Duke B O, Moore P J
Tropenmed Parasitol. 1976 Sep;27(3):297-313.
The background and strategy of a campaign to control the transmission of Schistosoma haematobium at the isolated crater-lake villages of Barombi Mbo and Barombi Kotto are outlined. A two-pronged attack was envisaged, using N-tritylmorpholine (Frescon) to control the snail host, and niridazole (Ambilhar) to control the parasite in man. The lake villages and their environs are described. Observations, relevant to control, are recorded on the biology of Bulinus rohlfsi and B. camerunensis. Snail populations were sampled by hand picking, and by the use of basket traps baited with dead leaves. Some experiments on the susceptibility of both snails to S. haematobium are described, together with observations on the strains of schistosome developing in monkeys exposed to cercariae from naturally-infected snails from the lakes. Frescon was applied through a tube to the bottom layers at the edge of the lakes, where the snails lived. Concentrations of 2 ppm down to 0.5 ppm N-tritylmorpholine proved necessary for adequate kills. Intervals of 6 weeks between treatments sufficed to control B. rohlfsi, but applications every 2 weeks were needed for B. camerunensis. The numbers of egg-masses, of snails, and of infective snails of both species were recorded before, during and after Frescon/Ambilhar control; and snail transmission rates and indices have been calculated. Control operations reduced transmission by R. rohlfsi to 2.4% of the pre-control level, or to below the detectable threshold. They were most effective at Mbo, where B. rohlfsi was the only intermediate host. At Kotto, despite excellent B. rohlfsi control, transmission of the residual infections in the human population by B. camerunensis persisted during control operations, until the intervals between Frescon applications were cut to 2 weeks.
本文概述了在巴龙比姆博和巴龙比科托孤立的火山口湖村庄开展控制埃及血吸虫传播运动的背景和策略。设想采取双管齐下的措施，使用N-三苯甲基吗啉（Frescon）控制螺蛳宿主，并使用硝唑咪（安比哈）控制人体寄生虫。文中描述了这些湖滨村庄及其周边环境。记录了与防治相关的关于罗氏泡螺和喀麦隆泡螺生物学特性的观察结果。螺蛳种群通过手工采摘和使用用枯叶作诱饵的篮式诱捕器进行采样。文中还描述了关于这两种螺蛳对埃及血吸虫易感性的一些实验，以及对暴露于来自湖泊自然感染螺蛳尾蚴的猴子体内发育的血吸虫菌株的观察结果。通过一根管子将Frescon施用于螺蛳栖息的湖岸边底层。事实证明，浓度低至0.5 ppm的N-三苯甲基吗啉达到2 ppm才足以实现有效杀灭。两次处理之间间隔6周足以控制罗氏泡螺，但喀麦隆泡螺则需要每2周施用一次。在进行Frescon/安比哈防治之前、期间和之后，记录了两种螺蛳的卵块数量、螺蛳数量和感染性螺蛳数量；并计算了螺蛳传播率和指数。防治行动将罗氏泡螺的传播率降低到防治前水平的2.4%，或降至可检测阈值以下。这些行动在姆博最为有效，在那里罗氏泡螺是唯一的中间宿主。在科托，尽管对罗氏泡螺的防治效果极佳，但在防治行动期间，喀麦隆泡螺在人群中持续传播残余感染，直到将Frescon施用间隔缩短至2周。
