Browsing by Author "Appawu, M.A."

Now showing 1 - 20 of 23

Anaemia caused by asymptomatic plasmodium falciparum infection in semi-immune african schoolchildren.
(1999) Kurtzhals, J.A.L.; Addae, M.M.; Akanmori, B.D.; Dunyo, S.; Koram, K.A.; Appawu, M.A.; Nkrumah, F.K.; Hviid, L.
A cohort of 250 Ghanaian schoolchildren aged 5-15 years was followed clinically and parasitologically for 4 months in 1997/98 in order to study the effect of asymptomatic Plasmodium falciparum infections on haematological indices and bone-marrow responses. Of the 250 children 65 met the predefined study criteria. Thus, 14 children were parasite-free throughout (group 1), 44 had P. falciparum in all blood samples collected but no symptoms of malaria (group 2), and 7 had 1 malaria attack during the study period (group 3). At the end of the study the mean haemoglobin (Hb) level in group 1 was 123 g/L, significantly higher than the value of 114 g/L in groups 2 and 3 (P < 0.02, adjusted for age and splenomegaly). The low Hb in group 2 was associated with subnormal plasma iron. Low Hb was associated with elevated erythropoietin (EPO) levels, and there was a positive correlation between EPO and reticulocyte counts. However, the reticulocyte response to EPO was more pronounced in uninfected than in infected children, suggesting a partial interference with erythropoiesis in asymptomatic infections. Children with asymptomatic infections had significantly higher plasma levels of tumour necrosis factor than uninfected children (geometric means 50 ng/L and 27 ng/L, respectively, P < 0.001) and this cytokine may contribute to bone-marrow suppression and disturbed iron metabolism. We suggest that asymptomatic malaria leads to a homeostatic imbalance in which erythrocyte loss due to parasite replication is only partially compensated for by increased erythropoiesis. The consequences of the reduced Hb levels on the development and cognitive abilities of children with asymptomatic infections, and the risk of precipitation of iron deficiency, deserve further study and should be considered in malaria control programmes that aim at reducing morbidity rather than transmission.
Assessing the Presence of Wuchereria bancrofti Infections in Vectors Using Xenomonitoring in Lymphatic Filariasis Endemic Districts in Ghana
(Tropical Medicine and Infectious Disease, 2019-03-13) Dadzie, S.K.; Pi-Bansa, S.; Osei, J.H.N.; Kartey-Attipoe, W.D.; Elhassan, E.; Agyemang, D.; Otoo, S.; Appawu, M.A.; Wilson, M.D.; Koudou, B.G.; De Souza, D.K.; Utzinger, J.; Boakye, D.A.
Mass drug administration (MDA) is the current mainstay to interrupt the transmission of lymphatic filariasis. To monitor whether MDA is effective and transmission of lymphatic filariasis indeed has been interrupted, rigorous surveillance is required. Assessment of transmission by programme managers is usually done via serology. New research suggests that xenomonitoring holds promise for determining the success of lymphatic filariasis interventions. The objective of this study was to assess Wuchereria bancrofti infection in mosquitoes as a post-MDA surveillance tool using xenomonitoring. The study was carried out in four districts of Ghana; Ahanta West, Mpohor, Kassena Nankana West and Bongo. A suite of mosquito sampling methods was employed, including human landing collections, pyrethrum spray catches and window exit traps. Infection of W. bancrofti in mosquitoes was determined using dissection, conventional and real-time polymerase chain reaction and loop mediated isothermal amplification assays. Aedes, Anopheles coustani, An. gambiae, An. pharoensis, Culex and Mansonia mosquitoes were sampled in each of the four study districts. The dissected mosquitoes were positive for filarial infection using molecular assays. Dissected An. melas mosquitoes from Ahanta West district were the only species found positive for filarial parasites. We conclude that whilst samples extracted with Trizol reagent did not show any positives, molecular methods should still be considered for monitoring and surveillance of lymphatic filariasis transmission.
Bancroftian filariasis in an irrigation project community in southern Ghana.
(1999) Dzodzomenyo, M.; Dunyo, S.K.; Ahorlu, C.K.; Coker, W.Z.; Appawu, M.A.; Pederson, E.M.; Simonsen, P.E.
An epidemiological study to document the endemicity and transmission characteristics of bancroftian illariasis was conducted in an irrigation project community in southern Ghana. In a 50% random sample of the population, the prevalence of microfilaraemia was 26.4% and the geometric mean microfilarial intensity among positives was 819 microfilariae/ml of blood. Hydrocoele was found in 13.8% of the males aged ?18 years, and 1.4% of the residents examined, all females, had lymphoedema/elephantiasis. Detailed monitoring of the microfilarial intensity in 8 individuals over a 24-h period confirmed its nocturnal periodicity with a peak at approximately 0100 hours. The most important vector was Anopheles gambiae s.l., followed by An. funestus. The abundance of these mosquitoes and their relative importance as vectors varied considerably between the wet and the dry season. Opening of the irrigation canals late in the dry season resulted in a remarkable increase in the population of An. gambiae (8.3% of which carried infective filarial larvae) to levels comparable to those seen during the wet season, suggesting that the irrigation project is responsible for increased transmission of lymphatic filariasis in the community.
Biology And Ecology Of The Predatory Mosquito, Culex (Lutzia) Tigripes Grandpre And Charmoy (Diptera:Culicidae) In South-Eastern Ghana.
(University of Ghana., 1990) Appawu, M.A.
Culex (lutzia) tigripes Grandpré and charmoy is a larvivorous mosquito with all instars of the larvae feeding primarily on the immature stages of other mosquito species found in their habitats. They breed in a wide range of water bodies but seem to prefer those already containing larvae of other mosquito species. The fluctuations in the population of the larval instars and pupae were studied by weekly sampling throughout the year. It breeds throughout the year and the population peaks either coincide with or follow that of the preys; with both fluctuating with the rainfall. The larval densities of c. (L) tigripes were very small compared with those of other mosquito species; thus only 392-952 larvae of the predator were collected in the peak periods of May to July compared to 2786-8676 larvae of the prey mosquitoes. No significant correlation was noted between variations in the numbers of C. (L) tigripes and the following physical and chemical properties of the breeding water: pH, Temperature, Chloride, Dissolved Oxygen and Total Alkalinity. Life-table studies showed the existence of high mortalities in the later stages of the predator. Starting from egg rafts collected from the field and providing C. quinguefasciatus larvae as the larval food and chicken as a source of blood, a colony of C. (L) tigripes was started but poor insemination appeared to be the major obstacle to successful and permanent colonization. vi Artificial insemination and copulation were also not successful.The optimum larval developmental temperature was 30°C, and 32°C for the pupae. Even though more prey larvae were consumed between 30-32°C than between 20-26°C, there was a reduction in weight of the final instar larvae and pupae at the higher temperatures. Depending on temperature each predator consumed between 160-229 larvae of C.quinguefasciatus during its entire larval development. With this rate of prey destruction, the predator can have big impact on the prey population despite the low proportion (1:7-9) of predator to prey.When larvae of C. (L) tigripes were reared on three non living diets namely; Cerelac infant cereal, dog biscuit and milk casein, the developmental period of all instars was greatly prolonged and only one larva, reared on milk casein developed into adult mosquito. The weights of the final instar larvae reared on non-living diets were significantly lower than those reared on larvae of C. quinquefasciatus. Culex (L) tigripes has well developed mandibles and serrated mouthbrushes for effective predation. The effect of the following factors on prey capture were studied: mobility, size, posture, the density and the extent to which prey and predator occur simultaneously in the same habitat. Ae. aegypti which moves more frequently was more preyed upon than An. gambiae and C. quinquefasciatus, and similarly, C.quinquefasciatus was selected more than chironomid. The strong integument of the pupae together with their large vii sizes, spherical shape, posture in the water and ability to move quickly afforded them a better chance of escaping predation by C. (L) tigripes. The effect of prey stage, predator stage and prey density on the predation rate was investigated using (C. quinquefasciatus) as prey.It was shown that the rate of predation increased with increase in the size of the predator and the density of the prey but decreased with increase in prey size. The functional response of the predator to changing prey densities followed Hollings type II model. The handling time of the predatory larvae on preys decreased as the length of time in which they were deprived of food was increased but the daily prey consumption was not affected. Cannibalism occurred in all larval stages of the predator. The rate was higher among the early instars; was lower in the presence of mosquito prey and increased with crowding.
Characterization of malaria transmission by vector populations for improved interventions during the dry season in the kpone-on-sea area of coastal Ghana
(Parasites and Vectors, 2012) Tchouassi, D.P.; Quakyi, I.A.; Addison, E.A.; Bosompem, K.M.; Wilson, M.D.; Appawu, M.A.; Boakye, D.A.
Background: Malaria is a major public health problem in Ghana. We present a site-specific entomological study of malaria vectors and transmission indices as part of an effort to develop a site for the testing of improved control strategies including possible vaccine trials. Methods. Pyrethrum spray catches (PSC), and indoor and outdoor human landing collections of adult female anopheline mosquitoes were carried out over a six-month period (November 2005 - April 2006) at Kpone-on-Sea, a fishing village in southern Ghana. These were morphologically identified to species level and sibling species of the Anopheles gambiae complex further characterized by the polymerase chain reaction (PCR). Enzyme-linked immunosorbent assay was used to detect Plasmodium falciparum mosquito infectivity and host blood meal sources. Parity rate was examined based on dilatation of ovarian tracheoles following dissection. Results: Of the 1233 Anopheles mosquitoes collected, An. gambiae s.l. was predominant (99.5%), followed by An. funestus (0.4%) and An. pharoensis (0.1%). All An. gambiae s.l. examined (480) were identified as An. gambiae s.s. with a majority of M molecular form (98.2%) and only 1.8%S form with no record of M/S hybrid. A significantly higher proportion of anophelines were observed outdoors relative to indoors (χ 2=159.34, df=1, p<0.0000). Only An. gambiae M molecular form contributed to transmission with a high degree of anthropophily, parity rate and an estimated entomological inoculation rate (EIR) of 62.1 infective bites/person/year. The Majority of the infective bites occurred outdoors after 09.00pm reaching peaks between 12.00-01.00am and 03.00-04.00am. Conclusion: Anopheles gambiae M molecular form is responsible for maintaining the status quo of malaria in the surveyed site during the study period. The findings provide a baseline for evidence-based planning and implementation of improved malaria interventions. The plasticity observed in biting patterns especially the combined outdoor and early biting behavior of the vector may undermine the success of insecticide-based strategies using insecticide treated nets (ITN) and indoor residual spray (IRS). As such, novel or improved vector interventions should be informed by the local malaria epidemiology data as it relates to vector behavior. © 2012 Tchouassi et al.; licensee BioMed Central Ltd.
Characterization of malaria transmission by vector populations for improved interventions during the dry season in the Kpone-on-Sea area of coastal Ghana
(2012-09-26) Tchouassi, D.P.; Quakyi, I.A.; Addison, E.A.; Bosompem, K.M.; Wilson, M.D.; Appawu, M.A.; Brown, C.A.; Boakye, D.A.
Abstract Background Malaria is a major public health problem in Ghana. We present a site-specific entomological study of malaria vectors and transmission indices as part of an effort to develop a site for the testing of improved control strategies including possible vaccine trials. Methods Pyrethrum spray catches (PSC), and indoor and outdoor human landing collections of adult female anopheline mosquitoes were carried out over a six-month period (November 2005 - April 2006) at Kpone-on-Sea, a fishing village in southern Ghana. These were morphologically identified to species level and sibling species of the Anopheles gambiae complex further characterized by the polymerase chain reaction (PCR). Enzyme-linked immunosorbent assay was used to detect Plasmodium falciparum mosquito infectivity and host blood meal sources. Parity rate was examined based on dilatation of ovarian tracheoles following dissection. Results Of the 1233 Anopheles mosquitoes collected, An. gambiae s.l. was predominant (99.5%), followed by An. funestus (0.4%) and An. pharoensis (0.1%). All An. gambiae s.l. examined (480) were identified as An. gambiae s.s. with a majority of M molecular form (98.2%) and only 1.8% S form with no record of M/S hybrid. A significantly higher proportion of anophelines were observed outdoors relative to indoors (χ 2 = 159.34, df = 1, p < 0.0000). Only An. gambiae M molecular form contributed to transmission with a high degree of anthropophily, parity rate and an estimated entomological inoculation rate (EIR) of 62.1 infective bites/person/year. The Majority of the infective bites occurred outdoors after 09.00 pm reaching peaks between 12.00-01.00 am and 03.00-04.00 am. Conclusion Anopheles gambiae M molecular form is responsible for maintaining the status quo of malaria in the surveyed site during the study period. The findings provide a baseline for evidence-based planning and implementation of improved malaria interventions. The plasticity observed in biting patterns especially the combined outdoor and early biting behavior of the vector may undermine the success of insecticide-based strategies using insecticide treated nets (ITN) and indoor residual spray (IRS). As such, novel or improved vector interventions should be informed by the local malaria epidemiology data as it relates to vector behavior.
Control of Parasitic Diseases through School-based Health Education and Deworming: A five years activities in Ada-Foah, Ghana. X European Multicolloquium of Parasitology – EMOP 10 Paris
(France CN, pp. 103-107, 2008) Bosompem, K.A.; Wilson, M.D.; Anyan, W.K.; Awazawa, T.; Hanafusa, D.; Boakye, D.A.; Appawu, M.A.; Ayi, I.; Boamah, D.; Asigbee, J.K.; Quartey, J.K.; Ogiwara, H.; Ohta, N.; Ofori-Adjei, D.; Nyarko, A.; Takeuchi, T.
KAP and parasitological surveys were conducted (in 2002, 2005 and 2007) among primary school children in the model site of West African Centre for International Parasite Control (WACIPAC) in Ghana. School-based health intervention was used as a means of controlling Soil Transmitted Helminths (STH) and Schistosomiasis. Comprehensive health promoting activities, including health education and mass deworming was conducted in all 10 primary schools in communities in the area. The KAP study showed that hygienic and de-worming practices and knowledge about de-worming had improved. Par asitlogical surveys also showed that the prevalence of both STH and schistosomiasis decreased sharply over the 5 years. Interestingly, knowledge related to the causes and transmission of parasitic diseases did not show improvement.
Detection of malaria sporozoites by standard ELISA and VecTest™ dipstick assay in field-collected anopheline mosquitoes from a malaria endemic site in Ghana.
(Tropical Medicine & International Health, 2003-10-22) Appawu, M.A.; Bosompem, K.M.; Dadzie, S.; McKakpo, U.S.; Anim-Baidoo, l.; Dykstra, E.; Fryauff, D.J.
We compared the VecTestTM dipstick assay for detection of Plasmodium sporozoites in Anopheles vectors of malaria with standard circumsporozoite (CS) microplate ELISA for detection of Plasmodium falciparum circumsporozoite protein (PfCSP) in Anopheles mosquitoes. Mosquitoes were collected from a malaria endemic site (Kassena Nankana district) in northern Ghana. Of 2620 randomly sampled mosquitoes tested, the standard CS-ELISA gave a sporozoite rate of 10.8% compared with 11.2% by VecTestTM, which was not statistically different (P = 0.66). Visual reading of the CS-ELISA results gave a sporozoite rate of 13.4%, which was higher than the other tests (P > 0.05). To allow a more objective evaluation of the sensitivity of the dipstick, an additional 136 known CS-ELISA-positive specimens were analysed. The prevalence of the test (including the additional samples) was 14.6% and 14.7% for CS-ELISA and dipstick, respectively (P > 0.05). The estimated prevalence by visual assessment of the CS-ELISA results was 17.5%. The relative specificity and sensitivity of the VecTestTM dipstick and visually read ELISA were estimated based on the CS-ELISA as a gold standard. The specificities of the dipstick and visual ELISA were high, 98.0% and 96.6%, respectively. However, the sensitivities of the two assays were 88.8% for VecTest and 100% for visual ELISA (P < 0.01). Concordance between VecTest and CS-ELISA was good (κ = 0.86). Similarly, there was a good concordance between the dipstick and the visually read ELISA (κ = 0.88). Extrapolating from PfCSP controls (titrated quantities of P. falciparum sporozoites), mean sporozoite loads of CS-ELISA-positive An. gambiae (286 ± 28.05) and An. funestus (236 ± 19.32) were determined (P = 0.146). The visual dipstick grades showed high correlation with sporozoite load. The more intense the dipstick colour, the higher the mean sporozoite load (+ = 108, ++ = 207, +++ = 290, r = 0.99, r2 = 1). The VecTest dipstick offers practical advantages for field workers needing rapid and accurate means of detection of sporozoites in mosquitoes.
Evaluation of piperonyl butoxide in enhancing the efficacy of pyrethroid insecticides against resistant Anopheles gambiae s.l. in Ghana
(Malaria Journal, 2017) Dadzie, S.K.; Chabi, J.; Asafu-Adjaye, A.; Owusu-Akrofi, O.; Baffoe-Wilmot, A.; Malm, K.; Bart-Plange, C.; Coleman, S.; Appawu, M.A.; Boakye, D.A.
Background: Malaria vector control methods involving the use of pyrethroids remain the strategies being used against malaria vectors in Ghana. These methods include the use of long-lasting insecticidal nets and indoor residual spraying in many areas in Ghana. However, there is evidence that pyrethroid resistance is widespread in many areas in Ghana. Synergists have been shown to be useful in inhibiting the enzymes that are responsible for the development of resistance and hence enhance the insecticide susceptibility of Anopheles gambiae sensu lato (s.l.) in many areas. The present study investigated the effect of piperonyl butoxide (PBO) on the susceptibility status of An. gambiae s.l. across some sentinel sites in Ghana. Methods: Three to five day old An. gambiae s.l. reared from larvae were used in WHO susceptibility tube assays. Batches of 20-25 female adult An. gambiae s.l. were exposed simultaneously to the insecticide alone and to the PBO + insecticide. The knock down rate after 60 min and mortality at 24 h were recorded. Results: Deltamethrin and permethrin resistance of An. gambiae s.l. was observed in all the sites in 2015 and 2016. The mortality after 24 h post exposure for deltamethrin ranged from 16.3% in Weija to 82.3% in Kade, whereas that for permethrin ranged from 3.8% in Gomoa Obuasi to 91.3% in Prestea. A significant increase in susceptibility to deltamethrin and less to permethrin was observed during both 2015 and 2016 years in most of the sites when An. gambiae s.l. mosquitoes were pre-exposed to PBO. Conclusion: Findings from this study showed that the use of PBO significantly enhanced the susceptibility of An. gambiae s.l. mosquitoes in most of the sentinel sites. It is recommended that vector control strategies incorporating PBO as a synergist can be effective in killing mosquitoes in the presence of deltamethrin and permethrin resistance. © 2017 The Author(s).
The impact of indoor residual spraying on Plasmodium falciparum microsatellite variation in an area of high seasonal malaria transmission in Ghana, West Africa
(2021) Argyropoulos, D.C.; Ruybal-Pesántez, S.; Deed, S.L.; Oduro, A.R.; Dadzie, S.K.; Appawu, M.A.; Asoala, V.; Pascual, M.; Koram, K.A.; Day, K.P.; Tiedje, K.E.
Here, we report the first population genetic study to examine the impact of indoor residual spraying (IRS) on Plasmodium falciparum in humans. This study was conducted in an area of high seasonal malaria transmission in Bongo District, Ghana. IRS was implemented during the dry season (November–May) in three consecutive years be tween 2013 and 2015 to reduce transmission and attempt to bottleneck the parasite population in humans towards lower diversity with greater linkage disequilibrium. The study was done against a background of widespread use of long-lasting insec ticidal nets, typical for contemporary malaria control in West Africa. Microsatellite genotyping with 10 loci was used to construct 392 P. falciparum multilocus infection haplotypes collected from two age-stratified cross-sectional surveys at the end of the wet seasons pre- and post-IRS. Three-rounds of IRS, under operational condi tions, led to a >90% reduction in transmission intensity and a 35.7% reduction in the P. falciparum prevalence (p < .001). Despite these declines, population genetic analysis of the infection haplotypes revealed no dramatic changes with only a slight, but significant increase in genetic diversity (He: pre-IRS = 0.79 vs. post-IRS = 0.81, p = .048). Reduced relatedness of the parasite population (p < .001) was observed post-IRS, probably due to decreased opportunities for outcrossing. Spatiotemporal genetic differentiation between the pre- and post-IRS surveys (D = 0.0329 [95% CI: 0.0209 – 0.0473], p = .034) was identified. These data provide a genetic explanation for the resilience of P. falciparum to short-term IRS programmes in high-transmission settings in sub-Saharan Africa.
Implementing a community vector collection strategy using xenomonitoring for the endgame of lymphatic filariasis elimination
(Parasites and Vectors, 2018-12) Pi-Bansa, S.; Osei, J.H.N.; Joannides, J.; Woode, M.E.; Agyemang, D.; Elhassan, E.; Dadzie, S.K.; Appawu, M.A.; Wilson, M.D.et.al.
Background The global strategy for elimination of lymphatic filariasis is by annual mass drug administration (MDA). Effective implementation of this strategy in endemic areas reduces Wuchereria bancrofti in the blood of infected individuals to very low levels. This minimises the rate at which vectors successfully pick microfilariae from infected blood, hence requiring large mosquito numbers to detect infections. The aim of this study was to assess the feasibility of using trained community vector collectors (CVCs) to sample large mosquito numbers with minimal supervision at low cost for potential scale-up of this strategy. Methods CVCs and supervisors were trained in mosquito sampling methods, i.e. human landing collections, pyrethrum spray collections and window exit traps. Mosquito sampling was done over a 13-month period. Validation was conducted by a research team as quality control for mosquitoes sampled by CVCs. Data were analyzed for number of mosquitoes collected and cost incurred by the research team and CVCs during the validation phase of the study. Results A total of 31,064 and 8720 mosquitoes were sampled by CVCs and the research team, respectively. We found a significant difference (F(1,13) = 27.1606, P = 0.0001) in the total number of mosquitoes collected from southern and northern communities. Validation revealed similar numbers of mosquitoes sampled by CVCs and the research team, both in the wet (F(1,4) = 1.875, P = 0.309) and dry (F(1,4) = 2.276, P = 0.258) seasons in the southern communities, but was significantly different for both wet (F(1,4) = 0.022, P = 0.005) and dry (F(1,4 ) = 0.079, P = 0.033) seasons in the north. The cost of sampling mosquitoes per season was considerably lower by CVCs compared to the research team (15.170 vs 53.739 USD). Conclusions This study revealed the feasibility of using CVCs to sample large numbers of mosquitoes with minimal supervision from a research team at considerably lower cost than a research team for lymphatic filariasis xenomonitoring. However, evaluation of the selection and motivation of CVCs, acceptability of CVCs strategy and its epidemiological relevance for lymphatic filariasis xenomonitoring programmes need to be assessed in greater detail.
Lymphatic filariasis in Ghana: Entomological investigation of transmission dynamics and intensity in communities served by irrigation systems in the Upper East Region of Ghana
(Tropical Medicine and International Health, 2001-07) Appawu, M.A.; Dadzie, S.K.; Baffoe-Wilmot, A.; Wilson, M.D.
We conducted an entomological study to document the effect of irrigation on the vectors and transmission dynamics of lymphatic filariasis in the Upper East Region of Ghana. Mosquitoes were collected by indoor spraying of houses in a cluster of communities located around irrigation projects (Tono and Vea) and others without reservoirs (Azoka). Anopheles gambiae s.s. was the dominant species and major vector, followed by An. funestus. Anopheles arabiensis constituted 9-14% of the An. gambiae complex but none were infective. Culex quinquefasciatus was also not infective in these communities. Chromosomal examinations showed that >60% (n = 280-386) of the An. gambiae s.s. in irrigated communities were Mopti forms whilst 73% (n = 224) in the non-irrigated area were Savannah forms. Infectivity rates (2.3-2.8 vs. 0.25), worm load (1.62-2.04 vs. 1.0), annual bites per person (6.50-8.83 vs. 0.47) and annual transmission potential (13.26-14.30 vs. 0.47) were significantly higher in irrigated communities.
Lymphatic filariasis in Ghana: Establishing the potential for an urban cycle of transmission
(Tropical Medicine and international Health, 2005) Gbakima, A.A.; Appawu, M.A.; Dadzie, S.; Karikari, C.; Sackey, S.O.; Baffoe-Wilmot, A.; Scott, A.L.
Lymphatic filariasis is a significant public health and economic problem in many tropical and subtropical regions. Unplanned urbanization leading to a lack of proper sanitary conditions has resulted in an increase in the urban-based transmission of a number of vector-borne diseases, including lymphatic filariasis. It has been well established that lymphatic filariasis is endemic in rural areas of Ghana. The goal of this study was to determine if there is a potential of establishing urban transmission cycles in Ghana's major cities. We clinically and immunologically assessed 625 individuals from the three major urban areas (Bawku, Bolgatanga and Secondi/Takoradi), finding that the prevalence of infection with Wuchereria bancrofti ranged from 0 to 12.5%. The results of a polymerase chain reaction based analysis of mosquitoes collected from these areas suggested that there is a low but detectable prevalence of mosquitoes infected with W. bancrofti. We conclude that there may be a potential for an established urban transmission of lymphatic filariasis in Ghana. © 2005 Blackwell Publishing Ltd.
Malaria vector studies in two ecological zones in southern Ghana.
(African Entomology, 2001) Appawu, M.A.; Baffoe-Wilmot, A.; Afari, E.A.; Dunyo, S.; Koram, K.A.; Nkrumah, F.K.
A two-year longitudinal malaria vector study was carried out in two communities, Dodowa and Prampram, located in the coastal forest and coastal savannah zones, respectively, of the Dangme West district of Ghana. Anopheles gambiae s.l. Giles was most prevalent in both study areas, followed by An. funestus Giles in Dodowa and An. pharoensis Theobald in Prampram. Anopheles gambiae s.s. occurred in sympatry with An. melas Theobald in Prampram. Small numbers of An. nili Theobald, An. hancocki Edwards, An. coustani Laveran, An. moucheti Evans and An. hargreavesi Evans were collected in Dodowa and their role in transmission was negligible. Anopheles gambiae s.l. and An. funestus were found to be the major human-biting species in Dodowa, while An. gambiae s.l. and An. pharoensis were the most common biting mosquitoes in Prampram. The overall biting rate of the anophelines at Dodowa was twice that at Prampram. Anopheles gambiae s.l. and An. funestus were identified as the main vectors of malaria by salivary gland dissections. Overall mean infectivity rate of both species was approximately 2.5 times higher at Dodowa than at Prampram. Anopheles pharoensis was not found to be infected with Plasmodium parasites. The intensity of malaria transmission at Dodowa, the coastal forest area, was about six times higher than Prampram, the coastal savanna area. Some aspects of control strategies are discussed.
Observations on parasites and Bacteria in stools of Children with diarrhoeal Disease
(Ghana Medical Journal, 1987-12) Anteson, R.K.; Minakami, K.; Mensah, P.P.A.; Appawu, M.A.
Studies involving the insolation of parasitic and bacterial agents in faecal samples of 363 children (age 3 months- 15 years) with diarrhoeal disease in Accra revealed a 39.4 % incidence rate of both parasitic anti bacteria. Helminthic and protozoan parasites accounted for 33.1% of the isolations. All the bacteria isolated. are known Causative diarrhoeal agents in children in Accra. Two enteral protozoa and 3 helminths known to cause diarrhoea in humans were found in this study and these were encountered alone or in various combinations in about 82.5 % of the positive stools. Concurrent isolation of parasitic and bacterial diarrhoeal agents was made in 5.6 % of the positive stools. It is suggested that helminths and or protozoa may play a major role in the causation of diarrhoea in children in Accra.
Potential factors influencing lymphatic filariasis transmission in “hotspot” and “control” areas in Ghana: the importance of vectors
(Infectious Diseases of Poverty, 2019-02) Pi-Bansa, S.; Osei, J.H.N.; Frempong, K.K.; Elhassan, E.; Akuoko, O.K.; Agyemang, D.; Ahorlu, C.; Appawu, M.A.; Koudou, B.G.; Wilson, M.D.; De Souza, D.K.; Dadzie, S.K.et.al
Background Mass drug administration (MDA) programmes for the control of lymphatic filariasis in Ghana, have been ongoing in some endemic districts for 16 years. The current study aimed to assess factors that govern the success of MDA programmes for breaking transmission of lymphatic filariasis in Ghana. Methods The study was undertaken in two “hotspot” districts (Ahanta West and Kassena Nankana West) and two control districts (Mpohor and Bongo) in Ghana. Mosquitoes were collected and identified using morphological and molecular tools. A proportion of the cibarial armatures of each species was examined. Dissections were performed on Anopheles gambiae for filarial worm detection. A questionnaire was administered to obtain information on MDA compliance and vector control activities. Data were compared between districts to determine factors that might explain persistent transmission of lymphatic filariasis. Results High numbers of mosquitoes were sampled in Ahanta West district compared to Mpohor district (F = 16.09, P = 0.002). There was no significant difference between the numbers of mosquitoes collected in Kassena Nankana West and Bongo districts (F = 2.16, P = 0.185). Mansonia species were predominant in Ahanta West district. An. coluzzii mosquitoes were prevalent in all districts. An. melas with infected and infective filarial worms was found only in Ahanta West district. No differences were found in cibarial teeth numbers and shape for mosquito species in the surveyed districts. Reported MDA coverage was high in all districts. The average use of bednet and indoor residual spraying was 82.4 and 66.2%, respectively. There was high compliance in the five preceding MDA rounds in Ahanta West and Kassena Nankana West districts, both considered hotspots of lymphatic filariasis transmission. Conclusions The study on persistent transmission of lymphatic filariasis in the two areas in Ghana present information that shows the importance of local understanding of factors affecting control and elimination of lymphatic filariasis. Unlike Kassena Nankana West district where transmission dynamics could be explained by initial infection prevalence and low vector densities, ongoing lymphatic filariasis transmission in Ahanta West district might be explained by high biting rates of An. gambiae and initial infection prevalence, coupled with high densities of An. melas and Mansonia vector species that have low or no teeth and exhibiting limitation. Electronic supplementary material The online version of this article (10.1186/s40249-019-0520-1) contains supplementary material, which is available to authorized users.
Role of species composition in malaria transmission by the Anopheles funestus group (Diptera: Culicidae) in Ghana
(Journal of Vector Ecology, 2013-06) Dadzie, S.K.; Brenyah, R.; Appawu, M.A.
Malaria remains a public health problem in Ghana, with Anopheles gambiae and Anopheles funestus as the predominant vectors. While much information exists on the species composition of An. gambiae, very little exists for An. funestus. This study was carried out to determine the species composition of An. funestus Giles populations from three ecological areas in Ghana and investigate their role in malaria transmission. Mosquitoes were collected using human landing and pyrethrum spray methods. A total of 10,254 Anopheles individuals were collected, out of which An. funestus constituted 53.6% (5,496). An. funestus sensu stricto (s.s.) and Anopheles lessoni were identified as the only members of the An. funestus group in all three ecological areas. All 62 sporozoite positive specimens that were identified as An. funestus s.s. were highly anthropophilic with a human blood index in the range of 80-96%, whereas more than 83% of the An. leesoni had fed on either bovine, goat, or sheep. Malaria transmission was higher in the Sahel savannah area than the rest of the ecological zones, with An. funestus s.s. being implicated as a vector of malaria in all ecological zones. Anopheles leesoni occurred in all the ecological areas but played no role in malaria transmission. The study established the importance of An. funestus s.s. in malaria transmission in Ghana. © 2013 The Society for Vector Ecology.
Species composition and inversion polymorphism of the anopheles gambiae complex in some sites of Ghana, West Africa.
(Acta Tropica, 1994) Appawu, M.A.; Baffoe-Wilmot, A.; Afari, E.A.; Nkrumah, F.K.; Petrarca, V.
Samples of Anopheles gambiae s.1. were collected from eight localities belonging to four of the five main ecological strata of Ghana. Analysis of ovarian polytene chromosomes revealed the presence of A. gambiae s.s. in all the sites studied, while A. arabiensis was detected only in the extreme northern locality of Navrongo and A. melas in some southern sites. Anopheles arabiensis showed a degree of inversion polymorphism comparable to the one observed in other West African countries. The analysis of the chromosomal polymorphism of A. gambiae s.s. showed the presence of the FOREST form in the rain forest localities and the SAVANNA form in the coastal savanna sites. The MOPTI form occurred sympatrically with the SAVANNA form in the northernmost locality. The possible influence of the presence of various taxa of the A. gambiae complex and of their intra-specific variants on malaria vectorial system is discussed.
Studies on the feeding behaviour of larvae of the predaceous mosquito culex (LUTZIA) tigripes grandpre and chamoy (üIPTERA: CULICIDAE)
(Insect Science and its Application, 2000-12) Appawu, M.A.; Dadzie, S.K.; Quartey, S.Q.
Experiments were carried out to determine the factors that influence the feeding behaviour of Cnkx tigripes, a mosquito whose larvae are predators of other mosquito larvae. The results indicated that the efficiency of predatory activities of Cx tigripes larvae increased as they developed from 1st to 4th instar with regard to the number of mosquito prey larvae they consumed in a given period of time. Fourth instars of Cx tigripes are the most voracious of all the stages and are better adapted for catching and consuming all stages of mosquito larvae. The mean number of mosquito larvae consumed in 24 hours increased with increasing prey density. When offered a mixture of different prey species and larval stages, Cx tigripes larvae consistently selected 4th instars of mosquitoes over pupae and preferred Acdes negypti larvae to the larvae of Cx qiiinquefasciatns and Anopheles gambiae. Prey size, density and mobility were also found to influence prey selection by Cx tigripes. ©2000ICIPE.
Susceptibility status of anopheles gambiae sensu stricto (diptera: Culicidae) to pyrethroid and carbamate insecticides in the greater accra region of Ghana, west africa.
(2009-09-01) Adeniran, T.T.; Brown, C.A.; Rogers, W.; Wilson, M.D.; Appawu, M.A.; Boakye, D.A.
Pyrethroids are the insecticides of choice for the treatment of bednets for malaria control. Pyrethroid resistance in Anopheles spp. vectors may adversely impact malaria control measures, and therefore it is important to know the initial level of pyrethroid resistance before pyrethroid-treated bednets are introduced. Furthermore, a search for replacement insecticides is necessary to manage any eventual high-resistance levels to pyrethroid insecticides that may affect the effectiveness of treated bednets. This study reports on the susceptibility of Anopheles gambiae s.s. exposed for 1 h to the pyrethroid insecticide permethrin and the carbamate insecticide propoxur, at eight localities in the Greater Accra region of Ghana. The observed mortality rates ranged between 21–92% and 92–100% to permethrin and propoxur, respectively. The results also showed a reduction in the knockdown time (KD50 and KD95) in propoxur (mean KD50 = 20 min and mean KD95 = 31 min) when compared with permethrin (mean KD50 = 47 min and mean KD95 = 87 min). The results suggest that permethrin may not be effective in all areas. Where pyrethroid resistance is a problem, propoxur could be an alternative for indoor residual spraying and for insecticide-treated materials such as curtains and eave screens.