West Nile Virus (WNV) is a flavivirus, which was first isolated in Uganda 1937. This virus has attracted attention in the past years. WNV is one of the worlds most widespread flaviviruses and has caused recent outbreaks among humans and animals. West Nile Fever (WNF) is a mosquito borne zoonotic disease. The last decade the epidemiological pattern of the virus and the severity of the outbreaks have changed. This article reviews the epidemiological changes and current situation of WNF, presents a case report and evaluates the risk for a possible outbreak in Sweden.