West-Nil-Virus - Ursache einer Zoonose mit zunehmender Bedeutung?

The epidemic West Nile Virus (WNV) infections observed in the last years, particularly those in the USA in 1999 and the following years, have led to an increasing interest in this zoonotic infection. Here, the most prominent aspects of WNV biology and epidemiology are presented. Clinical signs observed in men and horses are described, as well as the current state of diagnostics and immunoprophylaxis. Preliminary results of investigations on the prevalence of WNV in Germany show that migrating birds have been in contact with WNV; there is however no indication for the presence of this virus. While WNV is endemic in many parts of the "Old World", thus inducing "natural immunity" in (migrating) birds and vertebrates, a susceptible bird population with no existing immunity against this virus was exposed in the "New World".