Browsing by Author "Appawu, M."

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Bio-efficacy, user perception and acceptability of pyrethroid based mosquito coils in controlling Anopheles gambiae s.l., in some parts of Accra, Ghana
(Japanese Journal of Medical Entomology and Zoology. Vol. 65 No. 3p. 139-145, 2014) Adu-Acheampong, S.; Kyerematen, R.; Dadzie, S.; Appawu, M.; Boakye, D.; Williams, J.
This study was to provide baseline information on patterns of coil usage, user acceptability and susceptibility levels of mosquito coils in some parts of Accra, Ghana. Three hundred and twenty questionnaires were administered to obtain information on knowledge and perception of respondents on the usage of mosquito coils. Adult Anopheles gambiae mosquitoes were tested for resistance to pyrethroid based mosquito coils using WHO standard protocol for testing household insecticide products. A total of 152 out of 320 respondents were direct users of coils. Close to 62% of this number frequently changes brands of coil they use. Over 61% of coil users indicated their willingness to continue to use coils even though there are adverse effects after use. Anopheles gambiae s.s. was the only species that was found in the study area. Mortalities of An. gambiae s.s. after exposure to coils were 37% for Angel®, 37.5% for Lord® and 15% for Heaven mosquito coil brands. More than half of the inhabitants in the area used coils to prevent mosquito bites. However, high levels of resistance was detected for all the three pyrethroid-based coils because West African kdr was detected in about 59% of samples of Anopheles gambiae s.s. that survived the exposure.
A community-wide study of malaria reduction: Evaluating efficacy and user-acceptance of a low-cost repellent in Northern Ghana
(American Journal of Tropical Medicine and Hygiene, 2013-02) Dadzie, S.; Boakye, D.; Asoala, V.; Koram, K.; Kiszewski, A.; Appawu, M.
NO MAS (NM) mosquito repellent was evaluated in two farming villages (4 km apart) in the Kassena Nankana district of northern Ghana. We determined its efficacy against local malaria vectors, degree of user acceptance, and its effect on malaria prevalence in households using insecticide-treated bed nets. The average protective efficacy of NM against Anopheles mosquitoes over 9 hours was 89.6%. Controls averaged 86 bites/person/night versus 9 bites/ person/night with the use of NM. Use of repellent was associated with a decrease of absolute malaria prevalence by 19.2% in the repellent village and by 6.5% in the control village (45.5 to 26.3, and 29.5 to 23.0, respectively). The user-acceptance rate of NM repellent was 96.1%. Ten percent (10%) of repellent users reported irritation as the main adverse effect during the period. Eighty-five percent (85%) of the users found the odor of NM appealing and 87% reported no inconvenience in applying the repellent daily. Copyright © 2013 by The American Society of Tropical Medicine and Hygiene.
A Comparative Study of Human Landing Catches and Pyrethrum Spray Catches Used in Malaria Vector Studies in the Kasena Nankana District (KND) of Ghana
(University of Ghana, 2003-09) Asoala, V.; Appawu, M.; Awumbila, B.; University of Ghana, College of Health Sciences, School of Public Health
The most direct and reliable method for estimating the man-biting rate is the human landing catches (HLC). It is considered the most representative and usually considered as the “Gold standard”, for determining human biting activity of mosquitoes. However, of recent there has been concerns about the ethics of using humans as baits to collect mosquitoes and therefore there is the need for an alternative method. This study compared Human Landing and Pyrethrum Spray methods in estimating malaria transmission intensity in an irrigated area in Kassena Nankana District of Northern Ghana. Both methods were used to collect mosquitoes during the wet and dry seasons of 2001-2002. Man biting rates, sporozoite rates and Entomological inoculation rates (EIR) were estimated for both methods. Using Human landing catches with a total of 192 man-nights of yielded 59.8% (6270) of Anopheles gambiae s.I., whereas Pyrethrum spray catches (PSC) contributed 40.2% (4220). Biting rates estimated from HLC during the wet season were significantly higher (P<0.05) than that of the dry season (60.9 versus 26.6), whereas, rates from PSC during the wet and dry seasons were not different (P>0.05). There were significant differences (P<0.05) between the biting rates obtained for Anopheles funestus for the two seasons using both methods. The overall sporozoite rate estimated using PSC, 7.1% (29/407) was significantly higher (P<0.05) than 4.9% (204/4353) for HLC. EIR per year using HLC was 123.9 and 1323.0 infective bites/ man/ year for the dry and wet seasons respectively while, it was 34.3 and 52.3 respectively using PSC. The annual EIR estimated for the two vectors, Anopheles gambiae and Anopheles funestus from HLC were similar (731 vrs 517.9) whilst that estimated from PSC was higher for Anopheles gambiae than Anopheles funestus (36.0 vrs 13.0). Although the estimated values using the two methods varied considerably, the transmission patterns were similar. In areas where mosquito numbers may be very low, for example, in the dry season, PSC may be useful in the assessment of malaria transmission intensity. The study provides information on the comparative use of HLC and PSC in vector transmission studies, which is necessary for the planning and implementation of future vector control strategies.
Discovery of Point Mutations in the Voltage-Gated Sodium Channel from African Aedes aegypti Populations: Potential Phylogenetic Reasons for Gene Introgression
(Public Library of Science, 2016) Kawada, H.; Higa, Y.; Futami, K.; Muranami, Y.; Kawashima, E.; Osei, J.H.N.; Sakyi, K.Y.; Dadzie, S.; de Souza, D.K.; Appawu, M.; Ohta, N.; Suzuki, T.; Minakawa, N.
Yellow fever is endemic in some countries in Africa, and Aedes aegpyti is one of the most important vectors implicated in the outbreak. The mapping of the nation-wide distribution and the detection of insecticide resistance of vector mosquitoes will provide the beneficial information for forecasting of dengue and yellow fever outbreaks and effective control measures. Methodology/Principal Findings: High resistance to DDT was observed in all mosquito colonies collected in Ghana. The resistance and the possible existence of resistance or tolerance to permethrin were suspected in some colonies. High frequencies of point mutations at the voltage-gated sodium channel (F1534C) and one heterozygote of the other mutation (V1016I) were detected, and this is the first detection on the African continent. The frequency of F1534C allele and the ratio of F1534C homozygotes in Ae. aegypti aegypti (Aaa) were significantly higher than those in Ae. aegypti formosus (Aaf). We could detect the two types of introns between exon 20 and 21, and the F1534C mutations were strongly linked with one type of intron, which was commonly found in South East Asian and South and Central American countries, suggesting the possibility that this mutation was introduced from other continents or convergently selected after the introgression of Aaa genes from the above area. Conclusions/Significance: The worldwide eradication programs in 1940s and 1950s might have caused high selection pressure on the mosquito populations and expanded the distribution of insecticide-resistant Ae. aegypti populations. Selection of the F1534C point mutation could be hypothesized to have taken place during this period. The selection of the resistant population of Ae. aegypti with the point mutation of F1534C, and the worldwide transportation of vector mosquitoes in accordance with human activity such as trading of used tires, might result in the widespread distribution of F1534C point mutation in tropical countries. © 2016 Kawada et al.
An Investigation into Impact of Unsprayed Surfaces on Mosquito Behaviour and Malaria Transmission in an Area Undergoing Indoor Residual Spraying In Northern Ghana.
(University of Ghana, 2014-07) Mante, O.A.; Appawu, M.; Dadzie, S.; Kyerematen, R.; University of Ghana, College of Basic and Applied Sciences, School of Biological Sciences, Department of Animal Biology and Conservation Science (DABCS)
Indoor Residual Spraying (IRS) is one of the malaria vector control tools used in the control of malaria and has helped to reduce malaria transmission in many areas in Sub-Saharan Africa. This involves spraying the walls of rooms with insecticides so as to kill any mosquito that rest on the insecticide treated walls after feeding. However, recent discussions have been centered on the role unsprayed surfaces such as hanging cloths play in sprayed rooms in malaria transmission. In this study, the effect of hanged clothes on mosquito resting and exiting behaviour as well as on malaria transmission was investigated using mosquitoes captured by pyrethrum spray (PSC) and window exit trap (ETC) collections. The study was undertaken in Tarikpaa, in the Savelugu-Nanton district in Northern Ghana, an area undergoing Indoor Residual Spraying. Kulaa in the Tamale district of Northern Ghana was used as the control area with no IRS. Mosquitoes were sampled from August to December 2013. Anopheles gambiae s.l., Anopheles funestus, Anopheles nili and Anopheles rufipes were the Anopheles species collected during the period of the study making up 97.1%, 2.0%, 0.3% and 0.6% of the species respectively. Both An. coluzzi (M form) and S molecular forms occurred in all rooms in both areas. An. gambiae s.l. collected in rooms with hanging clothes in the IRS community (Tarikpaa) was lower (14.68%) compared to rooms with no hanging clothing (85.32%). The same was observed for the non-IRS community (Kulaa). A total of 18 and 100 Anopheles mosquitoes were collected from rooms with hanging clothes and rooms without hanging clothes in Tarikpaa respectively. The mean Indoor Resting Density (IRD) of Anopheles collected from rooms in the IRS area without hanging clothes was higher than that of rooms with hanging clothes (2.7 mosquitoes/room vs 0.36 mosquitoes/room). However, this difference was not significant (F (1, 12) = 2.078, P = 0.175). The same trend was observed for the unsprayed community, Kulaa. A Fed to Gravid ratio of 0.9:1 and 1:1 was estimated for mosquitoes collected exiting rooms with hanging clothes and without hanging clothes respectively. The sporozoite rate for both rooms with hanging clothes and rooms without hanging clothes in Tarikpaa was zero. The only positive mosquito samples were from the rooms without hanging clothes in the non-sprayed area (1.83%). An Entomological Inoculation Rate (EIR) of 0.0043 infective bites/man/night was estimated for An. gambiae collected from Kulaa. The fed: gravid ratio also indicated that more blood fed mosquitoes left the rooms immediately after feeding in the presence of insecticide on the walls. The number of Anopheles species collected by ETC from rooms with hanging clothes in the IRS area was significantly higher than in rooms without hanging clothes. The practice of hanging clothes in the area undergoing indoor residual spraying did not affect malaria transmission. Anopheles mosquitoes tend to exit rooms in the morning after feeding. This has implications for the effectiveness of the IRS in the area because many of the mosquitoes will not rest on the insecticide treated walls to be killed.
Lymphatic filariasis on the coast of Ghana.
(Transactions of the Royal Society of Tropical Medicine and Hygiene, 1996) Dunyo, S.K.; Appawu, M.; Nkrumah, F.K.; Baffoe-Wilmot, A.; Pedersen, E.M.; Simonsen, P.E.
Parasitological, clinical and entomological surveys for lymphatic filariasis were carried out in 6 villages and 3 towns on the coast of Ghana. Few or no filarial infections were observed in the towns or in the villages east of Accra. However, Wuchereria bancrofti microfilaraemia was common in the 4 western villages, with overall prevalences of 9.2%–25.4% and overall microfilariae (mf) geometric mean intensities of 321–1172 mf/mL of blood. In the same villages, hydrocele affected 8.5%–27.9% of adult males (aged ⩾20 years), and 5.6%–6.6% of adult individuals had elephantiasis (mainly of the legs). In general, the patterns of filarial infection and disease in the endemic villages resembled those observed in endemic villages in the coastal part of East Africa, with the exception that in the Ghanaian focus more females than males were affected by elephantiasis. Entomological surveys revealed that Anopheles gambioe s.l. and A. funestus were vectors of filariasis in the endemic villages. Only negligible prevalences of microfilaraemia were observed in town communities located close to highly endemic villages. Control of filariasis in this area is difficult with presently available measures, and new control tools, especially development of new drug regimens for mass treatment, are greatly needed.
Malaria infection, morbidity and transmission in two ecological zones Southern Ghana
(1995-05) Afari, E.A.; Appawu, M.; Dunyo, S.; Baffoe-Wilmot, A.; Nkrumah, F.K.
A one year survey was conducted in 1992 to compare malaria infection, morbidity and transmission patterns between a coastal savannah community (Prampram) and a community (Dodowa) in the forest zone in southern Ghana. The study population of 6682 at Prampram and 6558 at Dodowa were followed up in their homes once every two weeks and all episodes of clinical malaria recorded. Blood films for microscopy were prepared from 600 participants randomly selected in each community in April and in August representing dry and wet seasons respectively. Mosquitoes biting humans between 1800 hrs and 0600 hrs, as well as indoor and outdoor resting mosquitoes were collected weekly. All mosquitoes collected were classified into species and examined for sporozoites by dissection and ELISA. The incidence rate of clinical malaria was higher in Dodowa (106.6/1000 pop.) than in Prampram (68.5/1000 pop.) It was highest in < 10 year age groups in both communities. It was also higher in the wet season than in the dry season. The prevalence of patent parasitaemia at Prampram and Dodowa in April in the dry season. The prevalence of patent parasitaemia at Prampram and Dodowa in April 1992 was 19.8% (117/590) and 42.2% (253/599) respectively. The corresponding figures for August were 26.6%(160/602)at Prampram and 51.3% (309/602) at Dodowa. Plasmodium falciparum infection contributed 78-85% of the parasitaemia in April and 93-99% in August. The average man-biting rate for Anopheles gambiae s.l was higher at Prampram than at Dodowa (1.54 vs 0.79 bites/man/night) but the average sporozoite rate was higher at Dodowa than at Prampram (2% vs 0.7%). The peak of biting density at Prampram occurred in June whilst that of Dodowa occurred in November.
Malaria transmission dynamics at a site in northern Ghana proposed for testing malaria vaccines.
(Tropical Medicine and International Health, 2004-01-01) Appawu, M.; Owusu-Agyei, S.; Dadzie, S.; Asoala, V.; Anto, F.; Koram, K.A.; Fryauff, D.J.
We studied the malaria transmission dynamics in Kassena Nankana district (KND), a site in northern Ghana proposed for testing malaria vaccines. Intensive mosquito sampling for 1 year using human landing catches in three micro-ecological sites (irrigated, lowland and rocky highland) yielded 18 228 mosquitoes. Anopheles gambiae s.l. and Anopheles funestus constituted 94.3% of the total collection with 76.8% captured from the irrigated communities. Other species collected but in relatively few numbers were Anopheles pharoensis (5.4%) and Anopheles rufipes (0.3%). Molecular analysis of 728 An. gambiae.s.l. identified Anopheles gambiae s.s. as the most dominant sibling species (97.7%) of the An. gambiae complex from the three ecological sites. Biting rates of the vectors (36.7 bites per man per night) were significantly higher (P < 0.05) in the irrigated area than in the non-irrigated lowland (5.2) and rocky highlands (5.9). Plasmodium falciparum sporozoite rates of 7.2% (295/4075) and 7.1% (269/3773) were estimated for An. gambiae s.s. and An. funestus, respectively. Transmission was highly seasonal, and the heaviest transmission occurred from June to October. The intensity of transmission was higher for people in the irrigated communities than the non-irrigated ones. An overall annual entomological inoculation rate (EIR) of 418 infective bites was estimated in KND. There were microecological variations in the EIRs, with values of 228 infective bites in the rocky highlands, 360 in the lowlands and 630 in the irrigated area. Approximately 60% of malaria transmission in KND occurred indoors during the second half of the night, peaking at daybreak between 04.00 and 06.00 hours. Vaccine trials could be conducted in this district, with timing dependent on the seasonal patterns and intensity of transmission taking into consideration the micro-geographical differences and vaccine trial objectives.
Mansonia africana and Mansonia uniformis are Vectors in the transmission of Wuchereria bancrofti lymphatic filariasis in Ghana
(2012-05-07) Ughasi, J.; Bekard, H.E.; Coulibaly, M.; Adabie-Gomez, D.; Gyapong, J.; Appawu, M.; Wilson, M.D.; Boakye, D.A.
AbstractBackgroundRecent data from Ghana indicates that after seven rounds of annual mass drug administration (MDA) there is still sustained transmission albeit at low levels in certain areas where Anopheles melas, An. gambiae s.s., Mansonia and Culex species are the main biting mosquitoes. Anopheles gambiae s.l. and An. funestus are the known vectors in Ghana and a recent report indicated that An. melas could transmit at low level microfilaraemia. However, because An. melas is not found everywhere there was the need to determine whether any of the other culicine species could also be playing a role in the transmission of LF.MethodsIndoor mosquitoes collected once a month for three months using pyrethrum spray catches in six communities within the Kommenda-Edina-Eguafo-Abirem (KEEA) District, Central Region of Ghana were morphologically identified, dissected and examined for the presence of W. bancrofti. Additionally, stored mosquito samples collected during previous years in 8 communities from the Gomoa District also in the Central Region were similarly processed. The identities of all W. bancrofti parasites found were confirmed using an established PCR method.ResultsA total of 825 indoor resting mosquitoes comprising of 501 Anopheles species, 239 Mansonia species, 84 Culex species and 1 Aedes species were dissected and examined for the presence of W. bancrofti. Mansonia africana had infection and infectivity rates of 2.5%. and 2.1% respectively. Anopheles gambiae s.l. had an infection rate of 0.4% and a similar infectivity rate. None of the Culex sp. and Aedes sp were found with infection. From the stored mosquitoes the infection and infectivity rates for M. africana were 7.6% (N = 144) and 2.8% respectively whilst the corresponding rates for M. uniformis were 2.9% (N = 244) and 0.8%.ConclusionsThis is the first report of Mansonia species as vectors of lymphatic filariasis (LF) in Ghana and in West Africa since that of 1958 in Guinea. The revelation of a hitherto unrecognised vector which is possibly more efficient in transmission than the recognised ones has a profound implication for elimination of lymphatic filariasis programmes in the sub-region.
Mansonia africana and Mansonia uniformis are Vectors in the transmission of Wuchereria bancrofti lymphatic filariasis in Ghana
(2012) Ughasi, J.; Bekard, H.E.; Coulibaly, M.; Adabie-Gomez, D.; Gyapong, J.; Appawu, M.; Wilson, M.D.; Boakye, D.A.
Background: Recent data from Ghana indicates that after seven rounds of annual mass drug administration (MDA) there is still sustained transmission albeit at low levels in certain areas where Anopheles melas, An. gambiae s.s., Mansonia and Culex species are the main biting mosquitoes. Anopheles gambiae s.l. and An. funestus are the known vectors in Ghana and a recent report indicated that An. melas could transmit at low level microfilaraemia. However, because An. melas is not found everywhere there was the need to determine whether any of the other culicine species could also be playing a role in the transmission of LF. Methods: Indoor mosquitoes collected once a month for three months using pyrethrum spray catches in six communities within the Kommenda-Edina-Eguafo-Abirem (KEEA) District, Central Region of Ghana were morphologically identified, dissected and examined for the presence of W. bancrofti. Additionally, stored mosquito samples collected during previous years in 8 communities from the Gomoa District also in the Central Region were similarly processed. The identities of all W. bancrofti parasites found were confirmed using an established PCR method. Results: A total of 825 indoor resting mosquitoes comprising of 501 Anopheles species, 239 Mansonia species, 84 Culex species and 1 Aedes species were dissected and examined for the presence of W. bancrofti. Mansonia africana had infection and infectivity rates of 2.5%. and 2.1% respectively. Anopheles gambiae s.l. had an infection rate of 0.4% and a similar infectivity rate. None of the Culex sp. and Aedes sp were found with infection. From the stored mosquitoes the infection and infectivity rates for M. africana were 7.6% (N = 144) and 2.8% respectively whilst the corresponding rates for M. uniformis were 2.9% (N = 244) and 0.8%. Conclusions: This is the first report of Mansonia species as vectors of lymphatic filariasis (LF) in Ghana and in West Africa since that of 1958 in Guinea. The revelation of a hitherto unrecognised vector which is possibly more efficient in transmission than the recognised ones has a profound implication for elimination of lymphatic filariasis programmes in the sub-region. © 2012 Ughasi et al.
Monitoring lymphatic filariasis interventions: Adult mosquito sampling, and improved PCR - based pool screening method for Wuchereria bancrofti infection in Anopheles mosquitoes
(2007-11-29) Boakye, D.A.; Baidoo, H.A.; Glah, E.; Brown, C.; Appawu, M.; Wilson, M.D.
Abstract Background Monitoring and evaluation are essential to the successful implementation of mass drug administration programmes for LF elimination. Monitoring transmission when it is low requires both large numbers of mosquito vectors and sensitive methods for detecting Wuchereria bancrofti infections in them. PCR-based methods are preferred over classical dissections but the best protocol so far achieved detection of one L3 Wuchereria bancrofti larva in a pool of 35–50 Anopheles mosquitoes. It also lacks consistency and remains still a costly tool. Hence we decided to improve upon this to achieve detection in a pool of 100 or more by enhancing the quality of the template DNA. Prior to this we also evaluated three vector sampling methods in the context of numbers for monitoring. Methods Human landing, pyrethrium spray and light traps catches were conducted concurrently at sites in an LF endemic district in Ghana and the numbers obtained compared. Two DNA extraction methods; Bender buffer and phenol/chloroform purification, and DNAeasy Tissue kit (Quaigen Inc) were used on pools of 25, 50, 75 100 and 150 mosquitoes each seeded with one L3 or its quivalent amount of DNA. Then another set of extracted DNA by the two methods was subjected to Dynal bead purification method (using capture oligonucleotide primers). These were used as template DNA in PCR to amplify W. bancrofti sequences. The best PCR result was then evaluated in the field at five sites by comparing its results (infections per 1000 mosquitoes) with that of dissection of roughly equal samples sizes. Results The largest numbers of mosquitoes were obtained with the human landing catches at all the sites sampled. Although PCR detection of one L3 in pools of 25, 50 and 75 mosquitoes was consistent irrespective of the extraction method, that of one L3 in 100 was only achieved with the kit-extracted DNA/Dynal bead purification method. Infections were found at only two sites by both dissection and pool-screening being 14.3 and 19 versus 13.4 and 20.1 per 1000 Anopheles mosquitoes respectively, which were not statistically significant Discussion and conclusion HLC still remains the best option for sampling for the large numbers of mosquitoes required for monitoring transmission during MDA programmes, when vector population densities are high and classical indices of transmission are required. One – in – 100 detection is an improvement on previous PCR pool-screening methods, which in our opinion was a result of the introduction of the extra step of parasite DNA capture using Dynal/beads. As pool sizes increase the insects DNA will swamp parasite DNA making the latter less available for an efficient PCR, therefore we propose either additional steps of parasite DNA capture or real-time PCR to improve further the pool screening method. The study also attests also to the applicability of Katholi et al's algorithm developed for determining onchocerciasis prevalence in LF studies.
Monitoring lymphatic filariasis interventions: Adult mosquito sampling, and improved PCR - based pool screening method for wuchereria bancrofti infection in anopheles mosquitoes.
(2007) Boakye, D.A.; Baidoo, H.A.; Glah, E.; Brown, C.; Appawu, M.; Wilson, M.D.
BACKGROUND: Monitoring and evaluation are essential to the successful implementation of mass drug administration programmes for LF elimination. Monitoring transmission when it is low requires both large numbers of mosquito vectors and sensitive methods for detecting Wuchereria bancrofti infections in them. PCR-based methods are preferred over classical dissections but the best protocol so far achieved detection of one L3 Wuchereria bancrofti larva in a pool of 35-50 Anopheles mosquitoes. It also lacks consistency and remains still a costly tool. Hence we decided to improve upon this to achieve detection in a pool of 100 or more by enhancing the quality of the template DNA. Prior to this we also evaluated three vector sampling methods in the context of numbers for monitoring. METHODS: Human landing, pyrethrium spray and light traps catches were conducted concurrently at sites in an LF endemic district in Ghana and the numbers obtained compared. Two DNA extraction methods; Bender buffer and phenol/chloroform purification, and DNAeasy Tissue kit (Quaigen Inc) were used on pools of 25, 50, 75 100 and 150 mosquitoes each seeded with one L3 or its quivalent amount of DNA. Then another set of extracted DNA by the two methods was subjected to Dynal bead purification method (using capture oligonucleotide primers). These were used as template DNA in PCR to amplify W. bancrofti sequences. The best PCR result was then evaluated in the field at five sites by comparing its results (infections per 1000 mosquitoes) with that of dissection of roughly equal samples sizes. RESULTS: The largest numbers of mosquitoes were obtained with the human landing catches at all the sites sampled. Although PCR detection of one L3 in pools of 25, 50 and 75 mosquitoes was consistent irrespective of the extraction method, that of one L3 in 100 was only achieved with the kit-extracted DNA/Dynal bead purification method. Infections were found at only two sites by both dissection and pool-screening being 14.3 and 19 versus 13.4 and 20.1 per 1000 Anopheles mosquitoes respectively, which were not statistically significant DISCUSSION AND CONCLUSION: HLC still remains the best option for sampling for the large numbers of mosquitoes required for monitoring transmission during MDA programmes, when vector population densities are high and classical indices of transmission are required. One - in - 100 detection is an improvement on previous PCR pool-screening methods, which in our opinion was a result of the introduction of the extra step of parasite DNA capture using Dynal/beads. As pool sizes increase the insects DNA will swamp parasite DNA making the latter less available for an efficient PCR, therefore we propose either additional steps of parasite DNA capture or real-time PCR to improve further the pool screening method. The study also attests also to the applicability of Katholi et al's algorithm developed for determining onchocerciasis prevalence in LF studies.
Patterns of household insecticide use and pyrethroid resistance in Anopheles gambiae sensu stricto (Diptera: Culicidae) within the Accra metropolis of Ghana
(African Entomology, 2009) Boakye, D.A.; Adasi, K.; Appawu, M.; Brown, C.A.; Wilson, M.D.
Risk of transmission of viral haemorrhagic fevers and the insecticide susceptibility status of aedes aegypti (linnaeus) in some sites in Accra, Ghana
(Ghana Medical Journal, 2016-09) Suzuki, T.; Osei, J.H.; Sasaki, A.; Adimazoya, M.; Appawu, M.; Boakye, D.; Ohta, N.; Dadzie, S.
Background: Dengue is one of the emerging diseases that can mostly only be controlled by vector control since there is no vaccine for the disease. Although, Dengue has not been reported in Ghana, movement of people from neighbouring countries where the disease has been reported can facilitate transmission of the disease. Objective: This study was carried on the University of Ghana campus to determine the risk of transmission of viral haemorrhagic fevers and the insecticide susceptibility status of Ae. aegypti in some sites in Accra, Ghana. Design: Larval surveys were carried to inspect containers within households and estimate larval indices and adult Aedes mosquitoes were collected using human landing collection technique. WHO tube assays was used to assess the insecticide susceptibility status of Aedes mosquitoes. Results: Ae. aegypti were the most prevalent species, 75.5% and followed by Ae. vittatus, 23.9 %. Ae. albopictus and Ae. granti were in smaller numbers. Household index (HI), Breteau index (BI), and container index were calculated as 8.2%, 11.2% and 10.3% respectively with man-vector contact rate of 0.67 bites/man-hour estimated for the area. The mortalities recorded for Ae. aegypti from WHO tube assays was 88%, 94%, 80% and 99% for DDT (4%), deltamethrin (0.05%), lambdacyhalothrin (0.05%) and permethrin (0.75%) respectively. Conclusion: The survey results indicated that the density of Aedes mosquitoes was considered to be sufficient to promote an outbreak of viral haemorrhagic fevers on Legon Campus. Aedes mosquitoes were found to be resistant to DDT, deltamethrin and lamdacyhalothrin, but susceptible to permethrin.
Serological evidence of vector and parasite exposure in Southern Ghana: the dynamics of malaria transmission intensity
(Parasites & Vectors, 2015-04) Badu, K.; Gyan, B.; Appawu, M.; Mensah, D.; Dodoo, D.; Yan, G.; Drakeley, C.; Zhou, G.; Owusu-Dabo, E.; Koram, K.A.
Background: Seroepidemiology provides robust estimates for tracking malaria transmission when intensity is low and useful when there is no baseline entomological data. Serological evidence of exposure to malaria vectors and parasite contribute to our understanding of the risk of pathogen transmission, and facilitates implementation of targeted interventions. Ab to Anopheles gambiae salivary peptide (gSG6-P1) and merozoite surface protein one (MSP-1 19) reflect human exposure to malaria vectors and parasites. This study estimated malaria transmission dynamics using serological evidence of vector and parasite exposure in southern Ghana. Methods: Total IgG responses to both antigens in an age stratified cohort (<5, 5 – 14, >14) were measured from South-eastern Ghana. 295 randomly selected sera were analyzed from archived samples belonging to a cohort study that were followed at 3 consecutive survey months (n = 885); February, May and August 2009. Temporal variations in seroprevalence of both antigens as well as differences between the age-stratified cohorts were determined by χ 2 test with p < 0.05 statistically significant. Non-parametric repeated ANOVA – Friedman ’ s test was used to test differences in antibody levels. Seroprevalence data were fitted to reversible catalytic model to estimate sero-conversion rates. Results: Whereas parasite prevalence was generally low 2.4%, 2.7% and 2.4% with no apparent trends with season, seroprevalence to both gSG6-P1 and MSP1 19 were high (59%, 50.9%, 52.2%) and 57.6%, 52.3% and 43.6% in respective order from Feb. to August. Repeated measures ANOVA showed differences in median antibody levels across surveys with specific significant differences bet ween February and May but not August by post hoc Dunn ’ s multiple comparison tests for gSG6-P1. For MSP1 19 , no differences were observed in antibody levels between February and May but a significant decline was observe d from May to August. Seroconversion rates for gSG6-P1 increased by 1.5 folds from February to August and 3 folds for MSP1 19 . Conclusion: Data suggests exposure to infectious bites may be declining whereas mosquito bites remains high. Sustained malaria control efforts and surveillance are needed to drive malaria further down and to prevent catastrophic rebound. Operational fac tors for scaling up have been discussed.
Short report: ITS-1 DNA sequence confirmation of leishmania major as a cause of cutaneous leishmaniasis from an outbreak focus in the Ho district, southeastern Ghana.
(2006) Fryauff, D.J.; Hanafi, H.A.; Klena, J.D.; Hoel, D.F.; Appawu, M.; Rogers, W.; Puplampu, N.; Odoom, S.; Kweku, M.; Koram, K.A.; Wilson, M.D.; Raczniak, G.; Boakye, D.
Species composition and risk of transmission of some Aedes-borne arboviruses in some sites in Northern Ghana
(PLOS, 2021) Joannides, J.; Dzodzomenyo, M.; Azerigyik, F.; Agbosu, E.E.; Pratt, D.; Osei, J.H.N.; Pwalia, R.; Amlalo, G.K.; Appawu, M.; Takashi, H.; Iwanaga, S.; Buchwald, A.; Rochford, R.; Boakye, D.; Koram, K.; Bonney, K.; Dadzie, S.
Aedes-borne viral diseases mainly Yellow Fever (YF), Dengue (DEN), Zika (ZIK) and Chi kungunya (CHK) have contributed to many deaths’ in the world especially in Africa. There have been major outbreaks of these diseases in West Africa. Although, YF outbreaks have occurred in Ghana over the years, no outbreak of DEN, ZIK and CHK has been recorded. However, the risk of outbreak is high due to its proximity to West African countries where outbreaks have been recently been recorded. This study surveyed the mosquito fauna to assess the risk of transmission of Yellow fever (YFV), Dengue (DENV), Chikungunya (CHKV) and Zika (ZIKV) viruses in Larabanga and Mole Game Reserve areas in Northern Ghana. The immature and adult stages of Aedes mosquitoes were collected from Larabanga and Mole Game Reserve area. There was a significant (P>0.001) number of mosquitoes collected during the rainy season than the dry season. A total of 1,930 Aedes mosquitoes were collected during the rainy season and morphologically identified. Of these, 1,915 (99.22%) were Aedes aegypti and 15 (0.22%) were Aedes vittatus. During the dry season, 27 Ae. aegypti mosquitoes were collected. A total of 415 Ae. aegypti mosquitoes were molecularly identified to subspecies level of which Ae. (Ae) aegypti aegypti was the predominant subspecies. Both Ae. aegypti aegypti and Ae aegypti formosus exist in sympatry in the area. All Aedes pools (75) were negative for DENV, ZIKV and CHKV when examined by RT- PCR. Three Larval indices namely House Index, HI (percentage of houses positive for Aedes larvae or pupae), Container Index, CI (the percentage of containers positive for Aedes larvae or pupae) and Breteau Index, BI (number of positive containers per 100 houses inspected) were assessed as a measure for risk of transmission in the study area. The HI, CI and BI for both sites were as follows; Mole Game Reserve (HI, 42.1%, CI, 23.5% and BI, 100 for rainy season and 0 for all indices for dry season) and Larabanga (39%, 15.5% and 61 for rainy season and 2.3%, 1.3% and 2.3 for dry season). The spatial distribution of Aedes breeding sites in both areas indicated that Aedes larvae were breeding in areas with close proximity to humans. Lorry tires were the main source of Aedes larvae in all the study areas. Information about the species composition and the potential role of Aedes mosquitoes in future outbreaks of the diseases that they transmit is needed to design efficient surveillance and vector control tools.
Surveillance of Viral Haemorrhagic Fevers in Ghana: Entomological Assessment of the Risk of Transmission in the Northern Regions
(Ghana Medical Journal, 2006-12) Appawu, M.; Dadzie, S.; Abdul, H.; Asmah, H.; Boakye, D.; Wilson, M.; Ofori-Adjei, D.
Objectives: To assess the risk of transmission of viral haemorrhagic fevers in northern Ghana. Design: A two-year cross-sectional entomological study was carried out in four communities in the northern part of Ghana. Standard WHO methods were used to collect adult and larvae of Aedes mosquitoes to estimate man-vector contact rates and larval indices. Results: A total of 2804 households were surveyed to estimate larval indices and man-vector contacts of potential vectors of viral haemorrhagic fevers such as Yellow fever and Dengue. Over 56% households in each study site were positive for Aedes larvae. Relatively higher Breteaux index (BI) and Container index (CI) were estimated in Damongo (BI: 180 and CI: 44.8) and Jirapa (BI: 149.7 and CI: 41.5) compared to Tumu (BI: 76.1 and CI: 19.5) and Bolgatanga (BI: 72.4 and CI: 20.6). Man-biting rates of 9.8 and 18.5 bites /man/hour were estimated for Damongo and Jirapa respectively whilst Bolgatanga recorded 10 B/M/H. Generally, man-vector contact rates in all the study sites were higher during the dry season than the wet season. Larval indices showed seasonal variations and the dry season was identified as the high-risk period for transmission of viral haemorrhagic fevers and possible disease outbreaks. No flavivirus was detected in the 2034 Aedes mosquitoes from the study sites by RTPCR. Conclusions: Aedes mosquito larval densities and adult biting rates, in all the study areas were sufficient to promote outbreaks of viral haemorrhagic fevers.