Abong Raphael Awah, Ekanya Relindis, Nji Theobald Mue, Fombad Fanny Fri, Amambo Glory N, Ngong Innocentia, Nietcho Franck Noel, Deribe Kebede, Biholong Benjamin, Njiokou Flobert, Ekobo Same, Wondji Charles, Enyong Peter, Wanji Samuel
Department of Medical Laboratory Sciences, Faculty of Health Sciences, University of Buea, P.O. Box 63, Buea, Cameroon.
Research Foundation in Tropical Diseases and Environment, Buea, P.O. Box 474, Buea, Cameroon.
Parasit Vectors. 2025 Jul 1;18(1):242. doi: 10.1186/s13071-025-06837-5.
Despite over 18 years of annual ivermectin mass drug administration (MDA) in Cameroon's Nkam-Wouri River drainage, onchocerciasis transmission persists. Several reasons, including multiple breeding sites and abundant vector populations, contribute to ongoing transmission. High vector abundance also causes a biting nuisance to local populations. The change in paradigm from onchocerciasis control to elimination may not be achieved if alternative control measures are not used. There is a need to complement ivermectin MDA with other strategies. This study tested the susceptibility of Simulium larvae to temephos insecticide and monitored the effect of 10 weeks of ground larviciding on the larval density and black fly population.
Simulium breeding sites along the course of three rivers within the Solle transmission zone in the Nkam-Wouri River drainage were identified. Seven temephos concentrations (0.001-0.1 mg/l) were tested on freshly collected Simulium larvae for susceptibility. Simulium biting rates were monitored using human landing catches before and during 10 weeks of ground larviciding. Fishing was used to assess the abundance and diversity of large aquatic fauna, while the presence and diversity of small invertebrate fauna were assessed during the collection of larvae, as they are usually found on the same substrates in the river. Ground larviciding was conducted using the spraying method at two dosing points.
Six breeding sites were identified. Larval mortality decreased with temephos concentration, with 100% mortality observed at 0.1-0.025 mg/l. The non-target fauna included various fish species, crabs, crayfish, and small invertebrates. Ground larviciding cleared larvae from identified substrates and reduced adult fly biting rates by 82.8% (from 900 flies/man/day at the beginning to 180 flies/man/day at the end), a statistically significant decrease (χ = 1351.5, P < 0.001).
Simulium larvae showed susceptibility to temephos. Clearance of larvae from traps and identified natural substrates, and a significant reduction in the Simulium biting rates were observed.
尽管喀麦隆恩康-武里河流域每年进行超过18年的伊维菌素群体服药（MDA），盘尾丝虫病传播仍在持续。包括多个繁殖地和大量病媒种群在内的几个原因导致了传播的持续。高病媒密度也给当地居民带来叮咬困扰。如果不采用替代控制措施，从盘尾丝虫病控制到消除的范式转变可能无法实现。需要用其他策略补充伊维菌素MDA。本研究测试了蚋幼虫对杀螟硫磷杀虫剂的敏感性，并监测了10周地面杀幼虫对幼虫密度和蚋种群的影响。
在恩康-武里河流域索勒传播区的三条河流沿线确定了蚋繁殖地。对新鲜采集的蚋幼虫测试了七种杀螟硫磷浓度（0.001-0.1毫克/升）的敏感性。在10周地面杀幼虫之前和期间，使用人饵诱捕法监测蚋叮咬率。捕鱼用于评估大型水生动物的丰度和多样性，而小型无脊椎动物的存在和多样性在收集幼虫期间进行评估，因为它们通常在河流中的相同基质上被发现。在两个给药点使用喷雾法进行地面杀幼虫。
确定了六个繁殖地。幼虫死亡率随杀螟硫磷浓度降低，在0.1-0.025毫克/升时观察到100%死亡率。非目标动物包括各种鱼类、螃蟹、小龙虾和小型无脊椎动物。地面杀幼虫清除了已确定基质上的幼虫，并使成年蚋叮咬率降低了82.8%（从开始时的900只蚋/人/天降至结束时的180只蚋/人/天），差异有统计学意义（χ=1351.5, P<0.001）。
蚋幼虫对杀螟硫磷敏感。观察到诱捕器和已确定的天然基质上的幼虫被清除，并且蚋叮咬率显著降低。
