Equine influenza

Influenza (Flu)
Types
Avian A/H5N1 subtype Canine Equine Swine A/H1N1 subtype
Vaccines
2009 pandemic Pandemrix Fluzone Influvac Live attenuated Optaflu
Treatment
Amantadine Arbidol Laninamivir Oseltamivir Peramivir Rimantadine Vitamin D Zanamivir
Pandemics
2009 swine 1968–1969 Hong Kong 1957 Asian flu 1918
Outbreaks
2008 West Bengal 2007 Bernard Matthews H5N1 2007 Australian equine 2006 H5N1 India 1976 swine flu
See also
Flu season Influenza evolution Influenza research Influenza-like illness Vaccine reformulations

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).^{[citation needed]} The disease has a nearly 100% infection rate in an unvaccinated horse population with no prior exposure to the virus.^{[citation needed]}

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. In modern times, though, the ramifications of equine influenza are most clear in the modern horse racing industry.

Characteristics

Equine influenza is characterized by a very high rate of transmission among horses, and has a relatively short incubation time of one to five days.^{[citation needed]}

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 two to three weeks.

An 1872 report on equine influenza describes the disease as:

"An epizootic specific fever of a very debilitating type, with inflammation of the respiratory mucous membrane, and less frequently of other organs, having an average duration of ten to fifteen days, and not conferring immunity from a second attack in subsequent epizootics."

— James Law, Report of the Commissioner of Agriculture for the year 1872

Causes

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,^{[citation needed]} while the equine-2 virus is much more severe and systemic.^{[citation needed]}

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.

History

A comprehensive report describing the disease - compiled in response to the 1872 outbreak of the disease in North America - provided a thorough examination of the history of the disease.

Early records

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 noted 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.

1872 American outbreak

An epizootic outbreak of equine influenza during 1872 in North America became known as "The Great Epizootic of 1872". The outbreak is known as the "most destructive recorded episode of equine influenza in history". During the late 19th century, the United States still depended heavily on the use of horse power to survive - in much the same way that most of the world depends on gasoline now. Horses were responsible for unloading cargo at ports, transporting goods between cities, working farms, and were also relied upon for use as emergency vehicles in times of need. When horses became unable to perform these functions due to the spread of the disease, America suffered - and its economy came nearly to a halt. In fact, the Great Epizootic of 1872 had such a dramatic effect on the United States that it is labeled to be one of the major contributors to the Panic of 1873, an economic crash that took a full 6 years to remedy.

The first cases of disease in pasture horses were in the townships of Scarborough, York, and Markham in Ontario, Canada. By October 1, 1872, the first case occurred in Toronto. It took only three days before all the street car horses and major livery stables were affected. By the middle of the month, Montreal, Detroit, and most of the Dominion of Canada and New England reported cases. On October 25, 1872, The New York Times reported on the extent of the outbreak, claiming that nearly all public stables in e city had been affected, and that the majority of the hoses owned in the private sector had essentially been rendered useless to their owners. Only days later, the Times went on to report that 95% of all horses in Rochester, New York, had been affected, while the disease was also making its way quickly through the state of Maine and had already affected all fire horses in the city of Providence, Rhode Island

On October 30th, 1872, The New York Times reported that a complete suspension of travel had been noted in the state. The same report also took note of massive freight backups being caused by the lack of transportation ability that was arising as a result of the outbreak. In fact, reports began to come in around this time of massive market failures due to the lack of horse-power to move goods from one place to another. Cities like Buffalo and New York were left without effective ways to move merchandise through the streets, and even the Erie Canal was left with boats full of goods idling in its waters, unable to have their products taken to market without the horses there to unload the stock. By the start of November, Ohio, Massachusetts, and South Carolina were reporting cases. So was Chicago, Illinois. The contagion reached Florida and Louisiana by the end of November and Cuba on December 7. The height of the plague was December 14, when the Mexican government had to supply disease-free horses to the stricken United States. One major factor was lack of modern municipal sanitation, which meant that germs spread much more quickly (especially through contaminated feed and water).

The rate of infected horses approached 100%, and mortality rates ranged between 1% and 10%. Many horses were unable to stand in their stalls. Those that could stand coughed violently and were too weak to pull any loads or support riders.

The street railway industry ground to a halt in late 1872. Every aspect of American transportation was affected. Locomotives came to a halt as coal could not be delivered to power them. Without coal to power locomotives, the railroad industry was hit by an economic shock that could not have been predicted. The effects of the horse shortage were so prevalent in this industry that reports indicate that the interruption in business that resulted from the horse shortage sent nearly one third of all railroad enterprise into bankruptcy. With railroads unable to function, goods unable to move, and markets failing across the nation, the American economy was hit hard by the outbreak of the equine influenza in 1872. Thousands of firms across the nation began to spiral downward – many of them never managing to pull back up and going completely out of business.

Industry aside, one of the greatest casualties of the Great Epizootic was the city of Boston. In a time when fire engines were still drawn by horses - the Boston Fire department did not purchase its first motorized fire engine until the year 1911 – the outbreak of a great fire in the heart of the city on November 9th was a disaster. Firemen were reduced to moving all of the necessary firefighting equipment by hand, and the size of the fire in this particularly incident did not allow for such slow movement to be effective. The firefighting sans horse power was so ineffective that the fire raged on to become one of the worst disasters in the history of the city. Reports indicate that the blaze killed 13 people, destroyed 776 buildings, and caused $75million in damages – the current equivalent of roughly $3.5billion. Indeed, many a fireman just stood there helpless and horror-stricken, for lack of any equipment with which to work. Even the United States Army Cavalry was reduced to fighting on foot against the Apaches (as the plague had swept not only south to Mexico and Cuba, but also west to the Pacific Ocean within two months), who likewise found their mounts too sick to do battle. The outbreak forced men to pull wagons by hand; while trains and ships full of cargo sat unloaded (perishables, such as milk, often became spoiled), tram cars stood idle and deliveries of basic community essentials (including food and clothing) were no longer being made. The Long Riders' Guild Academic Foundation founder CuChullaine O'Reilly said, "The Great Epizootic was the worst equestrian catastrophe in the history of the United States - and perhaps the world."

Essentially, the Epizootic caused failures in most markets of the US economy, and because technology was not advanced enough to sidestep the problem – cars would not find their way onto the scene for at least another decade with the invention made by Mr. Karl Benz – the economy was left without any effective plan or even a feasible course for recovery. The transportation and industrial power source of the entire society was disabled, and there was no stimulus that could have corrected the situation at that point; the epizootic of 1872 left the United States in a position similar to the one that it would be in if all oil were to disappear from the market today.

Ironically, the vast majority of affected horses – save for those 10% that died as a result – were back to full health by the following spring. The effects of the outbreak, however, would be felt by the economy for the majority of the next decade, as the Panic of 1873 wreaked havoc on the nation for 6 more years.

2007 Australian outbreak

Main article: 2007 Australian equine influenza outbreak

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 on the country's horse racing industry.

Prevention

Prevention of equine influenza outbreaks are maintained through vaccines and hygiene procedures.^{[citation needed]} Countries that are equine influenza-free will normally impose strict and rigorous quarantine measures.^{[citation needed]}

Vaccines

Vaccines (ATCvet codes: QI05AA01 inactivated, QI05AD02 live, plus various combinations) are a major defense 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 horses participating in show events be vaccinated against equine flu, and a vaccination card must be produced; the FEI requires vaccination every six months.

See also

• Avian influenza
• Canine influenza
• Human influenza

Sources and notes

• health24.com
• Equi Flu Net

External links

• EI Vaccination Debate - Australia equinetrader.co.nz
• COntrolling Equine Influenza - Japan equinetrader.co.nz
• Great Epizootic of 1872 equinetrader.co.nz
• Caring for a horse with equine influenza Horsetalk.co.nz (NZ)
• Equine flu resources: Q&A, latest news, contacts Horsetalk.co.nz (NZ)
• Veterinary Record
• Equine Quarterly Disease Surveillance Reports
• Horse Flu