Browsing by Author "Lawson, B.W."
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Item The epidemiology of lymphatic filariasis in Ghana, explained by the possible existence of two strains of Wuchereria bancrofti(Pan African Medical Journal, 2014) de Souza, D.K.; Osei-Poku, J.; Blum, J.; Baidoo, H.; Brown, C.A.; Lawson, B.W.; Wilson, M.D.; Bockarie, M.J.; Boakye, D.A.Lymphatic filariasis is a debilitating disease caused by the filarial worm Wuchereria bancrofti. It is earmarked for elimination by the year 2020 through the Global Program for the Elimination of LF (GPELF). In Ghana, mass treatment has been on-going since the year 2000. Earlier studies have revealed differing epidemiology of LF in the North and South of Ghana. This study was therefore aimed at understanding the possible impacts of W. bancrofti diversity on the epidemiology and control of LF in Ghana. Methods: The Mitochondrial, Cytochrome C Oxidase I gene of W. bancrofti samples was sequenced and analyzed. The test sequences were grouped into infrapopulations, and pairwise differences (Π) and mutation rates (θ) were computed. The amount of variance within and among populations was also computed using the AMOVA. The evolutionary history was inferred using the Maximum Parsimony method. Results: Seven samples from the South and 15 samples from the North were sequenced, and submitted to GenBank with accession numbers GQ479497- GQ479518. The results revealed higher mutation frequencies in the southern population, compared to the northern population. Haplotype analyses revealed a total of 11 haplotypes (Hap) in all the 22 DNA sequences, with high genetic variation and polymorphisms within the southern samples. Conclusion: This study showed that there is considerable genetic variability within W. bancrofti populations in Ghana, differences that might explain the observed epidemiology of LF. Further studies are however required for an in-depth understanding of LF epidemiology and control. © Dziedzom Komi de Souza et al.Item Reactive case detection of Plasmodium falciparum in western Kenya highlands: effective in identifying additional cases, yet limited effect on transmission(Malaria Journal, 2018-03) Aidoo, E.K.; Afrane, Y.A.; Machani, M.G.; Chebore, W.; Lawson, B.W.; Atieli, H.; Kariuki, S.; Lee, M.C.; Koepfli, C.; Zhou, G.; Githeko, A.K.; Yan, G.Background Identifying asymptomatic reservoirs of malaria parasites using index cases as entry points into the community is potentially a cost-effective way towards achieving malaria elimination. Methods Within 1 year, 1430 confirmed malaria cases were identified in Marani hospital, western Kenya. Fifty cases were followed up, and 108 index case household members and 612 neighbours within a 100 m radius were screened. As controls, samples were collected from 510 individuals matched with index cases and located at a distance of ≥ 500 m from them. Infections were diagnosed by microscopy and PCR while simultaneously collecting malaria vectors indoor using pyrethrum spray catches. Results In the index case and neighbour households, the prevalence of infection was approximately twice as high as in control households (by PCR: index cases households: 28.9%, neighbours: 25.3%, matched controls: 12.9%). In index case households, the indoor vector density (Anopheles gambiae and Anopheles funestus) was higher (0.46 female/house/night) than in neighbouring (0.31 f/h/n) and control houses (0.29 f/h/n). Conclusions Screening index case households and neighbours approximately doubles the chance to detect asymptomatic infections compared to randomly selected households. However, even if all cases were followed up, only a small proportion (˂ 10%) of the asymptomatic reservoir in the population would have been identified. Control programmes need to weigh the increased chance to find cases around index cases vs. the logistical challenges to target this subgroup within the population.