Equine Herpes Virus-1 (EHV-1) Neurological Disease Update

 

Equine Industries Committee – EHV-1 neurological disease outbreak – Further Information 11th March 2021

Guillaume Fortier, Richard Newton and Sidney Ricketts met remotely on 10th March 2021 to discuss the virological test results and epidemiological evidence emerging from horses at or returning home (throughout Europe) with respiratory or neurological signs of EHV-1 infection, following the equine showjumping event held initially at Valencia, Spain and subsequently at other sites in Spain and Portugal.

Further evidence and information will continue to emerge, but at this stage and on the basisof information that we currently have, we believe that:

1. The virus involved is not the so called ‘neuropathogenic strain’ (G2254/D752) as multiple samples have been classified as non-neuropathogenic (A2254/N752). This
work was done at LABÉO, France, on samples provided through the RESPE network.
2. The virus involved appears to be a previously commonly circulating strain in Europe based on application of multi-locus sequence typing (MLST type) (work similarly
done at LABÉO, France, on samples provided through the RESPE network) but results of whole genome sequencing of viral isolates are not yet available but will provide
the greatest discrimination between any different viruses involved. Collaborative work between LABÉO, France and the Irish Equine Centre is on-going.
3. Epidemiological evidence from International Collating Centre (ICC) reports suggest that neurological cases are primarily seen in horses directly involved in these events, either at the event or after travelling home. Onward transmission at home stables to in contact horses that were not at the event, appear to mainly involve signs of respiratory disease or subclinical infection detected through screening testing.
4. Further laboratory and epidemiological evaluations will follow with time but at this stage we suspect that circumstances occurred at the event to allow the spread of
acute EHV-1 infection amongst sufficient numbers of horses to allow the primary development of typical EHV-1 respiratory disease and some horses progressed to
develop typical EHV-1 neurological disease

We therefore wish to reinforce the advice already given by equestrian organisations that horses still remaining in Spain should only travel home when they have had sufficient time to demonstrate, in safe circumstances, that they have either not been infected or have fully recovered following infection. On return home, they should be isolated from other horses, tested for the presence of EHV-1 virus by swabbing and appropriately monitored for clinical signs of infection by their attending veterinary surgeon, before they are allowed direct or indirect contact with other equine animals.

Further relevant information concerning emerging virological findings will be reported

 

Attached is a document from LABEO with more details of the outbreak itself (from those who were involved with investigations and diagnostics at the event) and on-going genotyping of the virus, which, again, we hope will be of interest.  If members have any queries or questions on either of these attachments, do please contact us. 

 

Labeo Notice Valencia EHV-1 strain genotype.pdf