Bissan Y, Hougard J M, Doucouré K, Akpoboua A, Back C, Poudiougo P, Sib A P, Coulibaly Y, Guillet P, Sesay I
OMS/OCP, Programme ONCHO, Bamako, Mali.
Ann Trop Med Parasitol. 1995 Feb;89(1):63-72. doi: 10.1080/00034983.1995.11812930.
The major vectors of the blinding form of human onchocerciasis in West Africa are two blackfly species, Simulium sirbanum and Simulium damnosum s.s. (Diptera: Simuliidae), identified at the adult stage as the 'savanna group' of the Simulium damnosum complex. In 1988, in the central part of Sierra Leone, the average daily biting rate (females/man/day) by savanna blackflies (mostly S. sirbanum) during the peak of the dry season (April-May) was 59.9, making up 69.1% of total captures on average. There was evidence of a strong long-range immigration of adult females of S. sirbanum through eastern Guinea in the dry season, with a reverse movement towards Guinea in the rainy season. Therefore, in 1989, the World Health Organization's Onchocerciasis Control Programme (OCP) extended its vector control operations from central West Africa to rivers of central and northern Sierra Leone, and to rivers of eastern Guinea. Four years of efficient larviciding drastically reduced adult populations of S. sirbanum in Sierra Leone. In the peak of the dry seasons of 1993 and 1994, the average biting rate by savanna blackflies in central Sierra Leone had dropped to 1.0, making up only 4.3% of total captures on average. Yearly biting rates by S. sirbanum in central Sierra Leone were therefore reduced to 2% of their pre-intervention levels. Based on larval samples, the S. sirbanum has been replaced by two forest species, S. leonense in the south and S. squamosum in the north. Since 1992, it has been possible to calculate accurate transmission rates for blinding onchocerciasis, based on DNA-probe identifications. From 1993, the risk of transmission has not only been reduced by vector control but also by mass distribution of ivermectin to rural communities. In terms of control strategy, the authors conclude that larviciding operations could be alleviated in central Sierra Leone without increasing the risk of blinding onchocerciasis transmission, as long as the migration of S. sirbanum through eastern Guinea and northern Sierra Leone is prevented.
在西非，致盲型人类盘尾丝虫病的主要病媒是两种蚋类，即锡尔巴蚋和指名蚋（双翅目：蚋科），成虫阶段被确定为指名蚋复合体的“稀树草原类群”。1988年，在塞拉利昂中部，旱季（4月至5月）高峰期稀树草原蚋（主要是锡尔巴蚋）的平均每日叮咬率（雌蚋/人/天）为59.9，平均占总捕获量的69.1%。有证据表明，旱季时锡尔巴蚋成年雌蚋从几内亚东部有大量远距离迁入，雨季时则向几内亚反向移动。因此，1989年，世界卫生组织的盘尾丝虫病控制规划（OCP）将其病媒控制行动从西非中部扩展到塞拉利昂中部和北部的河流，以及几内亚东部的河流。四年有效的杀幼虫措施大幅减少了塞拉利昂锡尔巴蚋的成虫数量。在1993年和1994年旱季高峰期，塞拉利昂中部稀树草原蚋的平均叮咬率降至1.0，平均仅占总捕获量的4.3%。因此，塞拉利昂中部锡尔巴蚋的年叮咬率降至干预前水平的2%。根据幼虫样本，锡尔巴蚋已被两种森林蚋类取代，南部是莱昂蚋，北部是鳞状蚋。自1992年以来，基于DNA探针鉴定，可以计算出致盲型盘尾丝虫病的准确传播率。从1993年起，传播风险不仅通过病媒控制得以降低，还通过向农村社区大规模分发伊维菌素得以降低。在控制策略方面，作者得出结论，只要阻止锡尔巴蚋通过几内亚东部和塞拉利昂北部的迁移，在塞拉利昂中部可以减轻杀幼虫行动，而不会增加致盲型盘尾丝虫病传播的风险。
