Abstract
Knowledge about transmission of sleeping sickness in a given focus is of a great importance since it governs the efficacy and the cost-effectiveness of control strategy. The Komo-Mondah focus is the most endemic sleeping sickness focus of Gabon. This focus has hardly been investigated and available publications are more than thirty years old. In order to update transmission features of sleeping sickness in that focus, we have conducted epidemiological and entomological surveys in March-April 2008. Epidemiological investigation relied on a case-control study using a quantitative and qualitative methodology (a structured questionnaire). Cases were affected people (parasitological positive) diagnosed by the national control program from 2004 to 2007, controls were those found disease-free after clinical examination and biological tests in the same period. They were asked to respond to a standard questionnaire concerning their activities after having signed a written consent. An unvaried analysis was first performed and then a multivariate analysis using the conditional logistic regression for matching method. Traps were then set out for four days in areas where people were working. Tsetse flies captured were identified and dissected; their density and human-fly contact points were determined. A risk of infection was associated with fishing activities (Odds-ratio: 5.69; CI95%: 3.38-9.57). Three species of Glossina were captured: Glossina palpalis palpalis, Glossina fuscipes fuscipes and G. Caliginea. Human-fly contact points were mainly landing stages. A combined strategy of case-detection and vector control targeted at landing stages should be efficient against the disease.
Highlights
Knowledge about transmission of sleeping sickness in a given focus is of a great importance since it governs the efficacy and the cost-effectiveness of control strategy
Rising and/or higher incidence of human African trypanosomiasis (HAT) in a given community relative to others have been linked to more intense human-fly contact, which can be a consequence of several factors: a higher density of the tsetse fly population, a spatial distribution which brings the flies closer to humans due to ecological changes, absence of alternative animal food sources resulting in tsetse taking a higher proportion of blood meals in humans, or humans spending more time in areas with denser tsetse populations [2]
We firstly reviewed records of the national control program; relevant demographic data of HAT patients diagnosed during the concerned period were collected, only patient positive for HAT were included in the study
Summary
Cases were affected people (parasitological positive) diagnosed by the national control program from 2004 to 2007, controls were those found disease-free after clinical examination and biological tests in the same period They were asked to respond to a standard questionnaire concerning their activities after having signed a written consent. The epidemiology of human African trypanosomiasis (HAT) call sleeping sickness due to Trypanosoma brucei gambiense has, for a long time, been thought to be determined essentially by human-fly contact and infection rates in the tsetse fly vector [1]. Humans are exposed to the disease as far as it is in the vicinity of tsetse-infested areas Various human activities such as fishing, farming, hunting, herding or water-related activities are known to be risk factors for acquiring sleeping sickness [3].
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