An antigen (LMS) prepared from Leishmania major-like promastigotes was used in an enzyme-linked immunosorbent assay (ELISA) for the diagnosis of human and dog visceral leishmaniasis. The results were compared with those from the indirect immunofluorescent antibody test (IFAT). A total of 1,822 canine sera were tested, including sera from dogs with visceral leishmaniasis, transmissible venereal tumors, ehrlichiosis, rickettsiosis, or Chagas' disease and sera from healthy dogs. The antigen was also tested with 227 samples of human sera, including sera from patients with visceral, cutaneous, or diffuse cutaneous leishmaniasis and from noninfected individuals, as well as sera from patients with Chagas' disease, toxoplasmosis, rickettsiosis, hepatitis B, schistosomiasis, ascaridiasis, malaria, rheumatoid factor, leprosy and rheumatoid factor, tuberculosis, or leprosy. All dogs and all human patients had a clinical and/or serological and/or parasitological diagnosis. For detecting antibodies in sera from dogs with leishmaniasis, the antigen showed a sensitivity of 98%, specificity of 95%, and concordance of 93% and when used for detecting antibodies in human sera presented a sensitivity of 92%, specificity of 100%, and concordance of 92%. Comparison between ELISA and IFAT demonstrated that ELISA using the LMS antigen yielded more reliable results than IFAT. The LMS antigen displayed no cross-reactivity with sera from patients or dogs that had any of the other diseases tested.Leishmaniasis comprises a spectrum of diseases widely distributed in tropical and subtropical countries, ranging in severity from self-healing skin lesions to severely mutilating mucocutaneous involvement or visceral infections (kala-azar) caused by the protozoan hemoflagellate Leishmania. The leishmanial diseases, except for cutaneous leishmaniasis, have a lengthy incubation period, an insidious onset, and a chronic course. Kala-azar, or visceral leishmaniasis (VL), is characterized by irregular fever, progressive enlargement of the spleen and liver, leukopenia with marked neutropenia, anemia, emaciation, and discoloration of the skin. Leishmanial infections are accompanied by a dramatic humoral response against some forms of leishmania. A marked increase in immunoglobulin G (IgG) in serum and, to a lesser extent, IgM is the common feature in the majority of kala-azar patient sera (17).The antigens used in immunodiagnosis consist of a repertoire of at least 30 somatic antigens and an unknown number of surface components, and the existence of both heterospecific antigens and specific parasite antigens has been established (23, 27). As a result, to date most immunodiagnostic methods have been hampered by the problem of cross-reactivities of species within a family as well as with phylogenetically distant microorganisms (4,22,23,31,35). The problem is further complicated in geographical areas where different forms of leishmaniasis and trypanosomal infections occur simultaneously (27).The serological test most commonly used for diagnosis of leishmani...

No abstract