Cross-reaction of sera from patients with various infectious diseases with Leishmania infantum.

OBJECTIVE To compare and evaluate the application of indirect fluorescent antibody (IFA) and counterimmunoelectrophoresis (CIEP) for laboratory identification of visceral leishmaniasis. MATERIALS AND METHODS Serum samples from patients with malaria (Plasmodium vivax, n = 86; Plasmodium falciparum, n = 38), brucellosis (n = 26), tuberculosis (n = 31) and typhoid fever (n = 35) were examined for the presence of antibody to Leishmaniainfantum antigen using IFA and CIEP tests. RESULTS Using IFA, false-positive results were malaria (P. vivax 19.8%, P. falciparum 13.2%), tuberculosis (6.4%), brucellosis (3.8%), and typhoid fever (2.8%). Using CIEP, a lower percentage of false-positives was observed only among malaria patients (P. vivax 2.3%, P. falciparum 2.6%). Serum samples from patients with other infectious diseases were negative in the CIEP test. CONCLUSION Based on the results of this study, the CIEP technique is recommended for immunodiagnosis of visceral leishmaniasis, especially in regions where malaria, brucellosis and tuberculosis are prevalent.