West Nile Fever With Other Complications

West Nile virus (WNV) is a mosquito-borne virus which in majority of cases causes only self-limited disease. Despite that, in minority of cases (\~0.5%) it can infect the brain and cause severe and even life-threatening disease (neuroinvasive disease). Recent study has shown that up to 40% of WNV patients who develop neuroinvasive disease, have antibodies against Interferons (anti-Type I interferon autoantibodies), which neutralizes interferons, and could explain the development of severe disease. The investigators therefore assume that early treatment with interferon beta (the type of interferon against which most patients do not have neutralizing antibodies) could prevent the development of severe neuroinvasive WNV disease.