Pathogens spread by high-flying wind-borne mosquitoes

Mosquito-borne diseases such as malaria and dengue threaten billions of people and cause the death of hundreds of thousands annually. Recent studies have revealed that many mosquito species regularly engage in high-altitude wind-borne migration, but its epidemiological significance remains unclear. The hypothesis that high-flying mosquitoes spread pathogens over long distances has not been directly tested. Here, we report that high-flying mosquitoes are commonly infected with arboviruses, protozoans, and helminths and provide a insights into this pathogen-vector aerial network. A total of 1,017 female mosquitoes intercepted on nets suspended from helium balloons at 120 to 290 m above ground over Mali and Ghana were screened for infection with arboviruses, Haemosporida, and filariae. The mosquitoes collected at altitude comprised 61 species, across 10 genera, dominated by Culex, Aedes, and Anopheles. Infection and infectiousness (capacity to transmit a pathogen to another host inferred based on disseminated infection) rates of migrant mosquitoes were 7.2% and 4.4% with Plasmodium spp., 1.6% and 0.6% with filariae, and 3.5% and 1.1% with flaviviruses, respectively. Twenty-one mosquito-borne pathogens were identified, including Dengue, West Nile, and M'Poko viruses, 15 avian Plasmodium species including Plasmodium matutinum, and three filariids, including Pelecitus sp. Confirmed head-thorax (disseminated) infections of multiple pathogens in Culex perexiguus, Mansonia uniformis, and Anopheles squamosus reveal that pathogens carried by high-altitude wind-borne mosquitoes are capable of infecting hosts far from their departure location. This high-altitude traffic of sylvatic pathogens (circulating in wild animals) may be key to their maintenance among enzootic foci as well as initiating outbreaks at distant locations.