Science - June 4, 2015

Our mosquito can transmit virulent virus

Albert Sikkema

The Dutch mosquito is perfectly capable of transmitting the West Nile virus to humans. If it gets hotter here and the virus invades from southern Europe, there is a big chance of increasing numbers of meningitis infections, reveals PhD research by Jelke Fros.

The West Nile virus originates in Africa. But there have been regular outbreaks in southern Europe in the past five years. An outbreak in Greece in 2010 led to 35 deaths. This is one of the reasons why the EU has made research funding available.

The virus multiplies in mosquitoes and in birds such as blackbirds and crows. Of all those infected, a small number end up with fever and a form of meningitis. It is similar to the Usutu virus which has been circulating in central Europe for a few years now. This virus, too, can be deadly. Neither of these virsuses have been found in Dutch mosquitoes. Fros investigated how effectively the common Dutch mosquito (Culex pipiens) can transmit both viruses. Tests showed that our mosquito effectively transmits both viruses, but that it does so more successfully at higher southern European temperatures. The chances of the Usutu virus reaching the Netherlands from central Europe are greater, but the West Nile virus too could end up in the Dutch mosquito at higher temperatures, concludes Fros.

What to do? ‘First of all, it is important to monitor the spreading of the virus very well during the hot summer months in southern Europe. Secondly, general practitioners should be aware of the advancing viruses so that they think of them earlier in cases of meningitis. Now they only consider them if a patient has been to the tropics. And thirdly, we need vaccines. These are quite easy to make, but to get them accepted you need clinical studies which are expensive and time-consuming. So you need a strong market player.’ 

Jelke Fros is due to receive his PhD on 5 June from Just Vlak, personal professor of Virology and William Takken, personal professor of Entomology.