Integrated analysis of human-animal-vector surveillance: West Nile virus infections in Austria, 2015-2016.

This research article presents the findings from a surveillance study of West Nile virus (WNV) in Austria during 2015-2016, indicating a notable increase in infections in humans, horses, wild birds, and mosquitoes compared to previous years. The study showed that several genetically slightly different WNV strains were co-circulating in the same area, all having a potential to cause neurological disease.

Integrated Surveillance for West Nile Virus Infections:

• The researchers conducted an integrated human and veterinary surveillance for WNV infections during 2015-2016 to monitor and keep track of the spread of the virus among different species.
• Such an integrated approach provided a comprehensive view of the current situation and will aid in predicting and controlling potential outbreaks in the future.
• The surveillance was particularly focused on Vienna and neighboring regions of Lower Austria.

Results of the Surveillance Study:

• A total of 21 WNV nucleic acid detections were made across humans, horses, wild birds, and mosquito pools.
• The virus was found in four human clinical cases and eight blood donors out of a total 145,541 tested donations. Among infected blood donors, three remained asymptomatic while five developed mild West Nile fever (WNF).
• The screening also detected two cases of WNV in horses with West Nile neuroinvasive disease (WNND), leading to the euthanization of one.
• Two wild birds succumbed to WNND, and five Culex pipiens mosquito pools tested positive for WNV.
• Compared to previous years, there was a remarkable increase in the number of detected infections, indicating a growing concern over the spread of WNV.

Genetic Analysis of the Detected WNV:

• A detailed sequence analysis of the detected WNV strains indicated 16 coding-complete WNV sequences which were closely related to each other as well as to strains from Austria, the Czech Republic, and Italy.
• All these strains belong to the Central/Southern European cluster of WNV sublineage 2d.
• The study also discovered that several genetically slightly different WNV strains seemed to co-circulate in the same area, as demonstrated by phylogenetic analysis.
• Each of these newly discovered Austrian WNV strains had the potential to cause neurological disease. However, the researchers found no correlation between the severity of the disease and the analyzed genetic virulence/neuroinvasiveness markers.

Implications for Public Health:

• The findings from this integrated human-animal-vector surveillance study provide a comprehensive description of WNV activity in Vienna and neighboring regions of Lower Austria.
• This research will aid in implementing proactive public health measures to prevent or mitigate potential outbreaks in the future.