Leishmania major: a very sensitive dot-blot ELISA for detection of parasites in cutaneous lesions.

There is a need for accurate, rapid and early diagnosis of leishmaniasis, which would distinguish between the benign and severe forms of the disease. We have used a monoclonal antibody directed to a polymorphic, species-specific antigen in diagnostic assays for leishmaniasis. The dot-blot enzyme-linked immunosorbent assay described here can detect as few as 300 culture promastigotes and 20,000 amastigotes of Leishmania major with no cross-reaction with other species and no background from skin macrophages or other cells. This level of sensitivity is sufficient to detect parasite antigen aspirated in a few microliters of liquid from small lesions in mice. This assay could form the basis for a sensitive, rapid and inexpensive dip-stick test for large-scale use for the diagnosis and epidemiology of cutaneous leishmaniasis.