Olanrewaju Timothy O, Enwezor Felicia N C, Lar Luret A, Igbe Michael A, Abdullahi Ramatu A, Adeleke Monsuru A, Adekeye Oluwatosin B, Elhassan Elizabeth O
Nigerian Institute for Trypanosomiasis (and Onchocerciasis) Research, Kaduna, Kaduna State, Nigeria.
Department of Community Medicine, Faculty of Clinical Sciences, College of Health Sciences, University of Jos, Jos, Plateau State, Nigeria.
PLoS Negl Trop Dis. 2025 Aug 7;19(8):e0012495. doi: 10.1371/journal.pntd.0012495. eCollection 2025 Aug.
Onchocerciasis caused by the filarial parasite Onchocerca volvulus and transmitted by Simulium damnosum s.l. remains a public health concern in Nigeria. Infestation of S. damnosum s.l. along rivers Gurara and Kaduna; and heavy intensity of O. volvulus infection in Kaduna were documented in 1956. Control of onchocerciasis in Kaduna started 1954 with larviciding using dichlorodiphenyltrichloroethane reduced S. damnosum s.l. population by 94% in 1966. Diethylcarbamazine used for human treatment was discontinued due to toxicity. Kaduna State Ministry of Health and its partners built on this achievement; used annual mass administration of ivermectin consistently between 1989 and 2017 which led to interruption of onchocerciasis transmission in 2018. This study investigated possibility of recrudescence of onchocerciasis with the hypothesis that insecurity-induced migration could cause recrudescence of onchocerciasis.
METHODOLOGY/PRINCIPAL FINDINGS: Six out of the 23 Local Government Areas (LGAs) in Kaduna State were selected for evaluation. Adult S. damnosum s.l. were captured across seven breeding sites using human landing collectors from July to October 2023. Pooled screen assays of 72 pools heads of black flies were conducted using quantitative polymerase chain reaction (qPCR) for O. volvulus detection. Dried blood samples from 3107 children aged 5-9 years were collected; with 1502 samples analysed using alkaline phosphatase enzyme-linked immunosorbent assay due to financial constraints. Twenty pools of the 72 pools of heads (27.8%) of S. damnosum s.l. analysed were positive for O. volvulus in Kagarko and Kachia LGAs (> 1/2000 infective flies; 95% upper confidence limit 0.49) with qPCR prevalence of 0.32%. Two children from security compromised communities tested seropositive (prevalence 0.31%; 95% upper confidence limit 0.317).
CONCLUSION/SIGNIFICANCE: The findings demonstrated ongoing onchocerciasis transmission in Kaduna despite the interruption in 2018. This calls for evaluation of the extent of recrudescence and identification of key drivers such as human migration, fly movement and insecurity.
由丝状寄生虫盘尾丝虫引起、通过致倦库蚊传播的盘尾丝虫病在尼日利亚仍是一个公共卫生问题。1956年记录了致倦库蚊在古拉腊河和卡杜纳河沿岸的滋生情况，以及卡杜纳地区盘尾丝虫的高感染强度。卡杜纳的盘尾丝虫病防治工作始于1954年，使用二氯二苯三氯乙烷进行杀幼虫处理，1966年致倦库蚊数量减少了94%。用于人体治疗的乙胺嗪因毒性问题而停用。卡杜纳州卫生部及其合作伙伴在此基础上继续努力，在1989年至2017年期间持续进行伊维菌素的年度群体给药，这导致2018年盘尾丝虫病传播中断。本研究调查了盘尾丝虫病复发的可能性，假设不安全因素导致的迁移可能会导致盘尾丝虫病复发。
方法/主要发现：在卡杜纳州的23个地方政府辖区（LGAs）中，选择了6个进行评估。2023年7月至10月，使用人饵诱捕法在7个繁殖地点捕获成年致倦库蚊。对72组黑蝇头部进行混合筛查试验，采用定量聚合酶链反应（qPCR）检测盘尾丝虫。收集了3107名5至9岁儿童的干血样本；由于资金限制，对1502份样本采用碱性磷酸酶酶联免疫吸附测定法进行分析。在卡加尔科和卡基亚地方政府辖区，72组致倦库蚊头部样本中有20组（27.8%）通过qPCR检测盘尾丝虫呈阳性（>1/2000感染性苍蝇；95%置信上限0.49），患病率为0.32%。来自安全受影响社区的两名儿童血清学检测呈阳性（患病率0.31%；95%置信上限0.317）。
结论/意义：研究结果表明，尽管2018年盘尾丝虫病传播已中断，但卡杜纳地区仍存在盘尾丝虫病传播。这需要评估复发程度，并确定人类迁移、苍蝇活动和不安全等关键驱动因素。
