UPDATE ON AFRICAN HORSES SICKNESS

African horsesickness (AHS)is a fatal, febrile, seasonal, viral disease of horses. Mules, donkeys and zebras are also susceptible to infection. African horsesickness virus is an orbivirus classified along with bluetongue virus and epi­zootic hemorrhagic disease vi­rus within the family reoviri-dae.  The disease is transmit­ted amongst animals by biting midges (Culicoidessp.).  In­fection in naive populations of susceptible animals results in high morbidity and mortality. The disease in its acute (pul­monary) and subacute (cardiac) forms is characterized by accu­mulations of serous fluid with­in body cavities and marked edema,  congestion and hemor­rhage in several tissues. Most dramatic tissue involvement is observed in the lung, pleura and pericardium.

African horsesickness is prevalent in many countries of central and southern Africa. During the last forty years, the disease has spread to northern Africa, most countries of the Middle-East, Portugal and recently Spain.  The recent outbreaks in Spain from 1987-,1992 have resulted in dramatic losses in equids.  The outbreak in 1987 was believed to have resulted from the importation of infected zebras from Nambia, Africa.  Since then, AHS has reappeared annually in late summer and fall, killing hun­dreds of animals.  The Office of InternationaledesEpi-zooties and the International Equestrian Federation are work­ing together with animal health officials to render Barcelona Spain, the site of the 1992 Summer Olympic Games, free of AHS.  Control measures include widespread use of insecticides, limited animal movement between provinces, strict quarantine regulations, sacrifice of sus­pect animals and stabling of animals when insect vectors are most active.  Since the 1991 outbreak, Spain has been free of the disease.

Should AHS recur this summer in Spain, equids participating in the Olympic games are at an increased risk in contracting the disease.  Culicoides sp. native to the U.S. are proven competent vectors in transmitting AHS, hence the introduc­tion of a single viremic animal could result in rapid, wide­spread introduction of the dis­ease in the U.S.  The U.S. will impose a mandatory 60 day quar­antine period for all horses returning from equestrian events of the Olympic Games, thus ensuring the U.S. remains free of AHS.  Horses will be quarantined in Newburg, New York.  Definitive diagnosis of AHS is achieved through virus isolation, ELISA and CF tests performed at Plum Island Animal Disease Diagnostic Laboratory. Anthony SkowronekGraduate Student of ADDL