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COVID-19在撒哈拉以南非洲农村地区的传播知之甚少，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如何影响它，我们启动了一项新的非侵入性高通量COVID-19感染监测战略，每月在分布在500公里的20个马里村庄采集吸血蚊子样本。蚊子血粉将用于通过ELISA检测COVID 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，合作者将对居民进行血清学测试，作为他们自己项目的一部分，并将与我们分享匿名数据，以进行比较和验证。几个村庄正在测试几种出口陷阱设计和SOP优化。目前正在对地方工作队进行收集和保存蚊子的培训，同时还开展了蚊子标本的试点收集工作。我们预计到2020年9月，所有村庄都将接受培训并投入使用。 计划进行实验室实验，根据蚊子的血餐来确定感染状况，一旦关键试剂（例如，来自已暴露于COVID 19且具有平均IgG滴度的个体的阳性对照血清）将到达我们的实验室。我们的目标是确定血餐后的时间窗口，在给定两个广泛使用的表位的预期滴度的情况下，抗体检测是可靠的。

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.