This study aims at estimating the prevalence of Leishmania infection among HIV-infected patients through the use of non-invasive tests. The study was conducted in three Infectious Diseases Services in two large Brazilian cities, both endemic areas for visceral leishmaniasis. Three hundred and eighty-one asymptomatic patients were enrolled whose ages ranged from 19 to 58 years old; 63.5% were men; mean TCD4+ was 380 cells/μl; and mean viral load was 153800 copies/ml. All individuals were tested for Leishmania infection through: ELISA using crude Leishmania infantum (ELISA), ELISA using the recombinant K39 antigen (rK39), indirect fluorescent antibody test (IFAT) and PCR targeted to kDNA region. The tests' positivity were: 10.8% (ELISA), 3.9% (IFAT), 0.8% (rK39), 6.3% PCR and 20.2% (overall, at least one positive test), with no statistical correlation between positivity and clinical and laboratorial variables. Concordance among tests was low (Kappa <0.20). Prevalence of Leishmania asymptomatic infection was high in this population, reinforcing the need for attention in the evaluation of HIV patients from endemic areas. New efforts are needed to develop more specific and sensitive tests to diagnose Leishmania asymptomatic infection. Highly active antiretroviral therapy (HAART) seems to have a protective role against disease progression in co-infected individuals.

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A polymerase chain reaction (PCR) assay for the detection of Leishmania spp. DNA in peripheral blood was optimized and evaluated for the diagnosis of human visceral leishmaniasis (VL) in Brazil during May 2001 to December 2002. Optimization of the technique resulted in a detection limit of 1.65 fg of purified L. (L.) chagasi DNA, equivalent to 1.65 x 10(-2) parasites. Leishmania DNA was detected in the blood of 48 of 53 patients with parasitologically-confirmed VL, which corresponds to a sensitivity of 91%. No DNA was detected in the peripheral blood of 15 healthy, non-exposed volunteers, giving a specificity of 100%. We conclude that detection of parasite DNA in peripheral blood offers a non-invasive, sensitive and rapid method for the detection of VL caused by L. (L.) chagasi.

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