EHV‐1 neurological outbreak during a show‐jumping competition: a clinical and epidemiological study

Anne Couroucé (1, 2, 3) , C. Tessier (1) , R. Pomares (4) , J. Thévenot (5) , Christel Marcillaud Pitel (3) , Stéphane Pronost (2, 6) , Loïc Legrand (6, 2) , Pierre-Hugues Pitel (6)

1 ONIRIS - École nationale vétérinaire, agroalimentaire et de l'alimentation Nantes-Atlantique
2 BIOTARGEN - Biologie, génétique et thérapies ostéoarticulaires et respiratoires
3 RESPE - Réseau d'Epidémio-Surveillance en Pathologie Équine
4 Clinique vétérinaire LD Le Tremoulet
5 Clinique vétérinaire d'Issus
6 LABÉO - LABÉO, Pôle d’analyses et de recherche de Normandie

Background: A total of 753 horses were involved in the CES Valencia (Spain) Spring Tour 2021. Due to an EHV-1 outbreak, the competition was cancelled and the site was locked down with 157 horses from 15 different nations staying on site. Objectives: Describe epidemiological, clinical, diagnostic, treatment and outcome data on a population of horses staying in Valencia. Study design: Retrospective clinical study. Methods: From the 157 horses on site, 60 horses were followed (32 mares, 24 geldings and 4 stallions) and 67 were sampled with nasopharyngeal swabs sent to Labeo. Results: From the 60 horses, 10 showed no signs (no fever, no neurological signs). A total of 50 horses showed fever between 38.6 and 41.2°C which lasted for 4.0±2.1 days. Of these, 60% showed no further signs and 40% showed neurological signs with 8 horses hospitalised, of which 2 died. Neurological signs included either ataxia, urinary problems with bladder atony and lack of tail tone. For the mares, 75% showed fever and of these 50% showed neurological signs. For the geldings, 91.7% showed fever and of these 31.8% showed neurological signs. For the 4 stallions, all showed fever and one showed neurological signs. The mean duration between the last day of fever and the beginning of neurological signs was 1.05±1.32 days. There were 33 vaccinated horses (31 had a booster less than 6 months prior to the show): 96.9% showed fever of which 45.4% showed neurological signs. Among the 27 non-vaccinated horses, 66.7% showed fever of which 27.8% showed neurological signs. EHV-1 was detected by qPCR, genotyped as A2254 (ORF30) and isolated on cell culture.

Domaines: Médecine vétérinaire et santé animale

Anne Couroucé, C. Tessier, R. Pomares, J. Thévenot, Christel Marcillaud Pitel, et al.. EHV‐1 neurological outbreak during a show‐jumping competition: a clinical and epidemiological study. 11th International Equine Infectious Diseases Conference, Sep 2021, Online, France. pp.52-52, ⟨10.1111/evj.75_13495⟩. ⟨hal-03374585⟩