Doucouré K, Bissan Y, Back C, Hougard J M, Agoua H, Guillet P, Konaré M, Quillévéré D
OMS/OCP Bamako, Mali.
Ann Soc Belg Med Trop. 1994 Jun;74(2):113-27.
As part of the return of savanna migrants installed since a long time in forest regions, in the south of Sierra Leone, we carried out an experimental study about a cross-transmission between Simulium sirbanum from Missira (West-Mali) and the forest strain of Onchocerca volvulus in the south-west of Sierra Leone. This study will allow to know if there is a risk of onchocerciasis transmission recrudescence in relation to the reinstallation of these migrants in their native region. Because of the very high limitation to the forest strain of O. volvulus microfilariae output of the peritrophic membrane reduction with savanna black-flies and according to the very low mature parasite out put of S. sirbanum with this strain observed along this experimentation, the forest strain of O. volvulus from the south Sierra Leone appears maladjusted to S. sirbanum, the main vector of onchocerciasis in savanna regions. This observation implicates a very low intensity of transmission for this forest strain by savanna onchocerciasis vectors. The return of savanna migrants in their native region, installed in the south Sierra Leone since several decades, could not be, in a short time, an origin of onchocerciasis recrudescence in savanna regions of the Onchocerciasis Control Programme area cleaned by an effective vector control carried out since 1975 sustained now by a chemotherapeutic treatment reducing the human parasite reservoir. However, the preservation of this acquired necessitates an epidemiological supervision increased, because the interactions between the vector and the parasite for a long time could carry away a mutual adaptation and a sickness recrudescence.
作为长期定居在森林地区的稀树草原移民回迁的一部分，在塞拉利昂南部，我们针对来自米西拉（西非马里）的锡尔巴蚋与塞拉利昂西南部盘尾丝虫森林株之间的交叉传播开展了一项实验研究。这项研究将有助于了解，鉴于这些移民回迁到其原生地区，盘尾丝虫病传播是否有复发风险。由于稀树草原黑蝇导致围食膜减少对盘尾丝虫森林株微丝蚴产出有极大限制，且根据本实验观察到锡尔巴蚋对该株成熟寄生虫产出极低，塞拉利昂南部的盘尾丝虫森林株似乎不适于稀树草原地区盘尾丝虫病主要传播媒介锡尔巴蚋。这一观察结果表明，稀树草原盘尾丝虫病传播媒介对该森林株的传播强度极低。几十年来一直定居在塞拉利昂南部的稀树草原移民回迁，在短期内不太可能成为盘尾丝虫病控制项目区域稀树草原地区盘尾丝虫病复发的源头，该区域自1975年以来一直实施有效的病媒控制，目前通过化疗减少人体寄生虫宿主来维持。然而，要保持这种成果需要加强流行病学监测，因为长期以来病媒与寄生虫之间的相互作用可能导致相互适应和疾病复发。
