Institute of Animal Hygiene and Veterinary Public Health, Faculty of Veterinary Medicine, Leipzig University, 04103 Leipzig, Germany.
Department for Horses, Faculty of Veterinary Medicine, Leipzig University, 04103 Leipzig, Germany.
Viruses. 2023 Apr 30;15(5):1108. doi: 10.3390/v15051108.
Since 2018, autochthonous West Nile virus (WNV) infections have been regularly reported in eastern-central Germany. While clinically apparent infections in humans and horses are not frequent, seroprevalence studies in horses may allow the tracing of WNV and related flaviviruses transmission, such as tick-borne encephalitis virus (TBEV) and Usutu virus (USUV), and consequently help to estimate the risk of human infections. Hence, the aim of our study was to follow the seropositive ratio against these three viruses in horses in Saxony, Saxony Anhalt, and Brandenburg and to describe their geographic distribution for the year 2021. In early 2022, i.e., before the virus transmission season, sera from 1232 unvaccinated horses were tested using a competitive pan-flavivirus ELISA (cELISA). In order to estimate the true seropositive ratio of infection with WNV, TBEV, and USUV for 2021, positive and equivocal results were confirmed by a virus neutralization test (VNT). In addition, possible risk factors for seropositivity using questionnaires were analyzed using logistic regression based on questionnaires similar to our previous study from 2020. In total, 125 horse sera reacted positive in the cELISA. Based on the VNT, 40 sera showed neutralizing antibodies against WNV, 69 against TBEV, and 5 against USUV. Three sera showed antibodies against more than one virus, and eight were negative based on the VNT. The overall seropositive ratio was 3.3% (95% CI: 2.38-4.40) for WNV, 5.6% (95% CI: 4.44-7.04) for TBEV, and 0.4% (95% CI: 0.14-0.98) for USUV infections. While age and number of horses on the holding were factors predicting TBEV seropositivity, no risk factors were discovered for WNV seropositivity. We conclude that horses are useful sentinels to determine the flavivirus circulation in eastern-central Germany, as long as they are not vaccinated against WNV.
自 2018 年以来，东德中部地区（德国东部和中部）定期报告本土西尼罗河病毒（WNV）感染病例。虽然人类和马匹的临床显性感染并不常见，但对马匹进行血清学检测可追踪WNV 和相关黄病毒（如蜱传脑炎病毒[TBEV]和乌苏图病毒[USUV]）的传播情况，进而帮助评估人类感染的风险。因此，我们的研究目的是跟踪萨克森州、萨克森-安哈特州和勃兰登堡州马匹对这三种病毒的血清阳性率，并描述它们在 2021 年的地理分布。2022 年初，即在病毒传播季节之前，使用竞争泛黄病毒 ELISA（cELISA）检测了 1232 份未接种疫苗的马血清。为了估算 2021 年 WNV、TBEV 和 USUV 感染的真实血清阳性率，对阳性和可疑结果进行了病毒中和试验（VNT）确认。此外，还使用问卷调查分析了可能的血清阳性风险因素，该问卷基于我们 2020 年类似的研究。总共有 125 份马血清在 cELISA 中呈阳性反应。基于 VNT，40 份血清对 WNV 具有中和抗体，69 份对 TBEV 具有中和抗体，5 份对 USUV 具有中和抗体。3 份血清对一种以上病毒呈阳性反应，8 份血清基于 VNT 呈阴性反应。WNV 的总血清阳性率为 3.3%（95%CI：2.38-4.40），TBEV 为 5.6%（95%CI：4.44-7.04），USUV 为 0.4%（95%CI：0.14-0.98）。年龄和畜群中马匹数量是 TBEV 血清阳性的预测因素，而WNV 血清阳性没有发现风险因素。我们的结论是，只要马不对 WNV 进行疫苗接种，它们就是确定东德中部地区黄病毒循环的有用监测者。
