Seroprevalence and risk factor analysis for exposure to equine encephalosis virus in Israel, Palestine and Jordan.

Sharon Tirosh-Levy,Ziad Abdeen,Lara Quraan,Boris Gelman,Amir Steinman,Evgeny Khinich,Doni Zivotofsky,Abdelmajeed Nasereddin

doi:10.1002/vms3.58

Abstract

Equine encephalosis virus (EEV) is an orbivirus transmitted by Culicoides species. Most infected horses show mild clinical signs and mortality is usually very low. EEV is closely related and similarly transmitted to other, more pathogenic and economically important, orbiviruses such as African horse sickness virus (AHSV), bluetongue virus (BTV) and epizootic haemorrhagic disease viruses (EHDV), and may serve as an indicator for possible transmission of the latter. Israel has been reported to be endemic for EEV since 2001. This study was initiated to re‐evaluate the current seroprevalence and risk factors for EEV exposure in Israel, and to assess, for the first time, the seroprevalence of EEV in Palestine and Jordan. Three hundred and sixteen serum samples were collected from apparently healthy horses at 21 farms in Israel, 66 horses at nine farms in Palestine and 100 horses at three farms in Jordan. The presence of EEV antibodies was detected by a serum neutralization assay. Seroprevalence of EEV was 58.2% (184/316 horses) in Israel, 48.5% (32/66 horses) in Palestine and 2% (2/100 horses) in Jordan. Seroprevalence in Jordan was significantly lower than in Israel and Palestine (P < 0.001). The farm (P < 0.001) and horse age (P = 0.003) were found as significant risk factors for EEV exposure in Israel in multivariable statistical analysis. The results of this study further demonstrate that EEV is no longer limited to South Africa and is endemic in both Israel and Palestine and horses in Jordan were also exposed to this virus emphasizing the potential of pathogens to invade new ecological niches.

Highlights

Equine encephalosis virus (EEV) is an arthropodborne virus of equids that belongs to the genus Orbivirus and the family Reoviridae, and is transmitted by several midge (Culicoides) species
EEV is closely related to other orbiviruses including African horse sickness virus (AHSV), which can cause a highly fatal disease in horses; bluetongue virus (BTV) and epizootic haemorrhagic disease virus (EHDV), which both have significant veterinary and economic effects on ruminants (Attoui & Jaafar 2015)
Many of the farms located in the north and Golan Heights kept the horses in pasture (117 horses, 37%), the rest of the horses were housed either in stalls (118 horses, 37.3%) of paddocks (81 horses, 25.6%)

Summary

Introduction

Equine encephalosis virus (EEV) is an arthropodborne virus of equids that belongs to the genus Orbivirus and the family Reoviridae, and is transmitted by several midge (Culicoides) species. Since all the mentioned orbiviruses are transmitted by Culicoides biting midges, many similar environmental parameters may influence their prevalence and distribution. Prior to 2008 EEV was only known to be endemic in South Africa, with seven serotypes circulating in the area (Howell et al 2002, 2008). Since it was reported in several locations in East and West Africa, as well as in Israel (Mildenberg et al 2009; Oura et al 2012; Attoui & Jaafar 2015). Retrospective studies from Israel demonstrated that this virus was present in the horse population from at least 2001 (Wescott et al 2013), and that the prevalent strain in Israel was more similar to a strain isolated

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Conclusion