Equine Infectious Anemia in polo horses
Since the end of June, the notifiable animal disease Equine Infectious Anemia (EIA) has been detected in Germany in 11 polo horses from 7 holdings. Pursuant to the regulation for protection from EIA, horses which tested positive for the disease were culled. As prescribed by law the responsible local veterinary authorities initiated the ban and investigation of all affected holdings and contact holdings. Currently the federal states Hamburg, Lower Saxony, North Rhine-Westphalia, and Bavaria are affected. The Netherlands have also reported one case in a polo horse. Background of and possible associations between the currently increased case numbers in polo horses are being investigated.
EIA is distributed worldwide and occurs in increased numbers in Asia, Eastern Europe and South America. In Germany, the virus disease is detected sporadically in horses, i.e. individual outbreaks occur repeatedly. In the last few years, most cases have been associated with imported horses. Horses with acute infection can show fever, apathy, as well as petechiae particularly on the underside of the tongue, mucous membranes and lid conjunctiva.
Infected animals remain life-long carriers and are potential sources of infection. Despite of the name “anemia” given to this disease in many cases no anemia, which is caused by immunopathological lysis of red blood cells, is observed. In 30 to 90 percent of cases no visible symptoms of disease occur, the animals remain healthy appearing virus carriers.
The virus is mainly transmitted by large blood-sucking insects, such as horseflies and stable flies. Given the climatic conditions in Germany no epidemic spread is observed. Transmission of the disease is also possible through direct contact between horses (blood, small wounds) and iatrogenically (by medical treatment, in particular when one needle/syringe is used for several animals).