Abstract
BackgroundDuring the last decade, the spread of many flaviviruses (Genus Flavivirus) has been reported, representing an emerging threat for both animal and human health. To further study utility of wild ruminant samples in West Nile virus (WNV) surveillance, we assessed spatio–temporal trends and factors associated with WNV and cross-reacting flaviviruses exposure, particularly Usutu virus (USUV) and Meaban virus (MBV), in wild ruminants in Spain. Serum samples from 4693 wild ruminants, including 3073 free-living red deer (Cervus elaphus), 201 fallow deer (Dama dama), 125 mouflon (Ovis aries musimon), 32 roe deer (Capreolus capreolus) and 1262 farmed red deer collected in 2003–2014, were screened for WNV and antigenically-related flavivirus antibodies using a blocking ELISA (bELISA). Positive samples were tested for neutralizing antibodies against WNV, USUV and MBV by virus micro-neutralization tests.ResultsMean flavivirus seroprevalence according to bELISA was 3.4 ± 0.5 % in red deer, 1.0 ± 1.4 % in fallow deer, 2.4 ± 2.7 % in mouflon and 0 % in roe deer. A multivariate logistic regression model revealed as main risk factors for seropositivity in red deer; year (2011), the specific south-coastal bioregion (bioregion 5) and presence of wetlands. Red deer had neutralizing antibodies against WNV, USUV and MBV.ConclusionsThe results indicate endemic circulation of WNV, USUV and MBV in Spanish red deer, even in areas without known flavivirus outbreaks. WNV antibodies detected in a free-living red deer yearling sampled in 2010, confirmed circulation this year. Co-circulation of WNV and USUV was detected in bioregions 3 and 5, and of WNV and MBV in bioregion 3. Sampling of hunted and farmed wild ruminants, specifically of red deer yearlings, could be a complementary way to national surveillance programs to monitor the activity of emerging flaviviruses.
Highlights
During the last decade, the spread of many flaviviruses (Genus Flavivirus) has been reported, representing an emerging threat for both animal and human health
Mortality associated with Louping-ill virus (LIV) infection was detected in sheep and goats in northern sampled in Canary Islands (Spain) [16] and suspected in chamois (Rupicapra pyrenaica) [17]
As red deer is an important game species in Spain [28] and is frequently farm raised, it could be an accessible, cost-effective species to use as a complementary tool to the national surveillance programs to monitor the activity of mosquito-borne flaviviruses [27]
Summary
The spread of many flaviviruses (Genus Flavivirus) has been reported, representing an emerging threat for both animal and human health. The distribution of vector-borne flaviviruses (family Flavi viridae) in the world has substantially increased over the last decades During this period, many flavivirus infections have become a major public health concern due to continuous and growing reporting of outbreaks in humans [1]. Flaviviruses are mainly transmitted within an enzootic cycle involving ornithophilic mosquitoes or ticks as During the last few years, six flaviviruses, including West Nile virus (WNV), Usutu virus (USUV), tick-borne encephalitis virus (TBEV), Bagaza virus (BAGV), Meaban virus (MBV) and louping-ill virus (LIV), have been detected in Europe [2, 3]. Clinical disease and mortality associated with WNV infection has been detected in wild birds, horses and humans in this country [11, 12]. Meaban virus (MBV) has been found in both yellow-legged gulls (Larus michaelis) and ticks (Ornithodoros maritimus) in north-eastern Spain [3]
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