Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 22 BP 582, Abidjan 22, Côte d'Ivoire.
Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, 01 BP 1303, Abidjan 01, Côte d'Ivoire.
Parasit Vectors. 2020 Jul 2;13(1):337. doi: 10.1186/s13071-020-04188-x.
Preventive chemotherapy with praziquantel is the cornerstone of schistosomiasis control. However, in some social-ecological settings, the prevalence and/or intensity of Schistosoma infection does not lower meaningfully despite multiple rounds of preventive chemotherapy, a phenomenon termed persistent hotspot (PHS). We assessed the characteristics of PHS in a Schistosoma mansoni-endemic area of Côte d'Ivoire.
In October 2016, a cross-sectional survey was conducted in 14 schools in the western part of Côte d'Ivoire, one year after multiple rounds of preventive chemotherapy. In each school, 50 children aged 9-12 years provided two stool samples and one urine sample. Stool samples were subjected to triplicate Kato-Katz thick smears for S. mansoni diagnosis. Urine samples were examined by a filtration method for S. haematobium eggs. PHS was defined as failure to achieve a reduction in the prevalence of S. mansoni infection of at least 35% and/or a reduction of infection intensity of at least 50%. Six schools underwent more detailed investigations, including a questionnaire survey for demographic characteristics and a malacological survey.
In the six schools subjected to detailed investigations, the overall prevalence of S. mansoni and S. haematobium was 9.5% and 2.6%, respectively. Four schools were classified as PHS. The S. mansoni prevalence in the four PHS was 10.9% compared to 6.6% in the remaining two schools. The S. mansoni infection intensity, expressed as arithmetic mean eggs per gram of stool (EPG) among infected children, was 123.8 EPG in PHS and 18.7 EPG in the other two schools. Children bathing in open freshwater bodies were at higher odds of S. mansoni infection (odds ratio: 4.5, 95% confidence interval: 1.6-12.6). A total of 76 human-water contact sites (53 in PHS and 23 in the other schools) were examined and 688 snails were collected, including potential intermediate host snails of Schistosoma (Biomphalaria pfeifferi, Bulinus forskalii, Bu. globosus and Bu. truncatus).
Children in PHS schools bathed more frequently in open freshwater bodies, and hence, they are more exposed to Schistosoma transmission. Our findings call for an integrated control approach, complementing preventive chemotherapy with other interventions, particularly in PHS settings.
以吡喹酮进行的预防性化疗是血吸虫病控制的基石。然而，在某些社会-生态环境中，尽管进行了多轮预防性化疗，血吸虫感染的流行率和/或强度并没有显著降低，这种现象被称为持续热点（PHS）。我们评估了科特迪瓦曼氏血吸虫流行地区 PHS 的特征。
2016 年 10 月，在科特迪瓦西部的 14 所学校进行了横断面调查，这是在多轮预防性化疗一年后进行的。在每所学校中，50 名 9-12 岁的儿童提供了两份粪便样本和一份尿液样本。粪便样本采用 Kato-Katz 三重厚涂片法进行曼氏血吸虫诊断。尿液样本采用过滤法检查埃及血吸虫卵。将未能实现曼氏血吸虫感染流行率降低至少 35%和/或感染强度降低至少 50%的情况定义为 PHS。有六所学校进行了更详细的调查，包括人口统计学特征的问卷调查和贝类学调查。
在接受详细调查的六所学校中，曼氏血吸虫和埃及血吸虫的总流行率分别为 9.5%和 2.6%。四所学校被归类为 PHS。四所 PHS 学校的曼氏血吸虫流行率为 10.9%，而其余两所学校为 6.6%。曼氏血吸虫感染强度，以感染儿童粪便每克平均虫卵数（EPG）表示，在 PHS 为 123.8 EPG，而在另外两所学校为 18.7 EPG。在露天淡水体中洗澡的儿童感染曼氏血吸虫的可能性更高（比值比：4.5，95%置信区间：1.6-12.6）。共检查了 76 个人-水接触点（53 个在 PHS 中，23 个在其他学校），采集了 688 只蜗牛，包括血吸虫的潜在中间宿主蜗牛（Biomphalaria pfeifferi、Bulinus forskalii、Bu. globosus 和 Bu. truncatus）。
PHS 学校的儿童更频繁地在露天淡水体中洗澡，因此，他们更容易受到血吸虫传播的影响。我们的研究结果呼吁采取综合控制方法，在 PHS 环境中，除预防性化疗外，还应辅以其他干预措施。
