First Outbreak of West Nile Virus Neuroinvasive Disease in Humans, Croatia, 2012

Abstract

Between September 6 and 21, 2012, seven human cases of West Nile virus (WNV) neuroinvasive infection were laboratory confirmed in Croatia. The median patient age was 62 years (range 48-77). Five patients presented with meningoencephalitis and two patients with meningoencephalitis followed by acute flaccid paralysis. Four of them had an underlying disease (hypertension). Using enzyme-linked immunosorbent assay (ELISA), WNVspecific immunoglobulin M (IgM) and IgG antibodies of low avidity were detected in six patients, whereas one showed only IgM antibodies. All samples were confirmed using plaque-reduction neutralization and microneutralization tests. Five patients recovered fully. Before human cases were reported, acute asymptomatic WNV infection was demonstrated by detection of IgM antibodies in sentinel horses. Moreover, an increased WNV IgG seropositivity in horses was detected in counties where human cases occurred. Adulticidal and larvicidal treatments were administered immediately in the respective places of residence. The end of the warm season contributed to the fact that there were no new cases of WNV disease recorded.

Fatal Case of West Nile Neuroinvasive Disease in Bulgaria

“…A large outbreak of WNV lineage 2 infection occurred in Greece in 2010 ( 4 ). Outbreaks have also been reported in other countries in Europe, which showed spread of WNV lineage 2 ( 5 – 8 ). Some probable cases of West Nile fever were reported to the Bulgarian Ministry of Health on the basic of serologic test results.…”

West Nile virus retinitis in a patient with neuroinvasive disease

“…In August 2018, a 68-year-old patient with type II diabetes mellitus was admitted to the infectious disease department with a six-day history of fever (temperature up to 38.9°C), shivering, chills, vertigo, frontal headache, and fatigue. The patient came on holiday in a touristic area on the Adriatic Coast from the continental part of Croatia where autochthonous WNV infections have already been registered continuously from 2012 6,7 , as well as in the 2018 transmission season (unpublished data of the Reference Centre for Diagnosis and Surveillance of Viral Zoonoses, Croatian Ministry of Health, Croatian Institute of Public Health). In the coastal area, autochthonous human WNV infections had not been detected so far.…”

An overview of mosquitoes and emerging arboviral infections in the Zagreb area, Croatia

“…Since 2008 outbreaks in humans and horses have been frequently detected in many European countries: Greece, France, Hungary, Italy, Romania, Russia and Serbia [20,[27][28][29]. In 2012, the first outbreak of human WNV neuroinvasive disease was reported in Croatia with seven confirmed cases in three north-eastern counties [30]. In addition, acute asymptomatic infections in horses were noted in the same counties where human cases occurred [31].…”