Recent advances in the diagnosis of leishmaniasis

Leishmaniasis is a parasitic disease caused by a haemoflagellate Leishmania. There are more than 21 species causing human infection. The infection is transmitted to humans through the bites of female sandflies belonging to 30 species. The disease manifests mainly in 3 forms: the visceral, the cutaneous and the mucocutaneous leishmaniasis. The diagnosis of visceral form is conventionally made by the demonstration of amastigotes of the parasite in the aspirated fluid from the bone marrow, the spleen, and rarely from the lymph nodes, or the liver. The parasite demonstration and isolation rates are rather poor from cutaneous and mucocutaneous lesions due to low parasite load and high rate of culture contamination. Recently several recombinant proteins have been developed to accomplish accurate diagnosis. Recombinant kinesin protein of 39 kDa called rK 39 is the most promising of these molecules. The antigen used in various test formats has been proved highly sensitive and specific for visceral leishmaniasis. It is useful in the diagnosis of HIV-Leishmania co-infection and as a prognostic marker. Molecular techniques targeting various genes of the parasite have also been reported, the PCR being the most common molecular technique successfully used for diagnosis and for differentiation of species.