Israeli Outbreak Mystery Revealed
Recently, I wrote about a large disease outbreak involving horses in Israel that resulted in a country-wide quarantine. Equine viral arteritis (EVA) has now been identified as the cause of the outbreak. This viral disease can cause a wide range of clinical signs in horses. It is often associated with abortion, but flu-like disease is common in adult horses, and is consistent with what was reported in Israel. The EVA virus is spread mainly by the respiratory route - contact with infectious nasal discharge is a prime means of transmission between horses.
It is currently unclear where the Israeli outbreak originated, or how it was propagated. Transportation of horses to shows, races and other events with subsequent mixing of horses is a great way to rapidly spread such a virus over a large area. The World Organization for Animal Health (OIE) reports that this virus has never been identified in Israel before. If this is indeed true, it could explain why the outbreak was so rapid and widespread - when a virus encounters a population of horses who don't have any immunity because they have not been exposed or vaccinated, more animals are likely to become sick and spread the virus further. The massive influenza outbreak in Australia last year was a great example of that.
It will be interesting to see what happens with this outbreak. The implementation of a nationwide quarantine, while certainly disruptive to many people, may have been an important step in limiting further transmission of the virus. A vaccine for EVA (which cannot be used in pregnant mares) is available, and could be used as part of outbreak control. However, good infection control practices are more important - vaccination will not be effective if it is the only measure taken.
Click here for more information on equine viral arteritis (EVA).
