The Purpose Of Vaccination Equine Influenza

in Horse
Equine influenza (Horse flu) is the disease caused by strains of Influenza A that are enzootic in horse species. Equine influenza occurs globally, and is caused by two main strains of virus, equine-1 (H7N7) and equine-2 (H3N8). The disease has a nearly 100% infection rate in an unvaccinated horse population with no prior exposure to the virus.

While equine influenza is historically not known to affect humans, the impact of an outbreak would have been devastating. Since people heavily relied upon horses for communication (postal service), military (cavalry) and general transport, the social and economic impact of widespread equine disease would have been devastating. However, in modern times the ramifications of equine influenza are most clear in the modern racing industry.

Equine influenza is characterized by a very high rate of transmission among horses, and has a relatively short incubation time of 1-5 days. Horses with horse flu can run a fever, have a dry hacking cough, have a runny nose, and become depressed and reluctant to eat or drink for several days, but they usually recover in 2 to 3 weeks.

Equine influenza is caused by several strains of the Influenza A virus endemic to horses. Viruses that cause equine influenza were first isolated in 1956. The viruses can cross the species-barrier to cause an epizootic disease in humans, and recently, in dogs. The equine-1 virus affects heart muscle, while the equine-2 virus is much more severe and systemic. The disease is primarily spread between infected horses. Exposure to infected waste materials (urine and manure) in stables leads to rapid spread of the disease.

The report notes putative cases dating as far back as Hippocrates and Livius. Absyrtus, a Greek veterinarian from 330 CE, described a disease in the horse population having the general characters of influenza, which the report mentions as the earliest clear record of equine influenza in the lower animals.

The report notes the next recorded equine influenza case in 1299, the same year that a catarrhal epidemic affected Europe. Spanish records note cases in which "The horse carried his head drooping, would eat nothing, ran from the eyes, and there was hurried beating of the flanks. The malady was epidemic, and in that year one thousand horses died." Prevalence of influenza is found in historic records in the centuries of the Middle Ages, but direct implication of horses is not always clear. Neither are recorded instances of record deaths among horses and other animals clear on the exact cause of death.

The continent/country of Australia had remained free of equine influenza until an outbreak in August 2007. While the virus was successfully contained and Australia has returned to its equine influenza-free status, the outbreak had significant effects to the country's racing industry. Prevention of equine influenza outbreaks are maintained through vaccines and hygiene procedures. Countries that are equine influenza-free will normally impose strict and rigorous quarantine measures.

Vaccines are a major defence against the disease. Vaccination schedules generally require a primary course of vaccines, followed by booster shots. Standard schedules may not maintain absolutely foolproof levels of protection and more frequent administration is advised in high-risk situations. The UK requires that horses participating in show events be vaccinated against equine flu, and a vaccination card must be produced; the FEI requires vaccination every 6 months.
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This article was published on 2011/04/21