West-Nijl-virus in opmars in Europa

Conflict of interest: none declared. Financial support: none declared.

• 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.