[West Nile virus expanding in Europe].

The areas of Europe in which West Nile virus (WNV)-transmission to humans is observed have expanded over the last few years, with endemic circulation amongst animals of southern Europe. This situation calls for heightened vigilance to the clinical presentation of WNV infection in humans. The average incubation period lasts 2-6 days. Of those infected, 20% will experience a mild, non-specific disease presentation such as high fever, headache, myalgia, possibly with rash and lymphadenopathy; <1% will develop severe neurological symptoms. Rare complications include: myelitis, optic neuritis, rhombencephalitis, polyradiculitis, myocarditis, pancreatitis and fulminant hepatitis. Clinicians should take WNV infection into consideration when making a differential diagnosis for such symptoms in patients who have returned from areas with potential virus circulation. Given the increase in the spread of WNV within Europe, this now holds true for continental travellers as well as those destined for the Americas, Africa and Asia. It is important to include the patient's travel history, clinical symptoms and any occurrences of vaccination against viruses causing Japanese encephalitis, tick-borne encephalitis and yellow fever into the diagnostic workup, as the antibodies against these diseases show cross-reactivity.