Antileishmania Immunological Tests for Asymptomatic Subjects Living in a Visceral Leishmaniasis-Endemic Area in Brazil

• Published in: The American journal of tropical medicine and hygiene Vol. 84; no. 2; pp. 261 - 266
• Main Authors: ALMEIDA SILVA, Luciana, DARDO ROMERO, Héctor, NOGUEIRA NASCENTES, Gabriel Antonio, TEODORO COSTA, Roberto, RODRIGUES, Virmondes, PRATA, Aluízio
• Format: Journal Article
• Language: English
• Published: Deerfield, IL American Society of Tropical Medecine and Hygiene 01.02.2011; The American Society of Tropical Medicine and Hygiene
• Subjects: Antigens, Protozoan - immunology; Asymptomatic Infections - epidemiology; Biological and medical sciences; Brazil - epidemiology; Enzyme-Linked Immunosorbent Assay; False Positive Reactions; Fluorescent Antibody Technique; Human protozoal diseases; Humans; Infectious diseases; Leishmania; Leishmania donovani - immunology; Leishmaniasis, Visceral - diagnosis; Leishmaniasis, Visceral - epidemiology; Leishmaniasis, Visceral - immunology; Leshmaniasis; Medical sciences; Parasitic diseases; Protozoal diseases; Sensitivity and Specificity; Seroepidemiologic Studies; South America; Brazil; America; Montenegro; Infection; Human; Protozoal disease; Kala azar; Tropical medicine; Asymptomatic; Leishmaniasis; Parasitosis
• ISSN: 0002-9637; 1476-1645
• DOI: 10.4269/ajtmh.2011.10-0092

The objective of this study was to evaluate the behavior of different tests used for the diagnosis of visceral leishmaniasis (VL) in asymptomatic subjects living in an endemic area. No gold standard is available for the diagnosis of asymptomatic infection with Leishmania. In continuation of a previous study, 1,017 subjects living in a VL-endemic area were clinically reevaluated. Of these, 576 had at least one positive serological test in a first assessment. About 3 years after the first evaluation, none of the subjects had progressed to clinical VL. Among this group, 246 subjects were selected, and five serological tests (enzyme-linked immunosorbent assay p [ELISAp], ELISArK39, ELISArK26, indirect immunofluorescence test [IIFT] using L. amazonensis promastigote antigen, and an immunochromatographic test using rK39 antigen [TRALd]) and the Montenegro skin test (MST) were repeated. There was a significant increase in the number of subjects who tested positive in the MST, IIFT, ELISAp, and ELISArK39 in the second evaluation. For all tests, there were subjects who tested positive in the first evaluation and negative in the second evaluation. A positive result in the serological tests and MST in subjects from the endemic area studied did not indicate a risk of progression to VL and may only be temporary.