International Equine Disease Report Third Quarter 2007

This is an excerpt from Equine Disease Quarterly, funded by underwriters at Lloyd's, London, brokers, and their Kentucky agents.

The International Collating Centre, Newmarket, England, and other sources reported the following disease outbreaks.

The United States Department of Agriculture (USDA), as of October 30, reported on the Equine Health Monitoring and Surveillance Web site 130 cases of Eastern equine encephalitis (EEE) during 2007, the majority occurring in the southern states of Mississippi (30), Florida (17), Louisiana (38), and Texas (19).

A single case of West Nile virus (WNV) infection was reported from the United Arab Emirates in a non-Thoroughbred horse that recovered. The USDA reported 407 equine cases of WNV during 2007 up to November 6, widely distributed throughout the USA. The highest numbers of WNV cases were in Texas (59), Montana (32), California (28), and Colorado (29). By comparison, 1,086 equine cases were reported in the USA in 2006. As of November 6, the Centers for Disease Control reported 3,265 human cases for 2007, with 92 fatalities.

Cases of equine herpesvirus (EHV) respiratory disease were widely reported among a variety of breeds in France. In the United Kingdom, respiratory disease attributable to EHV-1 was diagnosed among a group of donkeys and to EHV-4 among a group of foals. Cases of EHV-1 abortion were diagnosed in June on three premises in the Western and Eastern Cape Provinces of South Africa. The neurological form of EHV-1 was confirmed among six horses on a single premise and coital exanthema (EHV-3) on two premises in the United Kingdom.

Equine infectious anemia (EIA) was identified during August in a horse imported from Romania to central Germany, and during September in a 12-year-old saddle mare that died in Ardeche, France.

Further details have been provided regarding the outbreak of Equine Viral Arteritis (EVA) in France. The outbreak, occurring between May and September, originated with a Percheron stallion shedding the virus in the semen and other stallions at the Haras du Pin National Stud. Cases were subsequently diagnosed on 28 premises in five different areas. Several hundred mares and foals, mainly draught and saddle horses, were found to be seropositive. Five foals died and several mares aborted. Thoroughbreds were not affected. Equine arteritis virus was transmitted following artificial insemination and natural mating. Symptoms in mares were mild or subclinical, with foals developing acute signs including fever, respiratory signs, and edema of the sheath and limbs.

The outbreak of equine influenza in Australia, which began in mid-August, remains confined to New South Wales and Queensland. It originated in the Sydney quarantine facility that housed imported shuttle stallions, with escape of virus resulting in widespread infection of the indigenous, naive population. As of November 26, 5,391 infected premises are in New South Wales and 2,166 in Queensland. In place are zoning, movement restrictions, biosecurity, and influenza vaccinations in buffer zones and of strategic horse populations. High value horses, generally Thoroughbred racehorses, are being vaccinated in New South Wales, Queensland, and Victoria. Vaccination has been initiated using a live recombinant vaccine produced by Merial.

The extensive outbreak of influenza in Japan first diagnosed at the Miho Training Center of the Japan Racing Association (JRA) on August 15 has continued, but with a decreased rate of occurrence. This is the first outbreak of influenza in Japan since 1972, and it has affected Thoroughbreds, non-Thoroughbreds, and pleasure horses throughout the country. Thoroughbred racehorses are routinely vaccinated twice a year, having received their last vaccination in May 2007 with a Japanese-manufactured killed vaccine. Following confirmation of the outbreak, movement restrictions were imposed. Six race meetings scheduled for August 18 and 19 at Sapporo, Niigata, and Kokura were cancelled. Racing resumed on August 25 under strict veterinary supervision. On September 4 the ban on the movement of horses between JRA and non-JRA facilities was partially lifted. Equine influenza was also confirmed on eight premises in Ireland.

Twenty-five cases of Potomac horse fever (PHF) were reported between June and August in Kentucky and Ohio by the University of Kentucky Livestock Disease Diagnostic Center, Lexington. The majority of cases were identified and treated by equine practitioners in the early stages of disease, resulting in low mortality.

Clinical cases of equine piroplasmosis were reported from South Africa, Switzerland, and Turkey. Turkey also reported a single case of equine rabies during July. Rotavirus infection was confirmed on five premises in Ireland.

Strangles was reported from Denmark, on two premises involving numerous horses; from Ireland, 14 premises with 19 cases; from South Africa, at least 50 horses on five premises in the Western Cape and Gauteng provinces; and Switzerland, involving animals on three premises.

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Equine Disease Quarterly

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