Leishmaniasis

The parasite, Leishmania, and its vector, the phlebotomine sand fly, are found in tropical and subtropical regions of every continent except Australia and Antarctica; the incidence of the disease seems to be increasing, especially in the New World, as forest clearing, resettlements, and water resource development increase contact with the vector. The disease takes three forms in humans: a visceral form -- the most dangerous -- which infects the spleen, liver, and bone marrow; a mucosal form, which invades and often destroys the mouth, nose, and throat; and a cutaneous form, which is usually self-healing but is characterized by disfiguring skin lesions. Diagnosis and treatment depend on the form being treated. Chemotherapy commonly uses pentavalent antimonials, especially for visceral leishmaniasis. Vaccination has been successful only against cutaneous leishmaniasis. Household spraying with residual insecticides has been the most effective vector control measure. Successful control programs have integrated chemotherapy, vector control, vaccination, and elimination of animal reservoirs; unfortunately, due to economic constraints in developing countries, leishmaniasis is given low priority until an outbreak occurs. Research priorities include developing improved chemotherapies (e.g., eflornithine), antigens, and vaccines, and conducting operations research on alternatives to chemical control of the vector.