Leishmaniosis (leishmaniasis) is a longterm, severe, protozoal (parasitic) disease of humans, dogs, and other animals. Dogs serve as the major source of the infection (the "reservoir host"), and cats are rarely infected. The single-celled parasite is transmitted through the bite of a sand fly that has previously bitten an infected animal or person. In people, it is mostly a disease of young children, especially those who are malnourished or have suppressed immune systems. The disease is potentially fatal in dogs and people. The disease is prevalent in Africa, Central and South America, the Middle East, Asia, and in the Mediterranean region. It occurs only occasionally in the United States.
In cats, the disease usually affects the skin but can also affect the internal organs. The most common skin lesions are areas of baldness with severe dry skin shedding, usually beginning on the head and extending to the rest of the body. Ulceration can also develop, particularly on the head and limbs. Ulcers on the ears can bleed considerably.
Laboratory tests are used to diagnose leishmaniosis. Drug treatment is available for dogs, but it usually does not eliminate the parasites. Treated dogs can remain carriers of the infection, allowing it to spread to others. Control of sand flies and topical insecticides are critical for dogs in areas where leishmaniasis is common. Because dogs can serve as a source of infection for people, preventing canine infections is important for human health in these areas.
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