Leishmaniasis

Abstract

Leishmaniases are diseases caused by several species of Leishmania protozoa and occur in all continents, except Antarctica. Almost 20 species have been isolated from humans, and they may cause cutaneous, mucocutaneous, and visceral forms of the disease. The severity of the infection depends on the protozoon species and strain, host immune response, nutritional status, and, to a lesser extent, sand fly species involved in the transmission. Depending on the parasite tropism, amastigotes invade macrophages in the skin, mucosa, and internal organs, mostly the spleen, liver, and bone marrow, causing their depletion. Clinical presentations may vary from localized skin lesions to generalized disease, with fever, weight loss, enlargement of the spleen and liver, anemia, leucopenia, and thrombocytopenia. Transmission primarily occurs by the bites of sand flies, the only proven biological vectors of Leishmania parasites. Secondary transmission routes have been demonstrated in both humans and dogs, including congenital transmission. The epidemiology of leishmaniases is complex, as it involves different vector, host, and parasite species, living in a constantly changing environment. Disease diagnosis and treatment are still complicated, particularly in developing countries. More effective control strategies are urgently needed to reduce the burden of leishmaniases in endemic areas. Meanwhile, education and better living conditions for people residing in risk areas are key to controlling this group of diseases.