Leishmaniosis is a chronic, serious disease that affects people, dogs, and some other mammals. It is caused by Leishmania protozoal parasites. In dogs, the disease affects both the skin and internal organs.
Canine leishmaniosis is common in Central and South America, the Middle East, Asia, and the Mediterranean region. It also occurs occasionally in North America, especially in Foxhounds, and in dogs that have traveled to affected regions.
The disease can be spread from dogs to people. Most infections in people occur when a person is bitten by a sand fly that has previously bitten an infected animal or person. While human cases are rare in the United States, there are hundreds of thousands of cases worldwide each year, with tens of thousands of deaths.
In affected dogs, the incubation period (time from initial infection to the onset of signs) can range from months to several years.
Signs vary widely and include skin lesions, weight loss, decreased ability to exercise, lack of energy, poor appetite, enlarged lymph nodes, eye disease, kidney failure, nosebleeds, lameness, and anemia (low red blood cell count). Some dogs also develop chronic diarrhea or liver disease. Skin signs often include hair loss and severe scaliness (usually starting on the head and spreading across the body) or chronic sores on the head and legs, sometimes with bleeding from ear lesions. The disease typically progresses slowly.
Diagnosis is based on specialized blood tests that detect either the parasite or the immune response to it. Finding the parasite directly can be difficult.
Treatment is available but usually requires 6–12 months or longer. It often improves signs but does not eliminate the infection completely, so dogs may remain carriers of the parasite, and recurrence is common.
Prevention is important and includes using insecticides that repel sand flies, especially in areas where the disease is common or for traveling dogs. Control measures also include managing stray dog populations and decreasing sand fly exposure. Vaccines are available in some regions, including Europe and Brazil.
Because dogs can serve as a source of infection for people, especially children, prevention in dogs is also important for public health.
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