2003 Equine Disease Outbreaks

According to the October issue of Equine Disease Quarterly (funded by underwriters at Lloyd's, London, brokers, and their Kentucky agents), a significant increase in the number of equine cases of Eastern equine encephalitis (EEE) was reported in the United States during June compared to numbers in recent years. The number of equine cases of West Nile virus (WNV) reported by the USDA as of Sept. 5 was 1,193, with Colorado, New Mexico, and Wyoming each reporting more than 100 cases. Only two states, Oregon and Nevada, are currently recognized as completely free of WNV. (The International Collating Centre, Newmarket, and other sources reported these disease outbreaks.)

Equine-confirmed or probable cases of WNV have been reported in five provinces of Canada--Alberta, Manitoba, Ontario, Quebec, and Saskatchewan.

Twelve abortions attributable to equine herpes virus (EHV-1) based on serological diagnosis were reported on six farms in Japan. Respiratory disease caused by EHV-4 was diagnosed among several different breeds of horses in France. Coital exanthema (EHV-3) was confirmed in a Thoroughbred stallion, and three mares showed clinical signs in Wales.

Equine influenza was reported from Denmark, France, and on three racetracks in Italy--Milan, Rome, and Turin. In the United Kingdom many racing stables in the Newmarket area were diagnosed with influenza as well as numerous other equine premises in England and Scotland. Among vaccinated horses, particularly those in Newmarket, the clinical signs were mild, including a cough at exercise and some horses with nasal discharge but little evidence of fever. Among non-vaccinated horses in the rest of England, the signs were more severe, including fever, a mucopurulent discharge, and frequent coughing at rest. Laboratory findings indicated the influenza virus causing the outbreak virus was closely related to an American lineage H3N8 virus isolated in Kentucky in 2002.

In the 2003 breeding season there was a dramatic reduction in the number of cases of Mare Reproductive Loss Syndrome (MRLS) in Central Kentucky compared to 2001 and 2002, with less than 10 reproductive and no eye or heart cases. Outbreaks of strangles were reported in Ireland, Switzerland, and the United Kingdom.


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Equine Disease Quarterly

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