Clinical impact, diagnosis and control of Equine Herpesvirus‐1 infection in Europe

Abstract

Equine herpesvirus‐1 (EHV‐1) can affect the entire equine sector in EU, and the large outbreak reported in 2021 in Spain drew attention to the needs of the European Commission for scientific advice for the assessment of EHV‐1 infection within the framework of Animal Health Law. EHV‐1 is considered endemic in the EU; its main risk is linked to the characteristic of producing latent life‐long infections. These can reactivate producing clinical disease, which can include respiratory, abortive and possibly fatal neurological forms. From the epidemiological and genomic viewpoint, there are no specific neuropathogenic EHV‐1 strains; the respiratory, reproductive and neurological signs are not found to be strain‐specific. This was also the case of the virus that caused the outbreak in Valencia (Spain) in 2021, which was genetically closely related to other viruses circulating before in Europe, and did not present the so‐called neuropathogenic genotype. The outbreak reported in Valencia was followed by wide geographic spread of the virus possibly due to a delay in diagnosis and late application of biosecurity measures. The recommended and most sensitive diagnostic test for detecting EHV‐1 is PCR performed on swabs collected according to the type of clinical signs. Serological assays on paired blood samples can help to detect a recent infection, while no diagnostic methods are available to detect EHV‐1 latent infections. Safe movements of horses can be ensured at premovement phase by testing and issuing health certificates, and by isolating animals upon arrival at new premises with regular health monitoring. In case of suspicion, movements should be forbidden and EHV‐1 infection early detected/confirmed by validated diagnostic tools. During outbreaks, no movements should be allowed until 21 days after the detection of the last case. In general, vaccination against EHV‐1 should be promoted, although this offers limited protection against the neurological form of the disease.

Detection of infectious agents in equine pregnancy loss, stillbirth and neonatal death

“…Belgium is known for its important role in equine breeding, and it is also a popular equestrian sports country. Consequently, there is a higher chance of direct contact between animals, which may lead to new outbreaks of EHV-1, as already shown in the past (Carvelli et al, 2022). In other important horse breeding areas, such as the USA and UK, EHV-1 positive cases have declined over time, which was attributed to a combination of vaccination and improved risk reduction (Macleay et al, 2022).…”

First report of Leishmania (Mundinia) martiniquensis in South American territory and confirmation of Leishbunyavirus infecting this parasite in a mare

“…For sports competitions, the horses may be frequently transported to other regions of the same country or abroad, increasing the risks of spreading infectious diseases 55 such as leishmaniases. 14 Therefore, the mare of this study may have been infected due to travel for sports competition to the region of Itaipuaçu, in the municipality of Maricá, State of Rio de Janeiro, Brazil, that is endemic for leishmaniases.…”

Overview of the causes of abortion in horses, their follow‐up and management

“…To confirm clinical suspicion, diagnosis by PCR is now preferred because it gives a result faster than other techniques (culture, histology, etc. ), which speeds up the implementation of preventive measures to avoid an epidemic (EFSA, 2022).…”