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Animal Health Trust |
Interim Report – May 2011 #3 (19.05.11)
UNITED STATES OF AMERICA
Equine Herpesvirus-1(EHV-1) Neurological Disease
Within the past week, cases/outbreaks of equine herpesvirus-1 neurological disease or myeloencephalopathy (EHM) have been reported from a number of Western states in the US. Outbreaks of neurological disease, presumed though not in the majority of instances yet confirmed to be EHM, have been reported in California, Colorado, Idaho, Utah, Nevada, Washington State, New Mexico, Arizona, and Oregon. It is known that at least 7 severely affected horses have been euthanased. Based on initial epidemiological investigation, there is a history of affected horses having attended the National Cutting Horse Association’s Western National Championships in Ogden, Utah, that was held between April 28th and May 8th 2011, where it would appear spread of EHV-1 took place.
Many of the horses that competed at the National Championships in Ogden subsequently competed at a Cutting Horse show in Bakersfield, California where several animals became ill during that event. At this time, while the number of affected states involved in the current disease event has not been fully determined, reports of clinical cases of neurological disease have only come from Western states in the US. It should also be emphasised that the cases of neurological disease have so far been restricted to Quarterhorses. There is very little evidence that horses from states east of the Mississippi River competed in the Cutting Horse events at Ogden or Bakersfield. At this time, the number of cases of confirmed EHM though limited, is increasing. At least 11 equine EHV-1 isolates are of a neuropathogenic genotype.
At the request of the American Horse Council and the American Association of Equine Practitioners, the USDA, APHIS, VS has assumed responsibility for obtaining, compiling and disseminating information on numbers of outbreaks and cases of confirmed/suspect EHM from all states. It is expected more definitive information on the geographic extent of this disease event will be available very shortly. In view of the seriousness of the current disease situation, various Cutting Horse events/shows have been canceled for the time being in an effort to restrict the risk of possible further spread of the infection.
Regards
International Collating Centre