Evaluating the determinants of the spread of COVID-19 between and within rural communities in Mali, West Africa based on blood-fed mosquitoes

人们对新冠肺炎在撒哈拉以南非洲农村地区的传播情况知之甚少，也不太可能获得可靠的数据。为了填补这一空白并评估独特的生态和文化环境对其的影响，我们启动了一项新的战略，通过对分布在500公里的马里20个村庄每月收集的吸血蚊子进行采样，对新冠肺炎感染进行非侵入性、高通量监测。蚊血粉将用于检测柯萨奇病毒19抗体。 目前，所有20个村庄的招募工作已经完成，其中包括3个村庄，合作者将在他们自己的项目中对居民进行血清学测试，并将与我们分享匿名数据以进行比较和验证。几个村庄正在对几种出口隔热装置设计和SOP优化进行测试。目前正在对当地团队进行蚊子采集和保存方面的培训，同时已经开始试行蚊子标本采集工作。我们预计，到2020年9月，所有村庄都将接受培训并投入使用。 现正计划进行实验室实验，以确定基于蚊血粉的感染状况，并将在关键试剂(例如，接触过COVID19并具有平均免疫球蛋白滴度的人的阳性对照血清)到达我们实验室后立即开始。我们的目标是确定血餐后抗体检测可靠的时间窗口，给出两个广泛使用的表位的预期滴度。

The spread of COVID-19 in rural sub-Saharan Africa is poorly understood and reliable data are unlikely to be obtained. To fill this gap and assess how the unique ecological and cultural settings affect it, we have initiated a novel strategy of non-invasive, high throughput monitoring of COVID-19 infections by sampling blood-fed mosquitoes collected monthly in 20 Malian villages spread across 500km. The mosquito blood meal will be used to detect antibodies against COVID19 by ELISA. Presently, recruitment of all 20 villages has been completed including 3 villages where collaborators will carry out serological tests on residents as part of their own projects and will share anonymous data with us for comparison and validation. Testing of several exit trap designs and SOP optimization are ongoing in several villages. Training of local teams in mosquito collection and preservation is ongoing, while pilot collection of mosquito specimens has been implemented. We expect that all villages will be trained and operational by September 2020. Laboratory experiments to identify infection status based on mosquito blood meals are planned and will start as soon as the key reagents (e.g., positive control sera from individuals who have been exposed to COVID19 and who have an average titer of IgG) will arrive to our laboratory. Our goal is to determine the window of time after blood meal that detection of antibodies is reliable, given expected titer for two widely used epitopes.