Abstract

PIP: 2 large epidemics of visceral leishmaniasis are presently occurring in Bihar State, India and in southern Sudan where it had not previously been a problem. Civil war which in turn led to sizable malnutrition and migration of many people and animals contributed greatly to the present epidemic. In southern Sudan, 30,000-40,000 people have already died. Villages have lost 30=65% of their population to visceral leishmaniasis, 4-40% carry the parasites, and 30-40% are immune to it. The epidemic is extending to the north. Other endemic areas in Africa include Kenya, many western and central African countries, and all the countries in northern Africa. Animal hosts include rats, genets, several cats, jackals, and dogs. The protozoan parasites Leishmania species are becoming more and more resistant to drugs which exacerbates these epidemics. The treatments include pentavalent antimonials, aminosidine, pentamidine, amphotericin B, liposomal amphotericin B, and sodium stibogluconate. The sandfly vector in India is beginning to exhibit resistance to DDT, but this is not yet a problem in Africa, however. The sandfly transmits promastigotes into the skin where an inflammatory factor in the sandfly saliva strengthens infectivity. They then infect phagocytic cells, especially macrophages, which essentially suppresses immunity. There they transform into amastigotes. Even though the body has very high levels of antileishmanial antibodies, the macrophages cannot eliminate the intracellular amastigotes. The parasites invade the spleen, liver, bone marrow, and lymph nodes--the macrophage-rich organs--which causes clinical symptoms. Some of these clinical symptoms include fever, wasting, splenomegaly, bone marrow failure, and lower than normal amounts of all cellular elements of blood. In HIV-positive Europeans who have lived in or visited endemic areas, visceral leishmaniasis has become an opportunistic infection. Their atypical features make it important to look for the parasites in tissues to diagnose it.