Department of Basic and Applied Biology, School of Sciences, University of Energy and Natural Resources, Sunyani, BA, Ghana.
Experimental Parasitology Unit, Department of Medical Microbiology, Academic Medical Centre, Amsterdam University Medical Centers, Amsterdam, The Netherlands.
Parasit Vectors. 2020 May 6;13(1):229. doi: 10.1186/s13071-020-04102-5.
Knowledge of the relative abundance and biting rates of riverine blackflies (vectors of onchocerciasis) is essential as these entomological indices affect transmission of the disease. However, transmission patterns vary from one ecological zone to another and this may be due to differences in species of blackfly vectors and the climatic conditions in the area. This study investigated the effects of climate variability on the relative abundance and biting rates of blackflies in the Tanfiano community (Nkoranza North District, Bono East Region, Ghana). Such information will help to direct policy on effective timing of the annual mass drug administration of ivermectin in the area.
The study employed human landing collections and locally built Esperanza window traps to collect blackflies from March 2018 to February 2019. The relative abundance and biting rates of the Simulium vectors as well as the monthly climatic conditions of the study area were monitored. Correlation analysis and Poisson regression were used to establish the relationships between the variables.
The relative abundance and biting rates of the Simulium vectors were highest in the drier months of March, April and August, characterized by high temperatures, low humidity, longer hours of sunshine and stronger winds. The rainy months of May, June and July, characterized by low temperatures, high humidity, few hours of sunshine and weaker winds, had relatively low blackfly abundance and biting activity. Correlation analysis showed that only temperature was significantly, positively correlated with the relative abundance of blackflies (r = 0.617, n = 12, P = 0.033) and monthly biting rates (r = 0.612, n = 12, P = 0.034). A model to predict relative abundance and monthly biting rates using climatological variables was developed.
This study demonstrated that Simulium species in the study area preferred higher temperature, lower humidity and rainfall, more hours of sunshine and relatively stronger winds for survival. It is thus recommended that for the study district and others with similar climatological characteristics, mass drug administration of ivermectin should take place in April and September when the abundance of vectors has begun to decline after peaking.
了解河栖黑蝇（盘尾丝虫病的传播媒介）的相对丰度和叮咬率至关重要，因为这些昆虫学指标会影响疾病的传播。然而，传播模式在不同的生态区之间存在差异，这可能是由于媒介黑蝇的物种差异以及该地区的气候条件不同所致。本研究调查了气候变异性对塔纳凡社区（博诺东地区诺克萨纳北区分区，加纳）黑蝇相对丰度和叮咬率的影响。这些信息将有助于指导该地区伊维菌素年度大规模药物治疗的有效时间安排。
本研究于 2018 年 3 月至 2019 年 2 月期间采用人类着陆采集和本地建造的 Esperanza 窗口陷阱收集黑蝇。监测了模拟向量的相对丰度和叮咬率以及研究区域的每月气候条件。采用相关分析和泊松回归来建立变量之间的关系。
3 月、4 月和 8 月气温较高、湿度较低、日照时间较长且风速较大，模拟黑蝇的相对丰度和叮咬率最高。5 月、6 月和 7 月雨水较多，温度较低、湿度较高、日照时间较少且风速较弱，黑蝇丰度和叮咬活动相对较低。相关分析表明，只有温度与黑蝇的相对丰度（r = 0.617，n = 12，P = 0.033）和每月叮咬率（r = 0.612，n = 12，P = 0.034）显著正相关。开发了一种使用气候变量预测相对丰度和每月叮咬率的模型。
本研究表明，研究区域内的 Simulium 物种更喜欢高温、低湿度和降雨、更多的日照时间和相对较强的风来生存。因此，建议在该研究区和其他具有类似气候特征的地区，在 4 月和 9 月进行大规模伊维菌素药物治疗，此时在高峰期过后，媒介的丰度开始下降。
