West-Nile Virus

West Nile fever is caused by a virus transmitted by mosquitoes and whose reservoir hosts include wild birds and mosquitoes. Humans are mainly infected through mosquito bites, but infection can occur through organ transplantation and blood transfusion.

An incubation period of three to 14 days precedes symptoms. However, most human infections are asymptomatic. The majority of clinical cases are mild and present with flu-like symptoms. Severe cases with signs of encephalitis or meningitis are most often observed among the elderly. No specific therapy or vaccine is currently available.

As it affects countries in Europe every year, West Nile fever is now recognised as a major public health concern in this region. The main preventive measures are aimed at reducing exposure to mosquito bites.


Source: European Centre for Disease Prevention and Control. Epidemiological update: West Nile virus transmission season in Europe, 2015.