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Equine infectious anemia or equine infectious anaemia (EIA), also known by horsemen as swamp fever, is a horse disease caused by a retrovirus and transmitted by bloodsucking insects. The virus (''EIAV'') is endemic in the Americas, parts of Europe, the Middle and Far East, Russia, and South Africa. The virus is a lentivirus, like human immunodeficiency virus (HIV). Like HIV, EIA can be transmitted through blood, milk, and body secretions. Transmission is primarily through biting flies, such as the horse-fly and deer-fly. The virus survives up to 4 hours in the carrier. Contaminated surgical equipment and recycled needles and syringes, and bits〔(Equine Infectious Anemia (EIA) ), ''North Carolina Department of Agriculture and Consumer Services'', retrieved December 19, 2008.〕 can transmit the disease. Mares can transmit the disease to their foals via the placenta. The risk of transmitting the disease is greatest when an infected horse is ill, as the blood levels of the virus are then highest. ==Stages== Acute: The acute form is a sudden onset of the disease at full-force. Symptoms include high fever, anemia (due to the breakdown of red blood cells), weakness, swelling of the lower abdomen and legs, weak pulse, and irregular heartbeat. The horse may die suddenly. Subacute: A slower, less severe progression of the disease. Symptoms include recurrent fever, weight loss, an enlarged spleen (felt during a rectal examination), anemia, and swelling of the lower chest, abdominal wall, penile sheath, scrotum, and legs. Chronic: Horse tires easily and is unsuitable for work. May have a recurrent fever and anemia, may relapse to the subacute or acute form even several years after the original attack. There are currently no statistics available on mortality of EIA. No statistics are available of horses actually dying of acute forms. See also〔(A Horse, Of Course - Don Blazer ) at www.donblazer.com〕 A horse may also not appear to have any symptoms, yet still tests positive for EIA antibodies. This horse can still pass on the disease. According to most veterinarians, horses diagnosed EIA positive are usually not showing any sign of sickness or disease. EIA may cause abortion in pregnant mares. This may occur at any time during the pregnancy if there is a relapse when the virus enters the blood. Most infected mares will abort, however some give birth to healthy foals. Foals are not necessarily infected. Studies indicate that there are breeds with a tolerance to EIA.〔("Agricultural Biological Diversity" ), ''Convention on Biological Diversity'', referenced August 12, 2008.〕 Recent studies in Brazil on living wild horses have shown that in the Pantanal, about 30% of domesticated and about 5.5% of the wild horses are chronically infected with EIA. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「equine infectious anemia」の詳細全文を読む スポンサード リンク
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