Phil. DEGREE IN ZOOLOGY, (APPLIED PARASITOLOGY OPTION). SEPTEMBER, 1996. University of Ghana http://ugspace.ug.edu.gh DECLARATION This research work was conducted by me as presented, under the supervision of Prof. J. K. M. Hodasi of the Zoology Department, University of Ghana, Legon. LANGBONG BIMI (Student) PROF. J. K. M. HODASI (Supervisor) University of Ghana http://ugspace.ug.edu.gh i DEDICATION. In ever loving memory of my late sister Miss Joyce Feikandin Bimi. May your soul rest in perfect peace. University of Ghana http://ugspace.ug.edu.gh ACKNOW LEDGM ENT Many people contributed and assisted in the preparation and completion of this work. I am particularly indebted to Prof. J. K. M. Hodasi, under whose profound inspiration, encouragement, guidance and resourceful supervision this project was carried out. Special words of gratitude and appreciation are also reserved for Dr. Chris Gordon and Mr. Joseph Amakye, both members of my supervisory committee, for their advice, constructive suggestions, criticisms and encouragement. The moral and logistic support provided by my Head of Department, Prof. D. S. Djangmah for the field work is indeed deeply appreciated. The selfless assistance given me by the coordinators of the Guinea Worm Eradication Programme of West Akim District, especially Mr. Buadu can neither be quantified nor costed, I therefore say a big thank you. I also wish to express my heart felt gratitude to Professor M. Dakubu, Drs. William Phillips and Frederick Phillips as well as Mr. Stephen Asunka for assisting me in various ways to type out the manuscript. University of Ghana http://ugspace.ug.edu.gh iii TABLE OF CONTENTS Declaration Dedication........................................................................................................................................................1 Acknowledgement.............................................................................................................................................. 11 Table of contents........................................................................................................ ............................... Abstract........................................................................................................................................................Vil1 List of acronyms.......................................................................................................................................... *x List of tables................................................................................................................................................... x List of figures...............................................................................................................................................xii List of plates...............................................................................................................................................xiii CHAPTER 1. 1.0 INTRODUCTION.............................................................................................................................. 1 CHAPTER 2. 2.0 LITERATURE REVIEW ............................................................................................................. 6 2.1.0 History o f Dracunculus medinensis................................................................................................ 6 2.2.0 Taxonomy and Life Cycle of D. medinensis.................................................................................. 8 2.2.1 Taxonomy........................................................................................................................................... .. 2.2.2.0 Life-Cycle........................................................................................................................................ .. 2.2.2.1 Discovery.................................................................................................. c) University of Ghana http://ugspace.ug.edu.gh 2.3.0 Taxonomy, biology and ecology of Cyclops..............................................................................15 2.4.0 Epidemiology and importance of Guinea worm disease.................... ................................ .....19 2.4.1 Epidemiology.................................................................................................................................. 19 2.4.2 The socio-economic importance o f Dracunculiasis................................................................... 20 2.4.3 Endemicity of GWD. in Ghana......................................................................................................21 2.5.0 Control and Prevention of Dracunculiasis...................................................................................22 2.5.1 Health Education (HE)....................................................................................................................24 2.5.2 Provision o f Safe Drinking Water................................................................................................. 25 2.5.3 ’’Treatment" o f Dracunculiasis.......................................................................................................25 2.5.4 Vector Control.................................................................................................................................28 2.6.0 Study Objectives.............................................................................................................................3 0 CHAPTER 3. 3.0 MATERIALS AND METHODS 31 3.1.0 Field Studies.................................................................................................................................... 31 3.1.1 Study locale and features of sampling sites.................................................................................3 1 3.1.2 Pond Morphometry....................................................................................................................32 3.1.3 Estimation of Cyclops density...................................................................................................... 32 3.1.4 Retrospective Study on GWD. in the Study area........................................................................33 3.2.0 Laboratory Work........................................................................................................ 33 University of Ghana http://ugspace.ug.edu.gh 3.2.1 Identification of Cyclops species................................................................................................. 33 3.2.2 Investigation of species specific toxicities..................................................................................34 3.2.3 Pond culture o f Cyclops..................................................................................................................35 3.2.4 Toxicity Tests................................................................................................................................... 36 CHAPTER 4. 4.0 R E SU L T S 39 4.1.0 Field studies................................................................ ...................................................................39 4.1.1 Pond Morphometry....................................................................................................................... 39 4.1.2 seasonal variation in Cyclops count............................................................................................39 4.1.3 Prevalence of GWD. in the study area....................................................................................... 40 4.1.3.1 Tiokrom..............................................................................................................................40 4.1.3.1a Incidence by age and sex................................................................................................ 40 4.1.3.1b Incidence by occupation..................................................................................................40 4.1.3.1c Monthly variation in prevalence.................................................................................... 41 4.1.3. Id Site of worm emergence.................................................................................................41 4.1.3.2 Dzakpatra.......................................................................................................................... 41 4.1.3.2a Incidence by age and sex................................................................................................41 4.1.3.2b Incidence by occupation.................................................................................................. 41 4.1.3.2c Monthly variation in prevalence....................................................................................42 4.1.3.2d Site of worm emergence................................................................................................. 4 2 V University of Ghana http://ugspace.ug.edu.gh 4.1.3.3 Mepom............................................................................................................................................ 4.1.3.3a Mepom (Mataligu section).................................................................*............... *...........42 4.1.3.3b Mepom (Kwesi Acheampong section)................................................... ...................... 42 4.2.0 Socio-cultural aspects of Dracunculiasis................................................................................... 43 4.2.1 Beliefs, attitudes and values......................................................................................................... 43 4.3.0 Laboratory work.............................................................................................................................44 4.3.1 Toxicity tests.................................................................................................................................. 44 4.3.1.1 Lethal concentrations.................................................................................................................... 45 4.3.1.2 Statistical analysis..........................................................................................................................46 4.3.1.2a Analysis o f variance (ANOVA)..................................................................................... 46 4.3.2.2b Probit analysis................................................................................................................... 46 4.3.2 Identified Cyclops species........................................................................................................... 47 4.3.2.1 Tiokrom pond.................................................................................................................................47 4.3.2.2 Dzakpatra pond..............................................................................................................................47 4.3.2.3 Mataligu pond................................................................................................................................4 7 4.3.2.4 Kwesi Acheampong pond............................................................................................................ 47 4.4.1 Tables........................ ..................................................................................................................... 48 4.4.2 Figures............................................................................................................................................. .. 4.4.3 Plates............................................................................................................................................... .. vi 4? University of Ghana http://ugspace.ug.edu.gh CHAPTER 5. 5.0 DISCUSSIONS...........................................................................................................................102 5.1.0 FIELDW ORK...........................................................................................................................102 5.1.1 Pond Morphometry and Population Dynamics o f Cyclops...................................................102 5.1.2 Prevalence of Dracunculiasis in the study area.......................................................................105 5.2.0 LABORATORY W O RK ......................................................................................................... 107 5.2.1 Toxicity tests................................................................................................................................ 107 5.2.2 Identified Cyclops species.......................................................................................................... 110 CHAPTER 6. 6.0 CONCLUSIONS AND RECOM M ENDATIONS.............................................................112 (a) CONCLUSIONS.......................................................................................................... 112 (b) RECOM M ENDATIONS............................................................................................113 REFERENCES.......................................................................................................................................114 APPENDIX A. Q uestionnaire............................................................................................................. 124 APPENDIX B. ANOVA Results......................................................................................................... 126 APPENDIX C. Results of Probit analysis........................................................................................ 127 APPENDIX D. Key to Cyclops identification.................................................................................131 vii University of Ghana http://ugspace.ug.edu.gh Vlll A B S T R A C T Field studies were performed to identify the vector species o f Dracunculus medinensis. From these studies, Mesocyclops kieferi was implicated as a maj'or vector. Other vector species identified were Mesocyclops aspericornis and Thermocyclops inopinus. Studies were also carried out in the endemic villages using a questionnaire to ascertain the pattern of disease incidence during the years 1994- 1996. The results revealed that the socio-cultural practices o f the people assist in promoting the disease transmission. Of particular interest was noncompliance with control measures as well as traditional beliefs in the incidence and mode of transmission o f the disease. Toxicity studies were also undertaken in the laboratory to evaluate the effect of Temephos (ABATE) on different species of Cyclops (the vector of Dracunculiasis). Results obtained from these tests indicated 24-hr. LC50 values o f 0.58,1.59, 1.28 and 0.94ppm for Mesocyclops kieferi, Mesocyclops aspericornis, Thermocyclops inopinus and a mixture of species respectively. The corresponding LC95 values were 9.15, 6.98, 3.33 and 2.42ppm. Following a 48-hr. exposure, the concentrations of the insecticide required to effectively kill 50 and 95% of the Cyclops (mixture) were 0.34 and 0.84ppm respectively. An expired stock however produced 1.65ppm (LC50) and 5.36ppm (LC95) after a 48-hr. exposure. University of Ghana http://ugspace.ug.edu.gh ix LIST OF SYMBOLS AND ABBREVATIONS. (1) BMC Benzene hexachloride (2) CDRs Committees for the Defence o f the Revolution (3) DBL Danish Bilharziasis Laboratory (4) DDT Dichloro-diphenyl-tetrachloro-ethene (5) GW Guinea Worm (6) GWD Guinea Worm Disease (7) GWEP Guinea Worm Eradication Programme (8) GWEPS Guinea Worm Eradication Programmes (9) HE Health Education (10) IDWSSD International Drinking Water Supply and Sanitation Decade (11)L„L2,L3 Larval stages 1,2 and 3 respectively (12) LC Lethal Concentration (13) MOH Ministry of Health (14) NGO Non-Governmental Organization (15) Res. Resolution University of Ghana http://ugspace.ug.edu.gh TABLE 1-3: TOXICITY STUDIES........................................................................................................48 Table la: Showing the percentage mortality of each species (24-hr. Exposure)...................................48 Table 1 b: Showing the percentage mortality of each species (48-hr. Exposure)......................49 Table lc: Showing the percentage mortality o f Cyclops with age/state of Abate....................50 Table 2: Toxicity of Abate to different species of Cyclops................................................................... 51 Table 2a: Showing lethal concentrations (24-hr. Exposure)........................................................51 Table 2b: Showing lethal concentrations (48-hr. Exposure)........................................................52 Table 3: Comparative toxicity of fresh and expired Abate to Cyclops................................................53 Table 3a: Showing lethal concentrations (24-hr.).........................................................................53 Table 3b: Showing lethal concentrations (48-hr.).........................................................................54 Table 4: Seasonal variation in Cyclops density........................................................................................55 Table 5: Pond morphometry.......................................................................................................................56 Table 5a: Tiokrom pond.................................................................................................................. 56 Table 5b: Dzakpatra pond............................................................................................................... 57 Table 5c: Mataligu pond................................................................................................................. 58 Table 5d: Kwesi Acheampong pond.............................................................................................59 Table 6 : Lists of Cyclops identified from the different ponds................................................................ 60 Table 6 a: (Mepom) Kwesi Acheampong pond............................................................................60 Table 6 b: (Mepom) Mataligu pond................................................................................................61 Table 6 c: Tiokrom pond............................................................................................... 59 Table 6 d: Dzakpatra pond.................................................................................................... 53 X LIST OF TABLES University of Ghana http://ugspace.ug.edu.gh Table 7: Showing the distribution of Dracunculiasis in Tiokrom from 1994-1996............................. 64 Table 7a: Distribution by age and sex................................................................................ ............64 Table 7b: Distribution by occupation.............................................................................................65 Table 7c: Distribution by month.................................................................................................... 66 Table 7d: Site of worm emergence................................................................................................67 Table 8: Showing the distribution of Dracunculiasis in Dzakpatra from 1994-1996.......................... 68 Table 8a: Distribution by age and sex............................................................................................68 Table 8a: Distribution by occupation.............................................................................................69 Table 8a: Distribution by month.................................................................................................... 70 Table 8 a: Site of worm emergence................................................................................................. 71 Table 9: Showing the distribution of Dracunculiasis in Mepom from 1994-1996...............................72 Table 9a: Distribution by age and sex (Mataligu section)...........................................................72 Table 7a: Distribution by age and sex (Kwesi Acheampong section)....................................... 73 University of Ghana http://ugspace.ug.edu.gh are 1: Map of Guinea wonn survey/study area.................................................................................74 are 2: Generalised diagram of a Cyclops............................................................................................75 are 3: Toxicity o f Abate to Cyclops...................................................................................................76 Figure 3 a: Toxicity of Abate to Cyclops species (24-hr. Exposure)........................................ 76 Figure 3b: Toxicity of Abate to Cyclops species (48-hr. Exposure)......................................... 77 Figure 3c: Showing the percentage mortality of Cyclops with age/state o f Abate (24-hr. Exposure)............................................................................................................................ 78 Figure 3d: Showing the percentage mortality o f Cyclops with age/state o f Abate (48-hr. Exposure)............................................................................................................................79 ure 4: Seasonal variation in pond volume and Cyclops density..................................................... 80 Figure 4a: Tiokrom pond............................................................................................................. 80 Figure 4b: Dzakpatra pond........................................................................................................... 81 Figure 4c: Mataligu pond............................................................................................................ 82 Figure 4d: Kwesi Acheampng pond............................................................................................ 83 ,ure 5: Showing the distribution of Dracunculiasis in Tiokrom from 1994-1996.......................... 84 Figure 5a: Distrbution by age........................................................................................................84 Figure 5b: DistRibution by occupation........................................................................................ 85 Figure 5c: Distribution by month..................................................................................................86 Figure 5d: Site of worm emergence............................................................................................. 87 $ure 6: Showing the distribution of Dracunculiasis in Dzakpatra from 1994-1996......................... 88 Figure 6a: Distribution by age..................................................................................................... 88 Figure 6b: Distibution by occupation..........................................................................................89 Figure 6c: Distribution by month..................................................................................................90 Figure 6d: Site of worm emergence............................................................................................. 91 xii TJST OF FIGURES University of Ghana http://ugspace.ug.edu.gh LJSI OF PLATES. Plate 1: Female Guinea worm in two coils................................................................................................92 Plate 2-5: Physical characteristics of ponds with time/season.................................................................93 Plate 2 : Tiokrom pond................................................................................................................................ 93 Plate 2a: showing pond at maximum capacity............................................................................. 93 Plate 2b: showing pond at minimum capacity..............................................................................94 Plate 3: Mataligu pond................................................................................................................................95. Plate 3a: showing pond at maximum capacity............................................................................. 95 Plate 3b: showing pond at minimum capacity............................................................................. 96 Plate 4: Kwesi Acheampong pond............................................................................................................97 Plate 4a: showing pond at maximum capacity..............................................................................97 Plate 4b: showing pond at minimum capacity............................................................................. 98 Plate 5: Dzakpatra pond.............................................................................................................................. 99 Plate 5a: showing pond at maximum capacity............................................................................. 99 Plate 5b: showing pond with drastically reduced water level..................................................100 Plate 5c: showing pond completely dry......................................................................................101 University of Ghana http://ugspace.ug.edu.gh 1 Chapter 1 1.0 I N T R O D U C T I O N Guinea worm infection belongs to a group of maladies generally known as tropical diseases. These diseases which are caused by various parasites, are commonly associated with ignorance, poverty, malnutrition and squalor. As it is, parasitic diseases have been virtually eradicated from those countries in which the high socio-economic and educational standards of the people have engendered a proper appreciation o f the important role played by personal and environmental hygiene in the epidemiology o f communicable diseases. Further more, the provision of potable water, an increase in the level of awareness o f the people on the aetiology of the disease as well as the creation of conditions which inhibit breeding and development o f insects and other vectors of these diseases, lead to an improvement in the welfare o f the people (Ukoli, 1992). In contrast to the situation in the developed countries, life in tropical Africa, like in other parts of the Third World, is characterised by the terrible trinity o f poverty, ignorance and disease. Forgetting for the moment the debate on which came first in this vicious cycle, the net results is that they are interdependent. This cycle must be broken if any progress is. to be made in the socio­ economic development of the afflicted countries. Secondly, the health profile o f these nations is dominated by the most debilitating and disabling o f parasitic diseases such as malaria, schistosomiasis, trypanosomiasis, leishmaniasis and tilariasis (including onchocerciasis and Dracunculiasis). Although these parasitic diseases form one of the obstacles to the development of the Third World, national budgets are unfortunately often too meagre for preventing or controlling them effectively. The major preoccupation o f the people, and this is a more realistic University of Ghana http://ugspace.ug.edu.gh view, is to secure enough food, reasonable environmental quality and develop societies in which humane values prevail (Kale, 1990; Ukoli, 1992). Apart from the internationally quarantinable diseases (cholera, plague, and yellow fever) which from time to time occur as pandemics, there are those which are confined to special risk groups within defined national boundaries. Diseases in this group include measles, meningitis and paralytic poliomyelitis. The third group is made up of the "invisible'’ and neglected epidemic diseases. Invisible and neglected because, although they are often fatal, they tend to occur in and be confined to remote agrarian communities. These residents, although constituting approximately 75-80% of the population in Africa, have little or no access to even the most basic modem health facilities (Kale, 1990; Rab et al., 1991). Moreover, these communities do not possess the sort o f political, economic or social clout that could compel urban-based decision makers and providers of medical care to undertake meaningful and effective interventions aimed at eliminating or controlling these diseases. A classical example of a disease that belongs to this group is Dracunculiasis or Guinea worm infection (Kale, 1990). This filarial infection has until recently been neglected in national control programmes because there is no effective treatment currently available and affected villagers rarely seek medical care. However, the fact that Dracunculiasis causes severe disability, with major consequences for public health, education and agriculture have been highlighted (Smith et al., 1989; Brieger and Guyer, 1990; Kambire et a l , 1993). Despite its low case-fatality, Guinea worm Disease does cause severe disability, often for protracted periods of time and at critical times of the agricultural season (Belcher et a l , 1975; Kale, 1977; Nwosu et al, 1982). While the annual prevalence rates vary widely from one area 2 University of Ghana http://ugspace.ug.edu.gh another, some villages report an annual prevalence rate of up to 70%, with the disease primarily affecting the most productive members o f the village (Belcher el a l , 1975; Kale, 1975; Nwosu et a l, 1982; Hopkins, 1983; Edungbola and Watts, 1985). A true case of Guinea worm is recognised as a long, white thread-like worm coming out from an ulcer or sore on the skin of the affected person (Brieger and Rosenwieg, 1988; Rab, et al., 1991). The mature worm makes a partial exit to discharge its larvae into water in the process of procreation. Ebenhard et al., (1989), however reported two unusual cases o f Dracunculus medinensis. Both involved the emergence of a bright red worm, typical in size and location to D. medinensis. "To our knowledge, these cases are the first reported in modem literature o f the emergence of red worms through the skin o f humans", they concluded. Clinical features o f Guinea worm at the time of blister formation (the first sign of infection), include local itching, urticaria and a burning sensation at the site o f a small blister (Muller, 1971). Dracunculiasis, although posing a serious health problem in Africa, Asia and the Middle East where people rely on ponds or wells for their drinking water, remained as an ignored problem for many years. There is now, however, a greater realization o f the public health importance of the disease, especially the burden it posses on human health and welfare, and in particular on agricultural productivity. There is therefore heightened interest in the eradication of the disease in Ghana as a means o f removing a serious obstacle to socio-economic development, especially in the rural areas. It is however important to note that the Guinea Worm Eradication Programme (GWEP) in the country has a checkered history, with documented dates of commencement ranging from 1987 to 1989. The Plan of Action of the GWEP in Ghana states the methodology, strategy, 3 University of Ghana http://ugspace.ug.edu.gh targets and the estimated cost of achieving the objective of total eradication of the disease by the year 1995 (this date has since been extended twice; the current target date being 6 th March 1997). The programme in Ghana began identifying and training resident village volunteers (VVs) to report cases of dracunculiasis in endemic communities in the early part o f 1989 (Hopkins et a l , 1991). Control measures were directed towards freeing domestic water sources of Cyclops and preventing infected people from contaminating water supplies. These measures included boiling, filtering and chemical treatment of unsafe drinking water (Quashie, 1982). The GWEP in Ghana is supported by the government as well as donor agencies such as the Carter Centre in Atlanta Georgia, the then Bank for Credit and Commerce International (BCCI) and the Sasalcawa Global 2,000 Project. Since the government recognized the need to eradicate Dracunculiasis as a means of poverty reduction, the National Guinea Worm Eradication Programme was incorporated into the Ministry o f Health (MOH) with an autonomous administration headed by a National GWEP Coordinator. The mandate o f the programme was to evolve a focal control strategy for eradicating the disease by 31st. December, 1995. The intervention strategies adopted were based on seven points: (i) Surveillance. (ii) Health Education (HE). (iii) Provision of safe drinking water. (iv) Training. (v) Monitoring and evaluation. (vi) Research. (vii) Vector control. 4 University of Ghana http://ugspace.ug.edu.gh 5 The main emphasis of the GWEP as of July 1995 was all but research. An extraordinary level of public mobilization was achieved in June 1988 when the Head of State, Fit. Lt. Jerry John Rawlings spent eight days visiting 21 villages in which the disease is endemic in the Northern Region, promoting the goals of the national eradication campaign: "an exceptional degree of involvement by any head of state in combatting any disease" (Report on IDWSSD Impact on Dracunculiasis, October 20, 1989). Ghana also began distributing several copies o f a manual to Secondary Schools in 1989 for teaching on the Guinea worm disease. Both Ghana and Nigeria are placing great emphasis on Health Education, Community Mobilization and Rural Water Supply in their control programmes. An extensive use o f Temephos (ABATE) in selected villages began in these countries in 1991 (Report on IDWSSD Impact on Dracunculiasis, October 20, 1989). University of Ghana http://ugspace.ug.edu.gh Chapter 2 2.0 LITERATURE REVIEW. 2.1.0 HISTORY OF DRACUNCULUS MEDINENSIS. Guinea worm disease (Dracunculiasis, Dracontiasis, or Dracunculosis), is one o f the ancient scourges of mankind. It is believed to be the "Fiery Serpents" referred to by Moses in the Old Testament (Numbers, 21:6) when it plagued the inhabitants settled along the shores o f the Red Sea at that time (Rab, 1989; Muller, 1971). This fact is further buttressed by the many vernacular names used to describe the parasite (Guinea worm, Medina worm, filaire de Medine, le dragonneau, pharaonswurm (Muller, 1971;Ukoli, 1992). The first documented information on Dracunculus medinensis (Linnaeus, 1758) was found in the writings o f Egyptian, Roman and Greek physicians (Litvinov and Lysenko, 1982). Al Rhazes (865-920) showed for the time that swelling caused in the disease is due to a parasite, the Guinea worm. Avicenna (980-1037) was the first to give a detailed clinical description o f an illness that was called Madina sickness which was common in that region. Historically, there has however been a lot of debate concerning the origin o f the disease. Yelifari (1993) reported that Manson-Bahr (1966), believed it was imported from America, while Abren described it as an African disease (Guerra, 1968). Likewise, there seems to be considerable confusion concerning the nature of the disease. Thus, while Aetius Paulus and Rhazes felt it was a worm, others such as Seramus and Pollux called it a corrupt nervous substance. Still other schools of thought had different interpretations. Garraeus, Aldrovni and, Montramus felt it was a tumour, an abscess, an elongated vein, a black bile, a fibrous concentration or an atrophied cellular tissue. 6 University of Ghana http://ugspace.ug.edu.gh tissue. Undoubtedly, Amatus Lusitanius (1551- 1568), was aware of the animal origin o f Guinea worm as he wrote; "authors are in doubt whether this is a nerve, a vein or a worm. But I have seen the condition with my own eyes and bear witness that a thin white worm in many coils was found" (Grove, 1990; as cited in Yelifari, 1993). In 1674, Velschius wrote about how Dracunculus medinensis was put on ancient Roman emblems, in Arabic lettering, in many Greek sculptures and in the emblem o f the medical profession and still described it as verminous. According to Yelifari (1993), Avicinus, following Galen, thought that the disease was o f nervous origin until he noted the animal origin o f the pathogen. Also, Monographs by Velschius (1674) and Barlet (1909) give lists o f historical references (Muller, 1972). Interest in the structure o f the parasite dates from the seventeenth and eighteenth Centuries. In 1674, Velschius described the parasite and discussed various theories concerning its existence. In 1758, Linnaeus published his Systerna Naturae, in which names were given to all the then known helminths, including the dracunculus parasite, which therefore bore the name Dracunculus medinensis. In 1868, a young Russian researcher called Alexksi Pavloviv Fedchenko (1844-1873) noted the great harm caused by Dracunculus medinensis to the health o f the populations o f Samarkhand, Bukhara, Dzizak and Karshi. Consequently he begun to study the disease in 1869. Until the middle of the nineteeth Century, there were four points of view as to how humans contracted the disease. Thus, the parasite larvae either: (i) were carried by insects, (ii) were dispersed in the air and entered the human body when infected air was breathed, (iii)entered the human body with food and water or (iv) were present in ponds and soil and entered the human body through uncovered parts. 7 University of Ghana http://ugspace.ug.edu.gh In 1869, Fedchenko discovered Dracunculus medinensis larvae in the body cavity of a copepod {Cyclops). He also successfully infected Cyclops with larval parasites in a number of experiments and traced their development in the Cyclops. Fedchenko’s discovery of the intermediate host of dracunculiasis provided information on the life-cycle of the helminth and explained how the disease is contracted. This was one of the mile-stones in the history of tropical medicine, as it was the first record of an arthropod acting as an intermediate host in the transmission of a human disease, some years before Manson's more famous implication of Culex mosquitoes in the transmission of bancroftian filariasis. Based on this discovery, Fedchenko put forward the epidemiological formula of Dracunculiasis: Cyclops are the intermediate hosts; Cyclops are infected with larval parasites that enter water from a person with the disease; and man becomes infected when he drinks unwholesome water containing Cyclops with mature larvae in their bodies (Litvinov, 1982). 2.2.0 TAXONOMY AND LIFE-CYCLE OF DRACUNCULUS M E D IN E N SIS . 2.2.1 Taxonomy The phylogenetic systematics of Dracunculus medinensis has seen some form of metamorphosis as has been the case for most organisms. In literature therefore, the Nematoda is sometimes listed as a class within another phylum, the Aschelminthes. The Aschelminthes are often referred to as the "Cavity worms” because they posses a pseudocoel. The majority o f groups contained within the Aschelminthes (Nematoda, Rotifera, Gastrotricha, Kinorhyncha, Nematomorpha, Acanthocephala and Gnathostomulida) are now generally considered more distantly related, so that each class has been elevated to the phylum status (Pechenik, 1991). Thus, Dracunculus medinensis has been assigned the following taxonomic groups. University of Ghana http://ugspace.ug.edu.gh 9 PHYLUM: Nematoda CLASS: Secernentea. SUBCLASS: Spiruria. ORDER: Camallanida. FAMILY: Dracunculidae. GENUS: Dracunculus. SPECIES: medinensis. SCIENTIFIC NAME: Dracunculus medinensis. COMMON NAME: Guinea worm. 2.2.2.0 LIFE-CYCLE OF DRACUNCULUS M EDINENSIS . 2.2.2.1 Discovery. Although the discovery of the Life-Cycle of Dracunculus medinensis has usually been credited to Fedchenko (1869), Manson-Bahr (1966) made the following statement: "Fedchenko (1869) is credited with the discovery of the transmission o f the guinea worm, but probably, Manson was the original observer (1895). He believes that the stages figured by the former are those of Cucullanus spp (a parasite of fish), and not D. medinensis" (Hughes, 1967). Hughes however agrees that Fedchenko correctly postulated that human infection is caused by the ingestion o f infected Cyclops in drinking water. This was obviously because he was already aware that the life-cycle of some parasitic helminths involved alternative hosts, and he was looking out for such a host for the Guinea worm. University of Ghana http://ugspace.ug.edu.gh Conversely, an investigator 75 years earlier did not know about alternative hosts, and so he (Manson) missed the complete story as unfolded by Fedchenko. Colin Chisholm (1795) also noted the occurrence o f the "dracunculus or Guinea worm” and wrote: "The cause o f this singular disease seems to be confined to the water of some wells". He described how filling up these wells prevented the spread of the disease, and continued; "In the water which contains the embryos o f the dracunculi, the naked eye distinguishes innumerable animalculi, darting in every direction with astonishing force and rapidity; these on being subjected to examination with a small microscope, exhibit a very extraordinary figure, differing from any animalcule hitherto described" These were surely Cyclops. Thus, it was Fedchenko's better knowledge o f parasitology and familiarity with the appearance o f unparasitised Cyclops which enabled him to make the observations that had eluded Chisholm; that the Guinea worm embryos were inside Cyclops (Hughes, 1967). Another account of the mode of transmission of Guinea worm is given by Sir James Emerson Tennent. As the Colonial Secretary of the British Government in Ceylon from 1845 to 1850, Tennent noted in the course of a description of "parasitic worms" found there, that "of these entozoa, the Filaria Medinensis or Guinea worm which burrows in the cellular tissue under the skin, is well blown in the north of the Island, but rarely found in the damper districts of the south and west. The natives of these areas attribute the occurrence to drinking the waters o f particular wells" Tennent thus records the fact that the mode of infection/transmission seems to have been known on the African coast in at least the sixteenth century, and in Ceylon for some time before the establishment of British rule in the eighteeth century, thereby giving additional support to Dr. Muller's contention that "the belief that transmission is associated with wells and water holes has been held since ancient times". Tennent also goes further to suggest that "these pests in all probability received their popular name of Guinea worm from the narrative of Bruno or Braun, a citizen or surgeon o f Balse, who 10 University of Ghana http://ugspace.ug.edu.gh about the year 1611 made several voyages to that part of the African Coast, and on his return, published, among other things, an account of the local diseases'* (Goonertne, 1969). 2 2 2 2 Life-Cycle. The rather bizarre Life-Cycle of the Guinea worm, Dracunculus medinensis, is actually very well adapted for the transmission of a parasite that utilises an aquatic intermediate host which occurs principally in arid or semi-arid environments. The mature female worm is about 70-100cm long and 0.20cm wide (Plate 1) and lives in the subcutaneous connective tissue o f the human host. Human infection occurs when Cyclops containing the infective stage larvae (L3) in water are ingested. The Cyclops are killed by gastric juices in the stomach and the larvae are activated and liberated and quickly pass through into the duodenum o f the human host within 4 hours after ingestion (Muller, 1982). In experimentally infected animals, the larvae are seen to penetrate through the duodenal wall in 10 to 13 hours post ingestion, and migrate via the mesenteries to the abdominal and thoracic muscles by about the fifteenth day (Rab, 1989). The larvae do not grow during this period , but there is probably a moult between the fifteenth and the twenty-first days. As they develop further, they begin to migrate towards the connective tissues of the axillary and the inguinal regions where they mature into adult worms. The size of the worms at this stage remains small and mating occurs between 80 and 100 days after infection (Muller, 1982). The males, (size: 1 to 4cm long) move into the deeper tissues and perish after six months. Within eight months after infection, the gravid female is filled up with developing eggs and with first-stage larvae by the tenth month. At this time, the worm begins its migration usually towards the extremities and is ready to emerge from the body 11 University of Ghana http://ugspace.ug.edu.gh between 10 to 14 months after infection. Before, the 14th month, the gut becomes flattened and non­ functional, and the whole worm is filled by the larvae-containing uterus (Muller, 1982). When the worm (female) is ready to emerge, the anterior end o f the worm provokes the formation of a painful burning blister in the human skin. The worm emerges when this blister ruptures (especially upon coming into contact with water). Numerous first stage larvae (L,) are expelled into the water in a milky white stream. Estimates of the number of larvae contained in the uterus of a single worm range from 1.4 to 3.0 million. Not all the larvae are released at once, and it has been shown that about half a million larvae are released on first immersion in water. The anterior end of the worm then becomes flaccid and dries up. When the affected part comes into contact with water again more larvae are expelled through the broken end o f the worm. The number o f larvae expelled at each immersion decreases, and the worm is completely expelled within one to two weeks. This intermittent discharge and drying up o f the blister aperture is an adaptation to increase the chances of some of the larvae finding Cyclops in the water. This process is “one o f the neatest adaptation in behaviour in all of the realm of biology, enabling a blind unmediative burrowing worm to give her aquatic Cyclops-inhabiting offspring a fair chance in life, even in deserts” (Rab, 1989; Muller, 1971). The first stage larvae, (640 by 13fx) remain active in the pond for about one W'eek. Following ingestion by a Cyclops, the larvae penetrate the gut wall o f the Cyclops and reach its haemocoel within one to six hours. They moult twice inside the Cyclops and reach the infective third larval stage (L3) in 14 days. It is when man drinks this Cyc/op^-contaminated water that the cycle is repeated (Rab, 1989; Muller, 1971; Brieger and Rosenweig, 1988). 12 University of Ghana http://ugspace.ug.edu.gh The rate of development o f the larvae in the Cyclops has been found to be temperature dependent. Temperatures above 24 °C and below 19 °C inhibit the growth o f the larvae, which are then incapable of reaching the infective stage. It has also been observed that those larvae-containing Cyclops are sluggish in their movements and tend to sink to the bottom of the ponds, as compared to the non-infected ones. There is also some evidence to suggest that the life span o f the infected Cyclops is shortened (Rab, 1989). The following is an annotated diagram o f the Life-Cycle o f Dracunculus medinensis. 13 University of Ghana http://ugspace.ug.edu.gh LIFE-CYCLE OE DRACUNCULUS M EDINENSIS, (GUINEA WORM: CAUSES. PREVENTION AND “TREATM ENT S 14 Prevention: a) improve water supply (wells etc.) b) filter or boil drinking water c) kill Cyclops (A bate/Tenephos) Treatment: a) medication (niridazole, aspirin, etc. } b) prevent secondary infection (tetanus immunization, clean 1 J 1nfected Person Wades >n Pond: Guineaworm Expel Larvae T Prevention: t) protect pond b) kill cyclops Source: Brieger and Rosenweig, 1988. University of Ghana http://ugspace.ug.edu.gh 2.3.0 TAXONOMY, BIOLOGY AND ECOLOGY OF CYCLOPS: The vectors of guineaworm are cyclopoid copepods that inhabit stagnant ponds (Figure 1). Dracunculus medinensis however exhibits a high level of host specificity and only a few species act as vectors in nature. Cyclopoid copepods (Cyclopoida) are known as the intermediate hosts o f more than ten genera of the Cestoda and Nematoda. Two among these are important parasites o f man; Diphyllobothrium latum (the broad fish tapeworm) and Dracunculus medinensis. Mesocyclops leukarti (Claus) is widely reported as the common intermediate host in India (Sarkar, 1982) and Africa (Onabamiro, 1950; Muller, 1970). Other reported hosts include species of the genera Mesocyclops Sars (Sarkar, 1982), Thermocyclops Kiefer (Onabamiro, 1952a) and Metacyclops Kiefer (Steib, 1985). The correct identification of the copepod intermediate hosts is therefore not only important in mapping out the geographical distribution and spread o f the disease, but also vital in the development of eradication programmes which aim to combat the disease by vector control (Boxshall and Braide, 1991). Copepods (classified as Macrozooplankton, Sensu striclo) are subdivided into Calanoids, Cyclopoids and Harpacticoids. Recent progress in copepod systematics has refined the level of taxonomic resolution of these freshwater copepods and it is now known that Mesocyclops leukarti does not occur in either Africa or India (Keifer, 1981; Van de Velde. 1984). There is, therefore, an obvious need to record these taxonomic changes, to review earlier records, and to update the nomenclature of the hosts where possible (Boxshall and Braide, 1991). The various groups have been observed to have diverse feeding regimes, often modified in the course of development. Cyclopoids have an erratic jumping motion which makes them more conspicuous than the gliding motion of calanoids (Delince, 1992). 15 University of Ghana http://ugspace.ug.edu.gh The broad taxonomic grouping of Cyclops is as follows; Phylum: Arthropoda Subphylum: Crustacea Class: Copepoda Order: Cyclopoida Family: Cyclopidae Thus, Cyclops belong to the Cyclopoid copepods, one of the orders in the class Copepoda. The Copepoda is included in the subphylum Crustacea which also include such familiar invertebrates as crabs, shrimps and lobsters (Barnes, 1968). Freshwater Cyclopoid copepods are minute, pinhead­ sized crustaceans which are biologically very successful, comprising many genera with diverse feeding habits. They are found world wide and almost exclusively in standing or slow-flowing, marine, brackish and freshwater bodies. The free living cyclopoid copepods (often referred to as Cyclops), have pear-shaped bodies, comprising a cephalothorax, an abdomen and a telson with a tail which has two caudal rami. The sexes are separate and the eggs hatch into typical nauplius larvae, which are then succeeded by several metanauplius stages before moulting into the first o f five successive copepodite stages (McCullough, 1982). Muller (1971), listed 17 species o f Cyclops that potentially act as intermediate hosts in different dracunculiasis endemic areas. More recently Steib, (as cited in Olsen, 1993), working in Burkina Faso, added two more species (Thermocyclops incisus and Metacyclops exsulis) to the list of potential vectors. In Africa however, approximately 150 different species o f freshwater cyclopoids have been described. O f these only 60 are prevalent in areas endemic for Guinea worm disease. Probably, only 34 o f these species are frequent vectors. Generally, only members o f the genera 16 University of Ghana http://ugspace.ug.edu.gh Thermocyclops and Mesocyclops are regarded as truly planktonic forms and can therefore act as the most important vectors of the disease (Kiefer, 1978; as cited in Oslen, 1993). McCullough (1982), states that only large predatory species can readily ingest Dracunculus medinensis larvae and can therefore act as potential intermediate hosts. O f these carnivorous species, the older and larger copepodid stages are more predatory than the younger smaller ones. Also, that in each endemic zone usually one of the local predator species is the dominant intermediate host by virtue of its preferred habitat and seasonal population dynamics or both. Furthermore, Boxshall et a l, (1991), working on the freshwater Cyclopoid copepods o f Nigeria, identified forty valid and four non-valid vector species o f dracunculiasis. Species in the genera Thermocyclops, Mesocyclops and Melacyclops are often implicated as intermediate hosts of D. medinensis. Boxshall and his coworkers were however quick to warn that the often implicated (and misidentified) host, Mesocyclops leukarti does not occur in either Africa or India. This view is also held by Olsen (1993), who states in his key "Vectors o f Guinea worm disease in tropical Africa - A key to the species of Thermocyclops and Mesocyclops", that of the 13 taxa o f this genus described for Africa, most forms were recorded as Mesocyclops leukarti, which does not in fact occur in tropical Africa. Chippaux (1991), also identified 14 species o f cyclopoids out of which 4 were suitable intermediate hosts for D. medinensis. Of these, Thermocyclops oblongatus appeared to be the most common, especially in ponds, followed by T. neglectus whilst T.crassus consimilis was considered a minor intermediate host. T. emini also played an important role as an intermediate host, especially in rivers at the beginning of the dry season when the rivers had stopped flowing (Chippaux, 1991). Other species of Cyclops known to transmit Dracunculus medinensis are Thermocyclops nigerianus and T. hyalinus (Onabamiro, 1950). 17 University of Ghana http://ugspace.ug.edu.gh With respect to the food and feeding habits o f Cyclops, the work o f Klugh (1927), gives a comprehensive review of the food of freshwater Entomostraca (Birge, 1897; as cited in Fryer, 1955). Klugh also recorded the alga Chaetophora elegans, Chlamydomonas as well as Diaptomus birgei from various genera o f Cyclops. He also claimed that Cyclops are carnivorous, eating rotifers, nauplii and ''other animals" Horse dung infusions (essentially protozoan cultures) appear to have been the chief source of food used in cultures. Coker (1933; as cited in Fryer, 1955), remarks that this medium is satisfactory for the rearing of Acanthocyclops vernalis and Eucyclops (= serrulatus), but states, "we had reason to doubt its effectiveness with respect to the fertility of adults reared as to its general sustainability for A. v i r i d i s Later Coker noted that he had satisfactory results by the addition of unicellular green algae and chopped fragments of the filamentous green alga Mougeutia spp. to the culture medium (Fryer, 1955). Fryer also revealed that individual species of Cyclops had preferred food material. The carnivorous species included Macrocyclops albdus, M. fuscus, Acanthocyclops viridis, A. vervalis, Cyclops strenuus and Mesocyclops leukarli. The herbivorous species were mostly from the genus Eucyclops and some Microcyclops. The physico-chemical properties of Cyclops habitats depend on the general pattern of seasonal events. As Burgis (1971), points out, in the temperate lakes, the seasonal changes are due mainly to the incident solar radiation, and the consequent changes in water temperature leads to an alternate building-up and breakdown of thermal stratification. In the tropical regions however, incident solar energy is high throughout the year, thus, diurnal stratification is of greater significance than seasonal changes. This phenomenon is pronounced in large bodies o f water. In the small ponds that are often used as sources of drinking water, the almost constant mixing o f the water produces an environment remarkably homogenous, with stable physico-chemical conditions. The only apparent seasonal changes are those associated with increased inflow during the rainy season and the consequent increase in volume/level, probably coupled with increased turbidity (Fryer, 1955). 18 University of Ghana http://ugspace.ug.edu.gh 19 2.4.0 EPIDEM IOLOGY AND IM PORTANCE OF GUINEA W ORM DISEASE. 2.4.1 EPIDEM IOLOGY. Once rampant in most of the Middle East, Africa as well as Central and South Asia, Dracunculiasis is now restricted to only 19 countries of the world; 17 countries in Africa, as well as India and Pakistan. It was introduced into several Latin American countries and the Caribbean Islands along with the "Slave Trade", but apparently all the new World foci are now extinct (Rab, 1989). In a personal communication, Rab (1995), claims the disease has now been eradicated in Pakistan. The disease is most severe in the West African countries of Benin, Burkina Faso, Ghana, Mali, Mauritania, Niger, Nigeria, Senegal and Togo. Serious disease problems also exist in areas of East Africa such as Ethiopia, Sudan and Uganda. In India, the disease has been eradicated from the Southern region of Tamil Nadu, however, it still affects many districts in the two Northwestern states of Andhra Pradesh and Rajasthan which shares borders with Pakistan. There are controversies as to the estimated number of people who suffer from this debilitating disease per year in the endemic regions. Whilst Edungbola el a l (1988) puts it at 5-15 million, Rab et a l , (1991) gives a range of 10-48 million. The WHO (1993) also estimates the annual incidence to be o f the order o f 50 million people. Of the 17 countries in Africa that are hard hit by the disease, 9 are in West Africa. Nigeria, the most populous country in Africa (101 Million), undoubtedly tops the list whilst Uganda comes second. In Niger the population estimated to be at risk is pegged at 2.5M (Edungbola et a l , 1988). If the absolute number of cases in the West African countries in 1990 are to be compared, Burkina University of Ghana http://ugspace.ug.edu.gh Faso comes third after Nigeria (194,082 cases) and Ghana (123, 793 cases). However, if prevalence per 10,000 population is compared, Ghana ranks highest (82.5 per 10,000), followed by Benin (81.3) and Burkina Faso (46.4) (Kimbire et a l , 1993). Dracunculiasis is equally devastating in the Sudan where the government has embarked on a nationwide campaign involving the use o f radio, television and the Newspapers to eradicate the scourge. The disease has spread to 21 o f the 26 states of this North-Eastern African country where it is estimated that some 50,000 people have died o f Guinea worm-related diseases. The situation is further compounded by the civil war in that part of the country, leading to a total collapse in medical services (The African Obsrver, April 3-15, 1995). 2.4.2 The Socio-economic Im portance. Dracunculiasis is endemic in much of the Guinea Coast of West Africa (Muller, 1971., Nwosu et al, 1982 and Belcher et a l , 1975). The disease does not confer protective immunity and hence, reinfection of the same individual year after year is not uncommon. Secondary bacterial infection of Guinea worm (GW) ulcers occurs in about 50% o f cases, and many farmers are too incapacitated to work for up to three months, some for longer periods, and still others are permanently disabled (Kale, 1991). The disease therefore causes considerable suffering and poses a major problem to the health and economy of the rural population in the endemic areas. A few examples will suffice to illustrate the impact of GWD. on the socio-economic status o f affected communities. In Togo, with a national population o f2,747,000, the estimated number o f lost workdays per annum is put at 40 million. In Nigeria, with a population of about 100 million, about 120 million workdays are lost, 50% of them to agriculture alone. The World Bank estimates the value o f the 20 University of Ghana http://ugspace.ug.edu.gh global loss of marketable goods attributable to Guinea worm at $1 billion. In Burkina Faso, as much as 10% of per capita income may be lost because of guineaworm disease. Between $56 million and $277 million in wages are lost globally every year as a result of Guinea worm infection . A UNICEF- sponsored study in a part of Nigeria with a population of 1.6 Million suggests that the annual losses in rice production profits alone is of the order of $20 million. If these losses are extrapolated to the rest of the areas of the country susceptible to Guinea worm infestation, taking into account other crops, the total annual agricultural loss caused by Guinea worm in Nigeria, where about 2 million cases occur in all the States of the Federation, is of the order of three-quaters o f a billion dollars (Kale, 1990). 2.4.3 Endemicity of Guinea W orm Disease in Ghana. Although Belcher (1975) and his co-workers reported that little was known about the extent of Guinea worm disease in Ghana, they also indicated that the disease has previously been reported in the northern and middle sections of the country. Scott (1959), also reported that investigations were carried out into Guinea worm infection in the Mo district of north-west Ashanti between 1952 and 1958. Scott further stated that the disease is particularly common in this area which lies to the north-west of Kintampo. The area has a typical woodland savannah vegetation, and covers about 250 square miles. There are 27 villages and hamlets, and the incidence o f dracontiasis was as high as 40% in some of the villages (Scott, 1959). In Ghana, as pertains in the other West African countries, Guinea worm infection is restricted to the rural poor who lack potable/treated water. Out o f the ten regions, eight are declared as Dracunculiasis endemic. These are; The Upper East and West Regions, Brong-Ahafo, Ashanti, 21 University of Ghana http://ugspace.ug.edu.gh Greater Accra, Eastern, Central and The Northern Region which has the highest annual prevalence. According to the Ministry of Health Annual Report (Greater Accra Region), the number of reported cases of Guinea Worm disease in the country for 1993 was 17, 918; a reduction by 46.5% o f the 1992 figure. Also the number o f villages in which the disease was endemic reduced by 28.4% during the same period. The main strategies that accounted for the reduction in prevalence included: (i) Intensification o f Health Education, (ii) Vector control through the application of ABATE 500EC to the sources of drinking water, (iii) Worm Extraction by surgical means, and (iv) Community based surveillance. As at the launching of the Guinea Worm Eradication Programme in 1989, there were no reliable estimates of the prevalence of the disease in the whole country, with the hospital records showing gross under-reporting. The number of cases reported annually throughout the country from 1982 to 1986 ranged from 3,413 to 4,717. However, a survey conducted in 1987 in Northern Region revealed an 8% infection rate, with 80% o f the villages being endemic. It was also estimated that at least 90,000 GW cases occurred in that region. In contrast, a sample survey in the Eastern Region in February 1988 yielded a regional prevalence rate o f 11%. 2.5.0 CONTROL AND PREVENTION OF GUINEA W ORM DISEASE. Although Dracunculiasis appears to be a very simple disease to eradicate, mankind is still plagued by this ancient malady in the dying embers of the twentieth century. The disease has therefore eluded man for ages. The failure to eradicate guinea worm could be due to a number of factors. 22 University of Ghana http://ugspace.ug.edu.gh Apart from being a disease of the rural poor, it is also impossible to diagnose until the formation of a blister approximately a year after infection. This is the one and basic factor underlying the failure of chemotherapy for the control of Dracunculiasis. In fact, no known drug exist for treatment, and there is no vaccine available. Thus, the only options left for control that appear feasible are; Vector control, Health Education and more importantly the Provision of potable drinking water to all endemic communities. McCullough (1982), enumerated a number of factors that are implicated for the long neglect of studies on Dracunculiasis. These are that; (a) Globally, the distribution and public health importance o f the disease does not compare with such other parasitic infectious diseases as malaria, schistosomiasis and soil transmitted helminths, thus its priority is relatively low. (b) Nationally, the disease is seasonally restricted to small, often isolated communities located in impoverished areas without, to say the least, political influence and with little chance of benefit from concerted public health activities. (c) There are no effective drugs nor vaccines for the treatment or prevention of the disease. Infected villagers therefore have little incentive to seek treatment at hospitals or dispensaries, and tend to rely much more on traditional methods. Consequently, the true gravity of the malady is often hidden. (d) Prevention and control of Dracunculiasis demand a multi-disciplinary approach. (e) Biologists have for obvious reasons, concentrated chiefly on medical entomology, occasionally on malacology, and hardly ever on the subclass Copepoda, probably because so few important human parasites are transmitted by this latter group. Of late however, non-governmental organizations such as UNICEF, WASH, World Vision International and the Global 2000 Project o f the Carter Foundation, Georgia-USA, have 23 University of Ghana http://ugspace.ug.edu.gh succeeded in bringing the misery and havoc caused by this incapacitating disease into the limelight. Thus, GWEPS were initiated by most endemic countries in the late 1980s. These programmes are multi-disciplinary, multifaceted and integrated in approach. They are not only included in the existing health delivery systems, but also inter-sectorial collaboration within and between the various arms of health services is emphasised. Among other things, health education, chemical treatment of contaminated water sources and to a lesser extent, chemotherapy and surgical removal of worms as well as the provision of safe drinking water are carried out. 2.5.1 Health Education. Even though health education has proven to be an effective tool in combatting Dracunculiasis, some degree of community mobilization, commitment and cooperation, involving both infected and non-infected members are required. These measures essentially include boiling or filtering of drinking water and the prevention o f infected individuals from entering sources of drinking water. Of these measures, filtration is the more attractive option since it is the easier of the two methods. Conversely, boiling will mean the use of firewood, and this is not only expensive, but also promotes deforestation and consequently global warming. A 100|j.m monofilament filter has been shown to effectively remove Cyclops from drinking water and resist clogging as well. This is being used extensively in villages where the disease is endemic in Pakistan, where it is readily accepted and lasts at least one transmission season if handled with care. Meticulous and thoroughly planned health education programmes in certain communities have brought about significant changes in health behaviour, and has 'esulted in drastic reductions in the prevalence of Dracunculiasis within two years in such communities (Akpovi et al., 1981). 24 University of Ghana http://ugspace.ug.edu.gh In Ghana, Health Education (HE) is done by the GWEP mainly by the programme coordinators and the village volunteers (VVs). These VVs are usually selected by the indigenes themselves and are therefore more acceptable and effective. Also, opinion leaders such as Assemblymen, chiefs, CDRs as well as identifiable groups are involved in this exercise. This has led to drastic reductions in the prevalence of the disease in most villages where the disease has been hitherto highly endemic. 2.5.2 Provision of Safe Drinking Water: Since ingestion o f contaminated drinking water is the only mode o f transmitting Dracunculiasis, the provision and use of drinking water that is not contaminated with the Cyclops interrupts transmission and results in the disappearance of the disease in one to two years. In the Ivory Coast, a well drilling programme in the 1970s reduced the prevalence o f Dracunculiasis from 30 to 1%, whilst a town in Nigeria recorded a decrease from 60 to 0% in 2 years. Likewise in Pakistan, provision of pipe water by the Public Health Engineering Department has eliminated the disease from some previously known infected foci o f high endemicity (Rab, 1989). It must however be emphasized here that, the provision o f safe drinking water to infected communities alone does not always result in disease eradication. The proper use o f such water must be simultaneously ensured. Several instances are recorded in which villagers continue to use traditionally contaminated sources despite having safe water supplies. 2.5.3 Treatment: Ancient as Dracunculiasis is, there is up to date no known cure for the disease. Thus, in the endemic communities, there are numerous traditional remedies employed for treatment. The most common and popular among these is the time old method of winding the worm on a forked i stick as it emerges. This method has been in use in Africa and Ceylon as far back as the sixteentii 25 University of Ghana http://ugspace.ug.edu.gh century or even earlier. The Dutch navigator, Linschoten, saw evidence of Guinea worm at Ormusz in 1584, and consequently described the worms as well as the local method of removal as follows: "There is in Ormus a sickness or common plague of wormes, which growe in their legges, it is thought that they precede of the water they drink. These wormes are like unto lute strings, and about two or three fathomes longe, which they must plucke out and winde them aboute a straw or feather, everie day some part thereof, so longe as they feele them creepe; and when they hold still, letting it rest in that sort till the next daye, they bind it fast and amongst the hole, and the swelling from whence it commeth forth, with fresh butter, and so in ten to twelth dayes, they winde them without any let, in the meanetime they must sit still with their legges, for if it braek, they should not without great paine get it out o f their legges, as I have seen some men doe" (Gooneratne, 1926). (i) Chemotherapy; The fact that so many traditional methods o f "treating" Guinea worm are still in use today reflects the lack of a modern chemotherapeutic agent. "Treatment" efforts are therefore aimed at removal of the emerging worms, alleviating pain and reducing secondary infection. In West Africa, palm oil, kerosine or a concoction of leaves are often placed over the ulcer. In Pakistan, treatments frequently observed include the application of the leaves o f the desert plant Calotropis sp, onion and soap pastes, pulverized grass, cattle excreta mixed with various oils, mud, dough and scorpion biles. It is worth mentioning that these procedures are fraught with many dangers and complications (Rab, 1991). Since the 1960s however, three compounds have been reported to have some effects on the emerging adult worm. These are Niridazole (at 25 mg/kg body wt, daily for 10 days), Thiabendazole (at 50 mg/kg body wt, daily for 7 days) and Metronidazole (400 mg/kg body wt, for 10 to 20 days). These drugs produce symptomatic relief of pain and pruritus, thereby 26 University of Ghana http://ugspace.ug.edu.gh hastening the expulsion of worms to a certain degree. They have however no effect on the pre­ emerging worms, and it appears that these compounds act primarily against host reaction, as their anti-inflammatory properties reduce the intensity o f tissue reaction around the worm's cuticle. Her;ce, none o f them is of any value in the prevention o f the disease. Also, Rab (1991) described a new method of worm expulsion. Here, the patient is put on a 5-day course of an antibiotic, Ampiclox, and an anti-inflammatory drug, Chymoral in their recommended therapeutic doses. Gauze bandages are then applied to ulcers with emerging worms and kept moist continuously by means of a small tube attached to a container filled with water. Alternatively, patients are advised to keep the bandages soaked and wet all the time. These antibiotics and the anti-inflammatory drugs reduce the severity of infection and inflammation around the worm cuticle, thereby enabling the almost empty bag of worms to be pulled out with relative ease. This simple method of worm extraction can not however be regarded as treatment of the disease. Nevertheless, it relieves the patients of their pain and misery, and thus reduces the period of immobilization as well as the number o f worm carriers who serve as sources of transmission. The method is therefore a simple aid that can be envisaged as part of a multifaceted approach to control Guinea worm and can therefore play an important role in eradication programmes. In an attempt to find out the efficacy of some herbal preparations in the treatment of Dracunculiasis, a study sponsored by UNICEF, the Danish Bilharziasis Laboratory (DBL) and Global 2000 was conducted by a three-man medical team in Ghana in 1995. This team recommended the use of the following herbs in Guinea worm treatment. Azadirachta indica (Neem tree), Carica papaya (male Pawpaw), Xanthosoma spp. (Cocoyam leaves), and Jatropha curcas ("nkrangyedua" leaves). The rest are; Desmodium celutigum ("ananse nkatee"), Nicotina lobaccum (tobacco leaves), Beqiaertrodendron magalismonanum ("liofonofo"), and Piper umbrellatum ("mumuaha"). These herbal preparations help expel the worms within three days. 27 University of Ghana http://ugspace.ug.edu.gh Thus, the early expulsion is very important because it reduces the possibility o f contaminating the sources of drinking water, thereby breaking transmission. (ii) Surgery; Guinea worms have been wound on a stick since antiquity. Kuchenmeister and Zum (1878-81) believed the fiery serpents of brass placed on a staff by Moses was an indication to the Israelites of how to deal with this affliction. This procedure is usually an essential part of treatment even today. Provided bacterial infection or other complications have not occurred, then regular winding out of the worm on a small stick (usually forked), combined with sterile dressing and acriflavine cream results in its complete expulsion in about three weeks with little pain or inconvenience (Muller, 1970). Surgical removal o f the worm after local anaesthesia is also widely done in most endemic countries these days. In Ghana, the GWEP has trained nurses and medical assistants in the endemic villages to surgically remove worms if the outline can be seen or palpated. This is the best method of case containment. 2.5.4 Vector Control: The provision of permanent safe drinking water in many areas has multiple constraints such as expense involved, length of time needed for construction and so forth. Nevertheless, transmission of Dracunculiasis can be interrupted in endemic villages by periodic chemical treatment of drinking water sources to kill the Cyclops. This method has often been advocated but rarely attempted, partly because o f the cost, but also because of the lack of basic epidemiological knowledge necessaiy to make such treatment effective. In this light, steam treament of step-wells was suggested by Leiper in 1912, 28 University of Ghana http://ugspace.ug.edu.gh Potassium permanganate and Quicklime by Turhud (1919) and Davis (1913) respectively. Later, Ramarkrishnan and Rathnaswamy (1953), found in the laboratory that lOppm of DDT caused 100% mortality of Cyclops in 48 hours. Following this, and using a single application o f DDT at this dilution, Nugent and co-workers (1955) reduced the incidence o f Guinea worm markedly (from 26.5 to 6 %) in five out o f seven villages in an area in Southern Ghana (Scott, 1959). In recent years, many compounds have been discovered that are effective as molluscicides or insect larvicides, and it was thought that some of these could as well be effective against Cyclops. Most of these substances are not only likely to be inexpensive in the quantities required, but also available in suitable formulations (Muller, 1971). To elucidate this, Manonmani et a l (1989), studied the susceptibilities of Mesocyclops to different insecticides. These insecticides included the organochlorine compounds: DDT, and BHC; the organophosphorus compounds: Dichlorvos, Temephos/ABATE, Fenitrothion, Zolone, Fenthion, Methylparathion, Phorate, Phosphamidon, Monocroptophos and Oxydemeton-methyl; the carbamate compounds: Carbendazin Carbanyl and Carbofuran. Also tested were the synthetic pyrethroid Permethrin; the insect growth regulator Methoprene; and the cyclodiene compound Aldrin. These insecticides produced remarkable susceptibility levels on the Cyclops. The difference in toxicities could have been due to several factors such as species, relative humidity and other ecological and geographic conditions. Considering the highly effective compounds, the study group was to realise that Permethrin ranked first followed by Dichlovos, Temephos, DDT, Carbendazin, Fentrothion, Zolone, and Aldrin in order of potency. Although most o f these insecticides proved effective against Mesocyclops spp, limitations do exist in their use in the field as most of them are deleterious to non-target organisms and mammals. Considering biosafety, Temephos/ABATE in the form of granular formulations is recommended for use as the most promising compound for the control o f Cyclops in Guinea 29 University of Ghana http://ugspace.ug.edu.gh worm infested areas. ABATE has the added advantage of easy applicability and safety to non­ target organisms and persons handling it (Manonmani et al., 1989). It is worth mentioning that the quest for a chemical agent for the control of Cyclops has been going on for a long time. As early as 1931, Davis carried out experiments in the Mongalla Province of the Sudan to find out the action of various agents on Cyclops. These chemicals included NaOH, KOH, HC1, Bleaching Powder, Potassium permanganate, Quicklime, Builders slaked lime andN aH C 03 (Davis, 1931). 2.6.0 STUDY OBJECTIVES. Dracunculiasis is caused by the Guinea worm, Dracunculus medinensis. L., and is endemic in parts of Africa and Asia. The vectors are commonly referred to as "Cyclops", but D. medinensis exhibits a high level of host specificity and only a few species act as vectors in nature. Recent progress in copepod systematics has refined the level o f taxonomic resolution of these freshwater copepods, and it is now known that, the all famous and well acclaimed universal vector species, Mesocyclops leukarti does not in fact occur in either Africa or India (Kiefer, 1981; Van de Velde, 1984). There is therefore the need to record these taxonomic changes, review earlier records and to update the nomenclature of the hosts wherever possible (Boxshall and Braide, 1991). The purpose of this study is therefore; (1) To identify and record the freshwater cyclopoid copepods in some village in the West Akim District of Ghana, where GW is endemic, including those that act as vectors of Dracunculiasis, and to document their current names, (2) To evaluate the value of ABATE as a Cyclopscide, and (3) To identify and investigate the socio-cultural practises of the indigenes that are of relevance to the transmission of the disease. 30 University of Ghana http://ugspace.ug.edu.gh Chapter 3 3.0 MATERIALS AND METHODS. 3.1.0 FIELD STUDIES. 3.1.1 Study area and features of sampling sites. The study was carried out in three villages (Tiokrom, Dzakpatra and Mepom) in the East Akim District o f the Eastern Region of Ghana (Figure 1). Whilst Tiokrom and Dzakpatra are small settlements, Mepom is a sub-urban settlement. Both Tiokrom and Mepom are accessible by main roads while Dzakpatra is quite remote. The terrain is coastal savannah with extensive brush but few trees. Agriculture is the primary occupation for subsistence, with the major crops being cassava, maize (com) and beans. Some farmers also produce tomatoes, okra, peppers and fruits on a small scale as a cash crop. The average annual rain fall is 48 inches with heavy rains in May to June, and a smaller peak in October. The predominant occupation is farming; 6 8 % of the adult males are farmers and 12.7% are labourers (Belcher et al., 1975). All the three villages were observed to use water sources which vary seasonally. During the rains water is collected and stored in pots and basins. In the long dry season, November to May, drinking water is obtained from ponds. Unlike Dzakpatra and Tiokrom which have been declared as Guinea worm endemic villages by the Guinea Worm Eradication Programme, Mepom is not. It is rather a village at the outskirts of the town (about 1km from Kwesi Acheampong known as Gahia Korpe) that experienced an almost 31 University of Ghana http://ugspace.ug.edu.gh 100% infection in 1994. The residents of Mepom though a sub-urban settlement, depend on four different ponds for water, with all hitherto stand-pipes (with water pumped from Accra) broken down for over ten years now. 3.1.2 Pond Morphometry. The volume of water in the study ponds was estimated every month on each visit. This was done by a relatively simple method using a piece of graduated nylon rope and a meter-rule. The averages of length (L), width (W) and depth (D) of the pond were taken by placing transects 50cm apart. Thus, the estimated capacity o f the pond at any particular time was calculated by multiplying the measured averages. That is; VOLUME = ( L x W x D ) m3. 3.1.3 Estimation of Cyclops density: In estimating the number of Cyclops in a known volume of water taken at the surface of a pond, the following method proved simple and satisfactory. It is basically a replicate o f that used by Onabamiro (1954), in estimating the relative cyclopoid copepod densities per 10 litres o f water. A wide mouthed plastic container o f volume 4 litres was lowered into the water at the contact site and scooped. The water fetched was then filtered using a monofilament filter o f mesh size 70 fim. The Cyclops trapped were then washed into a beaker with the aid o f a wash-bottle. This was repeated four times and the collected samples fixed immediately in 10% formalin separately and brought to the laboratory for analysis. The average number of Cyclops per unit volume of water was then determined. Since our main concern was the relative densities, the apparatus proved quite satisfactory. Secondly, the method of filtration is similar to that used by the women to fill their pots and basins. The sampling was done once every month for each pond to monitor the population changes of the Cyclops with time and/or season. 32 University of Ghana http://ugspace.ug.edu.gh 3.1.4 Retrospective Studies on Dracunculiasis in the area. The prevalence of Dracunculiasis in the study area was ascertained by the use o f a questionnaire (Appendix A). In this respect, three basic parameters implicated in the disease transmission were investigated, viz: (1) Human Behaviour. (2) The living conditions of the people. (3) The people’s knowledge of the disease. The questionnaire was administered by random sampling to investigate the incidence o f the disease by sex, age, occupation, month as well as the socio-cultural practices o f the people that aid in the disease transmission. 3.2.0 LABORATORY WORK. 3.2.1 Identification of Cyclops species. Having recorded the Cyclops count per litre of water as in 3.1.3 above, the specimens were preserved in 70% ethyl alcohol. The identification o f the Cyclops was done using a phase-contrast microscope (Model: Optiphot-2; Nikon, Japan). Here, only mature and gravid females were examined and identified accordingly. This was to make sure that specimens used in the identification process were matured, since the key uses morphological features on the body. The key used in the identification exercise was that prepared by Annette Olsen (1993), o f the Danish Bilharziasis Laboratory- ’’VECTORS OF GUINEA WORM DISEASE IN TROPICAL AFRICA; A KEY TO THE SPECIES OF THERMOCYCLOPS AND MESOCYCLOPS" (Appendix D). I find this key quite adequate because a review of West African records reveal that D. medinensis is transmitted 33 University of Ghana http://ugspace.ug.edu.gh in tropical Africa by seven species of Cyclops. There are four Thermocyclops spp, two Mesocyclops spp and a Metacyclops sp (Johnson el al, 1990). The use of this key was supplemented by another key prepared by Boxshall and Braide (1991)- "THE FRESHWATER CYCLOPOID COPEPODS OF NIGERIA, WITH AN ILLUSTRATED KEY TO ALL SPECIES". The two keys use distinct morphological features on such body parts as the fifth pair of legs, the caudal rami, the antennae, the seminal receptacle, the maxillary palpi, the total body length and the relative lengths of the body segments. The identification process involved observing the specimens in water-free glycerine on a clean slide under a microscope. The Cyclops were then teased with a dissecting pin until the structure under investigation was appropriately orientated or positioned for observation. 3.2.2 Breeding and investigation of species specific toxicities: To obtain enough Cyclops for species specific tests, the species were reared in aquarium tanks measuring 49 by 35 by 19cm. Here, a single gravid female Cyclops was selected using a Pasteur pipette and washed several times with tap water in a petri-dish. This was to ensure that no nuplaii or eggs of other Cyclops species were carried along with the adult Cyclops into the breeding tank. The petri-dishes were placed over a dark background to facilitate easy access, handling and observation of the Cyclops. The gravid female was then transferred into a beaker containing 500ml tap water. The nauplii hatching from the eggs were then reared in aquarium tanks containing tap water and fed on cow dung infusion and the green algae Cladophora spp as in 3.2.2 above. The water in the tanks was aerated for 15 minutes daily and changed every fortnight until the colony could provide enough adult Cyclops for the tests. 34 University of Ghana http://ugspace.ug.edu.gh 3.2.3 Pond Culture of Cyclops. In order to obtain consistent experimental results, it was desirable to maintain colonies of Cyclops in the laboratory. Thus, a colony of mixed species was maintained in a fenced pond in the Zoology Department, University of Ghana. This pond measured 113cm by 88cm by 23cm and could contain a maximum of 0.23 cubic metres of water. The main advantage o f maintaining the pond outside the laboratory was that natural field conditions were simulated. This pond was located directly under a big tree and fringed by grasses. Also, the pond contained the filamentous green algae Cladophora spp. and other floating and submerged vegetation such as Lemna and Ceratophyllum. The original stock of the cultured Cyclops was obtained from the villages where \guinea worm disease is endemic. After two weeks, the pond became self-sustaining, and had a good growth of algae and flagellates. Thus, no food was introduced artificially. It was also possible to rear large numbers of Cyclops in aquarium tanks containing water at room temperature (25-29 °c). These tanks, were aerated for 15 minutes everyday and the Cyclops fed on a mixture of cow dung infusion and the filamentous green algae Cladophora spp. The dung infusion was prepared by dissolving 50mg of fresh/wet dung in 1000ml of pipe water and maintained at room temperature in the laboratory. The preparation was then monitored until the ciliate count per drop of the infusion (using a Pasteur pipette) was 120-150. This was the maximum count obtained from a preliminary study within 9-11 days, after which the count was observed to decline. Also the pH of the tanks containing the Cyclops colonies was observed to be between 6.5 and 6.9, thus care was taken when adding the infusion so as to maintain this pH range. The infusion was added to the aquarium tanks at 25ml per week and the water changed every fortnight. 35 University of Ghana http://ugspace.ug.edu.gh 3.2.4. Toxicity testing: The chemical o f choice, Temephos (ABATE, ABATHION, ABAT, S WEB AT, NIMITEX or BIOTHION) 0 - 0 - 0 '-O^tetramethyl-O-O’-thiodi-P-phenylene phosphorothiote, is an organophosphorus compound of minimal toxicity. It has a molecular weight o f 466.5, is available in emulsifiable concentrate, as a brown viscous liquid, or a white crystalline dispersable powder with a granular formulations (1 S.G.). It has a specific gravity o f 1.32, melts at 30 to 30.5 °C, is insoluble in water and is stable indefinitely at room temperature (Worthing, 1979; Sastry et a l , 1978). 36 The structural formula o f ABATE is: Thus: C6H20O6P2S3, with a molecular weight of (466.5) ABATE is eliminated from the body in unchanged and conjugated form both in the faeces and the urine after oral administration. Conjugated forms are in the bulk o f the urine elimination products. ABATE probably acts just like any other organophosphorus compound, inhibiting irreversibly the cholinesterase enzyme by alkyl phosphorylation, thus causing paralysis o f the Cyclops and ultimate death (Sastry et al., 1978). University of Ghana http://ugspace.ug.edu.gh A preliminary susceptibility test was conducted at doses ranging from 0.1 to 2.05ppm for rough dose estimation with two replicates for each dosage, along with appropriate controls. Observations were recorded for mortalities of Cyclops after 24 and 48 hrs. Six doses were selected (0.25, 0.50,0.75,1.00,1.50 and 2.00) for further experimentation. The tests were carried out in 50ml petri-dishes containing batches of 20 adult Cyclops and kept at room temperature. Mortalities were determined after 24 and 48 hours using a light microscope. "Death" of a Cyclops was defined here as inability to move after being touched with a Pasteur pipette. The LC values were then worked out using a computer programme (Program Malaria in vitro Logdose Response). Further, different tests of statistical analysis were carried out to ascertain the validity or otherwise o f various null hypotheses which included the following: (1) The mortality rate o f Cyclops dosed with ABATE is independent of the species o f Cyclops). (2) The mortality rate of Cyclops is independent of the age/state o f ABATE. (3) The mortality rate of Cyclops is independent of the concentration o f ABATE used. These tests of significance are: (1) Two-factor Analysis of Variance (ANOVA). (2) The Multi-range analysis of Variance (LSD). (3) The Chi-square (%2) test o f significance. 37 University of Ghana http://ugspace.ug.edu.gh In addition to the tests on the laboratory reared Cyclops, specimens obtained from the field were also tested. In all these tests, the water used in preparing the solutions was obtained from the culture pond and filtered using a monofilament filter of mesh size 70 [im. This filtered water was further passed through a column of pure cotton wool parked to a height o f 30cm in a perspex tube of height 92cm and diameter 4.5cm. The results of these tests are as shown Appendix B. 38 University of Ghana http://ugspace.ug.edu.gh Chapter 4 39 4.0 RESULTS. 4.1.0 FIELD STUDIES. 4.1.1 Pond Morphometry. The estimated volume of water in the various ponds throughout the period o f study is shown in Table 5. Plates 2-5 show the physical features/characteristics of the ponds in the rainy and dry seasons. 4.1.2 Seasonal Variation in Cyclops Density. Table 4 illustrates the population densities o f Cyclops in the sources of drinking water (ponds) in the study areas with time and/or season . The trend is generally that of a periodic rise and fall in numbers with time and/or season. In all the ponds investigated, there was also a decline in the number o f Cyclops per litre o f water from June to August and then a considerable increase in September and October after which a drastic fall in Cyclops densities was observed, the minimum occurring in February. With the exception o f the Dzakpatra pond which dried up in March, all the others recorded their lowest volumes in February (Plates 2-5). These results are illustrated in Figure 4. University of Ghana http://ugspace.ug.edu.gh 4.1.3 Prevalence of Guinea worm disease in the areas. 4.1.3.1 Tiokrom. 4.1.3.1a Prevalence by Age and Sex. The age and sex distribution of those who have ever suffered from Dracunculiasis in the study area within the last three years (1994-1996) was ascertained by the use o f a questionnaire. The results obtained from the above village (Tiokrom) are shown in Table 7a and illustrated in Figure 5a. The salient features are as follows: (1) An overall prevalence of 26.9% (14.6% in males and 12.3% in females). (2) The highest prevalence in both sexes occurred in the 16-20 age group (33.3% for males and 66.7% for females). The next highest was in the 11-15 year age group, with 30.8% for males and 45.5% for females. (3) The lowest prevalence in both sexes was in the 6-10 year age groups, with no cases in the 0-6 and above 50 year age groups. Whilst the youngest person to have suffered from Guinea worm was six years of age, the oldest was forty-eight years old at the time o f infection. 4.1.3.1b Prevalence by Occupation. The highest prevalence by occupation occurred among farmers (48.7%) followed by Housewives(25.6%), and the lowest was among pupils/school children (5.1%). This is shown in Table 7b and illustrated in Figure 5b. 40 University of Ghana http://ugspace.ug.edu.gh 4.1.3.1c Monthly Variation in Prevalence. Of all the cases, 82% became manifest between February and April, the peak occurring in April (34.3%). These are as shown in Table 7c and Figure 5c. 4.1.3.Id Site of Worm Emergence. The preferred sites of lesions produced on the body by emerging adult guinea worms are summarised in Table 7d and illustrated in Figure 5d. Of all lesions, 31% occurred on the lower limbs, with over 50% appearing on the ankle and feet. 4.1.3.2 Dzakpatra 4.1.3.2a Prevalence by Age and Sex. The age and sex distribution of Dracunculiasis in Dzakpatra between 1994 and 1996 is presented in Table 8a and illustratd in Figure 6a. The total percentage infection was 49.4%. 45.3% o f these occurred in males whilst the percentage infection in the females was as high as 53.8%. The age groups with the highest prevalence rates in both sexes were the 6-20 year age group in the males and the 11-30 year age group in the females. There were no cases among the 0-5 and >50 years age groups in both sexes. 4.1.3.2b Prevalence by Occupation. The occupational distribution of guinea worm in the village is summarised in Table 8b and illustrated in Figure 6b. Here, the highest infection rate was among the pupils or school children (33%). This is the exact opposite of the situation in Tiokrom. The second highest rate of infection was among farmers (11%). 41 University of Ghana http://ugspace.ug.edu.gh 4.1.3.2c Monthly Variation in Prevalence. Almost all the cases of Guinea worm attack appear to have occurred between January and May (95.2%), with a few cases in October. The highest prevalence rate was in March (36.9%), with no cases in the other months. These are shown in Table 8c and illustrated in Figure 6c. 4.1.3.2d Site of W orm Emergence. As found in Tiokrom, the observed preferred site of emerging female guinea worms was the lower limbs, especially the ankle and feet. 51.1% o f all lesions were observed to occur on the feet and ankle. This is shown in Table 8d and illustrated in Figure 6d. 4.1.3.3a Mepom (Mataligu section). There were no cases recorded in this part/section of the village. The results obtained are presented in Table 9a. 4.1.3.3b Mepom (Kwesi Acheampong section). The only cases recorded in this section of the village, (a typical settlement for Palm oil extraction) was observed to have been imported from Gahia Korpe, another settlement at the outskirts of Mepom which recorded an almost 100% prevalence in 1994. The results are shown in Table 9b. This village can however be considered as a receptive area/zone since the implicated vector species of Dracunculiasis was recovered from ponds in this village. 42 University of Ghana http://ugspace.ug.edu.gh 4.2.0 SOCIO-CULTURAL ASPECTS OF GUINEA WORM DISEASE. 43 4.2.1 Beliefs, attitudes and values. In this study, the most astonishing revelation was the peoples unwillingness to change their insanitary habits. Thus, even though the Guinea Worm Eradication Programme (GWEP) is quite active in these areas to improve their lot, this resistance to change could be responsible for the continued prevalence and spread of the disease. There is also a considerable degree of ignorance concerning the origin and transmission of the disease. This ignorance o f the aetiology of Dracunculiasis is further compounded by the long prepatent period of the malady. These peasants therefore cannot readily see the relationship between drinking contaminated pond water and suffering from Guinea Worm disease 9-12 months later. In general however, most people linked the disease with unclean water, though with different interpretations of what they