Equine Infectious Anemia Virus in Equids : A Large-Scale Serosurvey in Western Europe

Equine Infectious Anemia (EIA) is a notifiable disease caused by Equine Infectious Anemia Virus (EIAV), posing significant sanitary and economic risks to equids worldwide. Data on EIAV circulation in Western Europe remain scarce and outdated. This cross-sectional study assessed EIAV seroprevalence in 1676 equids (1444 horses, 106 donkeys, and 126 mules/hinnies) from Southern Spain, Northeastern Spain, Southeastern United Kingdom, and Ireland between 2011 and 2023. We did not detect antibodies against EIAV in the equids analyzed. Our results are in line with those previously reported in Western Europe and support the effectiveness of current surveillance and control measures implemented in accordance with national and international regulations to successfully limit EIAV circulation. Background: Equine Infectious Anemia (EIA) is a notifiable disease caused by Equine Infectious Anemia Virus (EIAV), with major sanitary and economic importance for equids worldwide. There is limited and outdated information on the circulation of EIAV in many European countries. In the present study, we aimed to assess virus exposure in different equid species in Western Europe. Methods: Between 2011 and 2023, a cross-sectional study was conducted to investigate the seroprevalence of EIAV in 1676 equids (1444 horses, 106 donkeys and 126 mules/hinnies) from four European regions: Andalusia (Southern Spain; n = 808), Catalonia (Northeastern Spain; n = 437), Southeastern United Kingdom (UK; n = 209), and Ireland (n = 222). Results: None of the analyzed equines tested positive for antibodies against EIAV (0%; 95 %CI: 0.0-0.18), indicating limited virus exposure of the equid populations from these European regions. Conclusions: This finding is consistent with the low EIAV circulation previously reported in Western Europe and the few official EIA outbreaks recorded in the region during the last decade. To the best of the author's knowledge, this serosurvey represents the first investigation assessing EIAV exposure in equids from Ireland and the UK. Our results not only provide novel epidemiological evidence for the four European regions assessed but also reinforce the effectiveness of surveillance strategies and control measures implemented by European countries, in accordance with national and international regulations, to successfully limit EIAV circulation.