Equine Disease Outbreaks | April report

The College of Agriculture, Food and Environment in Lexington, Kentucky is home to the Gluck Equine Research Center, which, according to its website, is the only scientific institute in the United States with nearly all faculty conducting full-time research in equine health and diseases. Its Department of Veterinary Science publishes Equine Disease Quarterly, a newsletter that features a breakdown of the past quarter’s international disease outbreaks. 

We will be keeping you apprised of equine disease outbreaks around the world by publishing the department’s quarterly report right here on our blog every January, April, July and October.



The International Collating Centre, Newmarket, United Kingdom, and other sources reported the following equine disease outbreaks. 

The Republic of South Africa (RSA) reported sporadic cases of  African horse sickness in Free State, Gauteng, and North West Province. These represented the first cases recorded in the 2019/2020 season. 

Three separate outbreaks of glanders were confirmed in Turkey. These were associated with illegal movement of horses without identification or veterinary certification. Of 1,375 horses tested, 63 were positive and 18 suspect; all were euthanized. 

Equine influenza was confirmed in France, Germany, the Netherlands, the UK, and the USA. With the exception of the USA, the number of outbreaks ranged from 1-3, the majority in unvaccinated horses. The disease is endemic in the USA, with outbreaks diagnosed in seven states and multiple outbreaks in one state. 

Belgium, France, Germany, the Netherlands, Switzerland, and the USA recorded strangles. The number of outbreaks varied from four (Belgium), 21 (France), three (Germany), 12 (the Netherlands), one (Switzerland) to 40 in the USA, where the disease is endemic. 

Equine herpesvirus 1 (EHV-1) related diseases were recorded by Belgium, Canada, France, Germany, the Netherlands, RSA, UK, and the USA. 

 Respiratory disease outbreaks were diagnosed in France (two), the Netherlands (one), RSA (one), UK (four), and in several states in the USA. 

EHV-1 abortion was reported by France (one case) and the Netherlands (one case). EHV-1 neurologic disease was confirmed in Belgium (one outbreak involving five horses), Canada (two cases), France (two outbreaks), Germany (one case), the Netherlands (three outbreaks, one involving 11 affected horses and the other two, single cases), and the USA (17 outbreaks in 10 states, one involving eight cases and the remainder, single cases). 

Equine herpesvirus 4 respiratory disease outbreaks were reported by France (41, the majority involving single cases), Germany (three, all single cases), Japan (one outbreak involving two horses), the Netherlands (five, involving one to five animals apiece), and the UK (11). While the majority were represented by single cases, one outbreak involved 32 weanlings and another eight yearlings. France (two outbreaks) and the USA (three outbreaks) reported single cases of EHV-4 abortion. 

Numerous cases of EHV-2 and EHV-5 infection were confirmed by the USA, a percentage of which were associated with clinical respiratory disease. 

France and the USA reported two outbreaks of Equine infectious anemia apiece. Each involved a single case. 

Only a single report of equine piroplasmosis was received in the fourth quarter of 2019. The RSA reported that the disease was endemic throughout the country. 

A total of 19 cases of nocardioform placentitis and abortion were diagnosed in Kentucky, USA during the period under review. A range of bacterial organisms were identified with cases of the disease. 

Contagious equine metritis was reported by several countries. Denmark, France and Germany each detected Taylorella equigenitalis in a stallion. South Korea recorded three positive animals out of 2,269 samples tested, the gender of the animals was not identified. Other causes of abortion reported by Kentucky, USA included Neorickettsia risticii (two cases). 

The USA recorded one case of Salmonella infection in Kentucky; several cases of rotavirus infection in three states, two involving strains of the G3 genotype and four the G14 genotype; nine cases of Lawsonia enteropathy; and 10 cases of infection with Clostridium perfringens Toxin A genotype. 

Eastern equine encephalomyelitis (EEE) was reported by the USA, with 30 cases diagnosed in the fourth quarter, 10 in Michigan and nine in Indiana. The majority were in unvaccinated horses that died or were euthanized. 

France, Germany, Portugal, and the USA confirmed cases of West Nile (WN) encephalitis . Outbreaks in France (seven), Germany (three), and Portugal (one) involved one or two cases. A total of 25 cases were recorded in the USA, of which 10 were in Colorado and six in Florida. One case was positive for both EEE virus and WN virus. 

The RSA confirmed one case of equine encephalosis, and the USA diagnosed three cases of equine protozoal myelitis during the period under review. 

The fourth quarter saw an additional 35 outbreaks of Vesicular stomatitis reported by the USA on premises in eight states. No new affected premises have been identified since late November. 

The USA confirmed two outbreaks of Rhodococcus equi infection, but this significantly underrepresents the incidence of this endemic disease in the country.

This content was originally published in Equine Disease Quarterly, funded by underwriters at Lloyd’s, London. We have edited formatting and added links to provide further information on the diseases mentioned. 

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