Kolodziejek et al. Emerging Microbes & Infections (2018) 7:25
DOI 10.1038/s41426-018-0021-5
Emerging Microbes & Infections
ARTICLE Open Access
Integrated analysis of human-animal-vector
surveillance: West Nile virus infections in
Austria, 2015–2016
Jolanta Kolodziejek
1
, Christof Jungbauer
2
,StephanW.Aberle
3
, Franz Allerberger
4
,ZoltánBagó
5
,JeremyV.Camp
1
,
Katharina Dimmel
1
, Phebe de Heus
6
, Michael Kolodziejek
1
, Peter Schiefer
5
, Bernhard Seidel
7
, Karin Stiasny
3
and
Norbert Nowotny
1,8
Abstract
The results of integrated human and veterinary surveillance for West Nile virus (WNV) infections in Austria during the
transmission seasons 2015 and 2016 are shown. Altogether WNV nucleic acid was detected in 21 humans, horses, wild
birds and mosquito pools. In detail: in four human clinical cases [two cases of West Nile fever (WNF) and two cases of
West Nile neuroinvasive disease (WNND)]; eight blood donors [among 145,541 tested donations], of which three
remained asymptomatic and five subsequently developed mild WNF; two horses with WNND, of which one recovered
and one had to be euthanized; two wild birds [one goshawk and one falcon, both succumbed to WNND]; and five
Culex pipiens mosquito pools. Compared to previous years the number of infections increased remarkably. All
infections were recorded in the city of Vienna and neighboring regions of Lower Austria. Sixteen coding-complete
WNV sequences were established which were closely related to each other and to other Austrian, Czech and Italian
viruses, all belonging to the Central/Southern European cluster of WNV sublineage 2d. However, several genetically
slightly different WNV strains seem to co-circulate in the same area, as demonstrated by phylogenetic analysis. Based
on detailed sequence analysis, all newly discovered Austrian WNV strains had the potential to cause neurological
disease, but no correlation was found between severity of disease and the analyzed genetic virulence/
neuroinvasiveness markers. Results of integrated human-animal-vector surveillance presented in this paper provide a
comprehensive description of WNV activity in the region and will facilitate proactive public health measures to prevent
or mitigate potential outbreaks.
Introduction
West Nile virus (WNV) is a member of the genus Fla-
vivirus within the family Flaviviridae with almost world-
wide distribution. In nature it circulates between wild bird
hosts and certain mosquito vectors, mainly Culex sp.
Humans and horses are considered dead-end hosts.
About 80% of infected humans remain asymptomatic
while 20% develop mild febrile illness (West Nile fever,
WNF); less than 1% of cases present with encephalitis,
meningitis or encephalomyelitis (subsumed as West Nile
neuroinvasive disease, WNND) of which approx. 10%
die
1
. In equids, WNV infection is frequently also asymp-
tomatic or associated with fever, however it may also
result in encephalomyelitis with ataxia, paresis and
paralysis; in these cases mortality rate may reach 25%
2
.
Avian mortality is considered a good early indicator for
WNV activity in certain regions. Bird species such as
goshawks and other raptors are highly vulnerable to WNV
lineage 2 infection in central Europe and commonly
© The Author(s) 2018
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Correspondence: Norbert Nowotny (Norbert.Nowotny@mbru.ac.ae)
1
Viral Zoonoses, Emerging and Vector-Borne Infections Group, Institute of
Virology, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210
Vienna, Austria
2
Blood Service for Vienna, Lower Austria and Burgenland, Austrian Red Cross,
Wiedner Hauptstraße 32, 1040 Vienna, Austria
Full list of author information is available at the end of the article
Jolanta Kolodziejek and Christof Jungbauer contributed equally to this work.
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