[Usutu virus: a novel flavivirus in Croatia].

Usutu virus (USUV) belongs to the family Flaviviridae, genus Flavivirus, Japanese encephalitis serocomplex. The virus was discovered in 1959 in South Africa and has emerged since 1996 causing epizootics with high avian mortality in Europe. The importance of USUV in humans is not fully understood. However, several human clinical cases of USUV infection described so far indicate the role of this virus as an antropozoonotic agent. In Croatia, serologic evidence of USUV was first documented in 2011 in two horses from Zagreb and Sisak-Moslavina County. In 2012, USUV neutralizing antibodies were found in one human sample from a resident of a Vukovar-Srijem County. Human clinical cases of USUV infection were detected for the first time during the West Nile virus outbreak from July to September 2013. Three patients with USUV neuroinvasive disease were detected in the City of Zagreb and Zagreb County. Our results indicate USUV circulation in Croatia. Further human cases could be expected in the next transmission seasons.