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 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.