Abstract
A crucial, but unresolved question concerning mosquito-borne virus transmission is how these viruses can remain endemic in regions where the transmission is halted for long periods of time, due to mosquito inactivity in, e.g., winter. In northern Europe, Sindbis virus (SINV) (genus alphavirus, Togaviridae) is transmitted among birds by Culex mosquitoes during the summer, with occasional symptomatic infections occurring in humans. In winter 2018–19, we sampled hibernating Culex spp females in a SINV endemic region in Sweden and assessed them individually for SINV infection status, blood-feeding status, and species. The results showed that 35 out of the 767 collected mosquitoes were infected by SINV, i.e., an infection rate of 4.6%. The vast majority of the collected mosquitoes had not previously blood-fed (98.4%) and were of the species Cx. pipiens (99.5%). This is the first study of SINV overwintering, and it concludes that SINV can be commonly found in the hibernating Cx. pipiens population in an endemic region in Sweden, and that these mosquitoes become infected through other means besides blood-feeding. Further studies on mosquito ecology and viral interactions are needed to elucidate the mechanisms of the persistence of these viruses over winter.
Highlights
Mosquitoes are vectors of many viruses responsible for causing disease in humans
Our results show that infection rates in the hibernating Cx. pipiens investigate if Sindbis virus (SINV) can persist through winter in the hibernating mosquito population, and whether population are high, and that the majority of infected females have not taken a blood meal before these females have taken a blood meal prior to hibernation
767 individual mosquitoes were morphologically identified as Cx. pipiens/torrentium females
Summary
Mosquitoes are vectors of many viruses responsible for causing disease in humans. Despite much research effort, many basic questions on the impact of mosquito ecology on virus transmission remain. One of the most intriguing unresolved questions is how viruses persist over periods of low or non-existing vector activity, such as dry or cold seasons. In temperate regions, this can correspond to months of vector inactivity over winter, which has impact on transmission of viruses such as. The mechanism that has gathered most scientific evidence is virus persistence in inseminated, hibernating mosquito females. Both JEV and WNV have been found in hibernating females in Asia and North America/Europe, respectively [1,2,3,4,5]. Reported infection rates are usually low, and most studies showed that the majority of hibernating females had never taken a blood-meal, precluding the conventional route of infection trough blood-feeding [1,6,7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
