Anthonioz Corinne, Abadie Yann, Reversat Elodie, Lafargue Annie, Delalande Manon, Renaudineau Thierry, Delobel Laurent, Verdeille Nathalie, Ngwa-Mbot David, Gache Kristel, Garin Emmanuel, Corbiere Fabien
Groupement de Défense Sanitaire (Animal Health Farmers' Organization) du Tarn et Garonne, Montauban, France.
Groupement de Défense Sanitaire (Animal Health Farmers' Organization) des Hautes-Pyrénées, Tarbes, France.
Front Vet Sci. 2025 May 14;12:1562883. doi: 10.3389/fvets.2025.1562883. eCollection 2025.
The emergence of Epizootic Hemorrhagic Disease Virus-8 (EHDV-8) in mainland France in 2023 led to thousands of clinical outbreaks in cattle herds and likely led to the natural immunization of a large number of animals. However, uncertainties persist regarding the extent of this immunity, both within herds and across affected regions. This study therefore aimed at investigating the variability of within-herd seroprevalence in clinically affected and non-affected herds across geographical areas with differing levels of disease incidence.
A study was launched in February 2024 to assess the variability of within-herd seroprevalence in three geographical areas with varying EHDV-8 clinical incidence. A total of 2,763 serums samples from cattle over 24 months in 30 herds with clinical outbreaks and 31 herds without reported clinical case were analyzed using a commercial competitive ELISA.
A strong south-north seroprevalence gradient was observed, with the highest animal-level seroprevalence evidenced in the southernmost zone (Pyrenean Piémont) (82.6%, CI 95%: 81.1-83.9), which also experienced the highest incidence of clinical outbreaks. In contrast, significantly lower seroprevalence levels were found in the more northern areas: (zone 2: 11.6, 95% CI: 10.7-12.7; zone 3: 0.3, 95% CI: 0.1-1.1), where clinical outbreaks were less frequent. The within-herd seroprevalence varied widely among herds but was significantly higher in those located in the southernmost zone, compared to other areas. Within each zone, no significant differences in seroprevalence were observed between clinical outbreak herds and non-outbreak herds.
This study highlights significant geographic and between herd variability in seroprevalence against EHDV-8 after the major virus circulation experienced in 2023, and provides critical insights into regional risks and the potential impact of future EHDV-8 circulation.
2023年法国大陆出现的8型流行性出血病病毒（EHDV - 8）导致牛群中出现数千起临床疫情，可能使大量动物获得了自然免疫。然而，无论是在畜群内部还是在受影响地区，这种免疫力的程度仍存在不确定性。因此，本研究旨在调查在疾病发病率不同的地理区域内，临床发病和未发病畜群中畜群内血清阳性率的变异性。
2024年2月启动了一项研究，以评估在三个EHDV - 8临床发病率不同的地理区域内畜群内血清阳性率的变异性。使用商业竞争ELISA法对来自30个有临床疫情的畜群和31个无临床病例报告的畜群中24个月以上牛的2763份血清样本进行了分析。
观察到明显的南北血清阳性率梯度，最南端地区（比利牛斯山麓）动物水平的血清阳性率最高（82.6%，95%置信区间：81.1 - 83.9），该地区临床疫情的发病率也最高。相比之下，在更北部的地区血清阳性率水平显著较低：（区域2：11.6，95%置信区间：10.7 - 12.7；区域3：0.3，95%置信区间：0.1 - 1.1），这些地区临床疫情较少。畜群内血清阳性率在不同畜群之间差异很大，但与其他地区相比，最南端地区的畜群血清阳性率显著更高。在每个区域内，临床疫情畜群和非疫情畜群之间的血清阳性率没有观察到显著差异。
本研究强调了在2023年主要病毒传播之后，针对EHDV - 8的血清阳性率存在显著的地理和畜群间变异性，并为区域风险以及未来EHDV - 8传播的潜在影响提供了关键见解。
