In early August 2007, five breeding stallions from Japan were admitted to a quarantine facility in New South Wales, Australia. Before long, horses at the facility began running high fevers and showing respiratory disease. The disease was confirmed to be equine influenza. Somehow, it escaped the quarantine and sick horses were showing up at barns and racetracks. What followed was a nightmare that cost the equine industry over $100 million.
Australia had previously been free of equine influenza. As a result, none of the horses had any immunity to it, and none had been vaccinated. Because of how highly infectious flu is, and because it can spread both by horse contact and contact with contaminated tools, clothing, etc. , the infection spread rapidly. It eventually made its way into Queensland.
The authorities sprung to action quickly. Unlike with West Nile and the American government, they had two things in their favor: 1) Because the disease was spread directly by horses, not insects, it would be easier to control the spread, and 2) Flu vaccine was available from other countries.
The decision was made to design a program that would eradicate the disease. As an initial step, all movement of horses came to an immediate halt. Red (infected), yellow (exposed or recovering) and green (no apparent disease) zones were established. The vaccine was used sparingly and only to establish buffer zones to help control further spread of the virus. Restricted vaccine use initially angered many owners, but it was necessary to allow authorities to identify truly infected horses versus horses with a vaccine titer, and the ultimate goal of eradicating the disease was in everyone’s long-term best interest.
The measures worked. As the disease came under control, strictly regulated and limited movement of some horses was allowed, which helped ease the blow on the breeding industry. By February 28, 2008, New South Wales was declared influenza-free. On March 14, Queensland was similarly declared disease-free. By World Health Organization standards, Australia will be required to monitor for another year before being granted official equine influenza-free status.
The Australian experience, like the one with West Nile in the United States, is a sobering reminder to both owners and health professionals that the shrinking world comes with an infectious-disease-risk price tag.
There’s no need for paranoia, but horses with unexplained fever or unusual symptoms, and outbreaks of infectious disease, should always be brought to the attention of your veterinarian promptly. If there is any question as to the cause, the state veterinarian should be involved.