Saladin B, Saladin K, Holzer B, Dennis E, Hanson A, Degrémont A
Acta Trop. 1983 Sep;40(3):271-95.
In an area of high transmission of Schistosoma haematobium and S. mansoni in Central Liberia, populations of five villages and intermediate host snails were surveyed for two years. In three of these villages focal application of molluscicide (niclosamide) in the main transmission sites was combined with mass chemotherapy of a target population representing 76 to 90% of the contamination index. In the two other villages, which served as control, the prevalence indexes remained stable or increased a little during the period of this study. A three dose metrifonate mass treatment was applied in one village with only S. haematobium infections. The compliance was very poor for the second and third dose but the quantity of eggs eliminated by the whole population present before and after mass treatment was reduced by 50%. No snails were found after molluscicide applications but as the incidence remained unchanged it is suspected that inhabitants have been reinfected by going to their fields. Concurrent metrifonate and niridazole mass treatment in one dose was applied in another village with only S. haematobium infections. Molluscicide applications reduced the snail population by 80% but did not affect the transmission. Prevalence indexes were almost the same before and after this intervention. In the last village, praziquantel (40 mg/kg in 1 dose) was used because both S. haematobium and S. mansoni infections were present. Molluscicide applications reduced the snail population by 99% and 87% for Bulinus globosus and Biomphalaria pfeifferi, respectively. This intervention stopped the transmission of S. haematobium for at least one year and reduced the prevalence from 21% to 4.6%. On the contrary for S. mansoni infections, the incidence remained very high (50%) and the prevalence was unchanged after one year follow-up. This could be explained by lower efficacy of praziquantel against S. mansoni (cure rate: 53%) and of molluscicide application against B. pfeifferi, which are highly susceptible to S. mansoni (infection rate 44%). The importance of migration in these villages is emphasized. Prevalence indexes were largely influenced by the arrival of newcomers who played a more important role in the maintenance of transmission after target mass chemotherapy than the infected persons excluded from this treatment. The costs per capita protected were 3.33 US $ for metrifonate, 1.53 for metrifonate and niridazole combined and 1.67 US$ for praziquantel. These figures do not include costs for parasitological examinations.(ABSTRACT TRUNCATED AT 400 WORDS)
在利比里亚中部埃及血吸虫和曼氏血吸虫高传播地区，对五个村庄的人群和中间宿主螺类进行了为期两年的调查。在其中三个村庄，在主要传播地点局部施用杀螺剂（氯硝柳胺），并对占污染指数76%至90%的目标人群进行群体化疗。在另外两个作为对照的村庄，在本研究期间，流行率指数保持稳定或略有上升。在一个仅存在埃及血吸虫感染的村庄进行了三剂次的敌百虫群体治疗。第二剂和第三剂的依从性很差，但群体治疗前后全体人群排出的虫卵数量减少了50%。施用杀螺剂后未发现螺类，但由于发病率未变，怀疑居民因下田劳作而再次感染。在另一个仅存在埃及血吸虫感染的村庄，进行了一剂次敌百虫和硝唑尼特的联合群体治疗。施用杀螺剂使螺类数量减少了80%，但未影响传播。此次干预前后流行率指数几乎相同。在最后一个村庄，由于同时存在埃及血吸虫和曼氏血吸虫感染，使用了吡喹酮（40毫克/千克，一剂次）。施用杀螺剂后，球拟钉螺和费氏双脐螺数量分别减少了99%和87%。此次干预至少在一年内阻断了埃及血吸虫的传播，流行率从21%降至4.6%。相反，对于曼氏血吸虫感染，发病率仍然很高（50%），一年随访后流行率未变。这可能是由于吡喹酮对曼氏血吸虫的疗效较低（治愈率：53%），以及杀螺剂对高度易感曼氏血吸虫的费氏双脐螺的施用效果不佳（感染率44%）。强调了这些村庄中人口迁移的重要性。流行率指数在很大程度上受到新迁入者的影响，在目标群体化疗后，新迁入者在维持传播方面比被排除在治疗之外的感染者发挥了更重要的作用。人均保护成本方面，敌百虫为3.33美元，敌百虫和硝唑尼特联合为1.53美元，吡喹酮为1.67美元。这些数字不包括寄生虫学检查的费用。（摘要截取自400字）
