Morphometric diagnosis of Glossina palpalis (Diptera: Glossinidae) population structure in Ghana

Abstract Objective This study aimed to identify isolated population(s) of Glossina palpalis in Ghana using geometric morphometrics to evaluate variations in wing-shape and size between populations of the fly from three regions. Results Wing shape of G. palpalis tsetse flies from the Northern, Western and Eastern Regions varied significantly between each other. Populations from the Northern and Western Regions varied the most (Mahalanobis Distance = 54.20). The least variation was noticed between populations from the Western and Eastern Regions (MD = 1.99). On morphospace, the Northern population clearly separated from the Eastern and Western populations both of which overlapped. Wing centroid size also significantly varied among populations. Reclassification scores were satisfactory reaching 100% for the Northern population. The Northern population of G. palpalis is possibly isolated from the Western and Eastern Region populations. Meanwhile, a panmictic relationship could be on-going between the Western and Eastern populations. We speculate that geographical distance and subspecific difference between populations are among factors responsible for observed pattern of wing shape variations among the studied populations. The implications of results regarding choice of control strategy and limitations of the study are discussed

<it>Mansonia africana</it> and <it>Mansonia uniformis</it> are Vectors in the transmission of <it>Wuchereria bancrofti</it> lymphatic filariasis in Ghana

<p>Abstract</p> <p>Background</p> <p>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 <it>Anopheles melas</it>, <it>An. gambiae</it> s.s., <it>Mansonia</it> and <it>Culex</it> species are the main biting mosquitoes. <it>Anopheles gambiae</it> s.l. and <it>An. funestus</it> are the known vectors in Ghana and a recent report indicated that <it>An. melas</it> could transmit at low level microfilaraemia. However, because <it>An. melas</it> 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.</p> <p>Methods</p> <p>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 <it>W. bancrofti</it>. 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 <it>W. bancrofti</it> parasites found were confirmed using an established PCR method.</p> <p>Results</p> <p>A total of 825 indoor resting mosquitoes comprising of 501 <it>Anopheles</it> species, 239 <it>Mansonia</it> species, 84 <it>Culex</it> species and 1 <it>Aedes</it> species were dissected and examined for the presence of <it>W. bancrofti</it>. <it>Mansonia africana</it> had infection and infectivity rates of 2.5<it>%</it>. and 2.1% respectively. <it>Anopheles gambiae</it> s.l. had an infection rate of 0.4% and a similar infectivity rate. None of the <it>Culex</it> sp. and <it>Aedes</it> sp were found with infection. From the stored mosquitoes the infection and infectivity rates for <it>M. africana</it> were 7.6% (N = 144) and 2.8% respectively whilst the corresponding rates for <it>M. uniformis</it> were 2.9% (N = 244) and 0.8%.</p> <p>Conclusions</p> <p>This is the first report of <it>Mansonia</it> 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.</p