This is a group of parasitic diseases caused by a protozoa under genus Leishmania, and is transmitted by several phlebotomine sandflies. The manifestations may be visceral, mucocutaneous, and cutaneous, and strain of the infecting organism and the immunologic reaction of the hosts apparently can greatly modify the clinical manifestations.

Kala-azar also known as Dumdum fever, and visceral leishmaniasis occurs in India, China, Russia, Africa, the Mediterranean basin, and several South and Central American countries. Children and young adults are particularly susceptible. The protozoa Leishmania donovani invade the bloodstream and localize in the reticuloendothelial system, causing fever, pronounced splenomegaly, emaciation, and pancytopenia. The fever is seldom sustained and recurs irregularly. The liver and the lymph nodes may become enlarged and hypergammagloblulinemia is present. The parasite may be demonstrated in needle biopsy of the liver, spleen, bone marrow, lymph nodes, blood or in cultures of these tissues. Sensitive serologic tests have been developed but are not generally available. The leishmania skin test is negative during the active phase of the disease. The fatality rate is 90% in untreated cases but generally below 10% in treated cases.

Treatment consists of bed rest, good nutrition, oral hygiene, and blood transfusion is given for severe anemia. Antibacterial therapy is given for complications. Pentavalent antimony compounds and aromatic dimidines are the drugs of choice. Sodium antimony gluconate is given once daily, by slow intravenous route or intramuscularly. The dosage is 10 mg/kg/injection or a maximum of 600 mg antimony/day. If toxic effects are noticed like nausea and vomiting, the drug should be given every other day, or the dose is reduced.

Kala-azar encountered in Sudan is resistant to antimony, hence, pentamidine is used at a dosage of 4 mg/kg/day intramuscularly for up to 15 days.

Babesiosis- is a cosmopolitan infection of animals caused by intraerythrocytic parasites of the genus Babesia. Human disease is rare. The organisms are transmitted by hard-bodied ticks and produce a febrile hemolytic anemia. In splenectomized patients the infection has a high mortality rate and closely resembles falciparum malaria, with high fever, hemolytic anemia, hemoglobinuria, jaundice, and renal failure. A patient with an intact spleen has a milder illness that usually resolves spontaneously in weeks or months. Most cases in the USA have been of this milder type and have been acquired on offshore islands of New York and Massachusetts.

Diagnosis of this disease requires demonstration of the parasites which resemble those of malaria in Giemsa stained smears of peripheral blood. In contrast to Plasmodium species, no gametocytes or malarial pigments can be seen. The presence of tetrads and basket-shaped parasites is also helpful.

Treatment consists of bed rest, good nutrition and antibiotics or antibacterials for complications. In life-threatening cases, pentamidine or diminazene aceturate appear to be effective.

Onchocerciasis also called River blindness is a disease caused by Onchocerca volvulus and characterized by fibrous nodules in the skin and subcutaneous tissues. Ocular findings are common and blindness may result. The disease, spread by the bite of black flies occurs in southern Mexico, Guatemala, Venezuela, Colombia, Yemen, and central Africa.

Diagnosis depends on the demonstration of the parasites or microfilariae in the skin or lymph nodes of the patients. Treatment-diethylcarbamazine given orally after meals. Since an allergic reaction to the dead microfilariae can result in ocular damage if the eye is involved, the dosage is limited to 0.1 top 0.2 mg/kg/day, eventually increased to 2 to 3 mg/kg three times a day and then maintain at this level for one week. An antihistamine or prednisone may be given for the allergic reactions.