Frequency of Leishmania spp. infection among HIV-infected patients living in an urban area in Brazil: a cross-sectional study.

BACKGROUND: There is little information about the frequency of Leishmania infection in asymptomatic people living with HIV (PLWH) and about the performance of laboratory diagnostic methods in coinfected patients in Latin America. The main objective of this study is to evaluate the frequency of Leishmania spp. infection in HIV-infected patients living in an urban area in Brazil. METHODS: To detect Leishmania infection, diagnostic tests were performed to detect anti-Leishmania antibodies (ELISA using Leptomonas seymouri antigens; ELISA using rK39 antigens; ELISA using rK28 antigens; indirect fluorescent-antibody test (IFAT); direct agglutination test (DAT)) and Leishmania DNA (polymerase chain reaction (PCR) with the target genes kDNA and ITS-1). RESULTS: The frequency of at least one positive test was 15%. For ELISA using Leptomonas antigens and IFAT, there was an association between CD4+ T lymphocyte counts and test positivity, with a higher positivity of these tests in more immunosuppressed patients (CD4+ T cell count < 200/mm3). CONCLUSIONS: According to our data, there was a high prevalence of Leishmania spp. infections in this population living with HIV. Although there is the possibility of cross-reaction, some tests that are considered highly specific for the diagnosis of Leishmania infection were positive. There was also an association between the positivity of some tests studied and lower values of CD4+ T lymphocytes.

Chagas' disease: application of TESA-blot in inconclusive sera from a Brazilian blood bank.

BACKGROUND AND OBJECTIVES: The procedure used for screening Trypanosoma cruzi-infected blood donors by using two serological techniques has frequently led to discordant results. The TESA-blot, a confirmatory test for Chagas' disease, was applied in a survey of inconclusive sera from a Brazilian blood bank. MATERIALS AND METHODS: Four hundred and forty-eight sera, obtained from blood donors at the HRU-Fundação Hemominas, were tested by using the TESA-blot assay, a Western blotting method. Of these 448 sera, 348 had previously been determined as inconclusive for Chagas' disease owing to discordance between the indirect immunofluorescence assay (IFA) and the enzyme-linked immunosorbent assay (ELISA). RESULTS: The TESA-blot was positive for 2.87% (10/348) of the inconclusive sera, and 100% positive and negative for the sera from chagasic (n=50) and non-chagasic (n=50) donors, respectively. CONCLUSIONS: Our results clearly indicate the need to improve the diagnosis of Chagas' disease in blood banks by using new confirmatory diagnostic test(s). The TESA-blot, a new test with trypomastigote fractions of the T. cruzi Y strain, has made new approaches to the confirmation of Chagas' disease possible.

Immunoblot analysis of trypomastigote excreted-secreted antigens as a tool for the characterization of Trypanosoma cruzi strains and isolates.

An analysis of antibody recognition of Trypanosoma cruzi exoantigens by immunoblotting revealed a unique banding pattern that seems to be characteristic of each strain or isolate. Trypomastigote excreted-secreted antigens (TESA) present in supernatants of LLC-MK2 cells infected with 5 strains and 10 isolates of T. cruzi produced 13 different immunoblotting patterns. The same bands were observed when probed with acute-phase Chagas' disease serum or with serum from a rabbit immunized with the repetitive domain of T. cruzi transialidase recombinant protein (anti-shed acute-phase antigens). Three similar patterns were observed with TESA from 3 human isolates that probably belong to the same T. cruzi strain. When clone CL Brener, clone CL-14, and CL parental strain were analyzed, the same bands were observed, although they presented different biological behavior. These results suggest that immunoblotting analysis of TESA may be a useful tool for characterization of T. cruzi strains and isolates.

Immunoblot assay using excreted-secreted antigens of Trypanosoma cruzi in serodiagnosis of congenital, acute, and chronic Chagas' disease.

Immunoblotting with trypomastigote excreted-secreted antigens (TESA blot) of Trypanosoma cruzi was evaluated as a method for diagnosis of chronic and acute phases as well as congenital (in newborn children) Chagas' disease. Serum samples from acute-phase and congenital infections were considered to be positive when they reacted with ladder-like bands of 130- to 200-kDa antigens, recognized by immunoglobulin M (IgM) and IgG antibodies, while IgG from chronic-phase sera recognized a broad band antigen of 150 to 160 kDa. Nonchagasic sera were not reactive to these antigens. The study was carried out on 512 patients, 111 of whom were nonchagasic but included cases of leishmaniasis or other pathologies, and 401 chagasic patients. The latter group comprised 361 chronic cases, 36 acute cases, and 4 congenital cases in newborn children. Among the chronic cases, 256 were from areas in which T. cruzi is endemic but which differed widely in the pathogenic expression of T. cruzi infection and in parasitemia levels. These patients at the same time showed a broad range of low, medium, and high reactivity to conventional enzyme-linked immunosorbent assays and indirect immunofluorescence serotests for Chagas' disease. For these reasons they may better represent the universe of chagasic patients than would a sample of highly reactive sera obtained from chagasic patients in a single area endemic for T. cruzi. All acute and congenital cases showed positivity in the IgM and IgG TESA blots, while chronic cases were 100% positive for IgG antibodies. In nonchagasic sera, including 30 cases of visceral and muco-cutaneous leishmaniasis, the specificity index was 1.000, and no cross-reactions were observed. The TESA blot thus seems to be useful as a sensitive and specific diagnostic assay in cases of suspected acute or congenital T. cruzi infection and as a general confirmatory test for conventional Chagas' disease serology.