Five serological tests for the diagnosis of visceral leishmaniasis (VL) were compared: a direct agglutination test (DAT) based on freeze-dried antigen (DAT-fd); a locally produced DAT (DAT-LPC); an IgG ELISA against rK39 (ELISA-rK39); an IgG ELISA for Leishmania chagasi (ELISA-L. chagasi); and an IgG IFAT against L. chagasi. Serum samples from 88 patients with VL, 20 non-infected individuals and 85 patients with others infectious diseases were evaluated. The sensitivity rates were: DAT-fd, 96.6%; DAT-LPC, 95.5%; ELISA-rK39, 88.6%; ELISA-L. chagasi, 89.8%; and IFAT, 92.0% (P>0.05). The specificity for the control groups varied from 53.3% to 100%. DAT-fd had the highest efficiency (97.4%), followed by DAT-LPC (91.7%) and ELISA-rK39 (90.7%). Our data suggest that DAT-fd, DAT-LPC and ELISA-rK39 are useful tests for the diagnosis of VL and could replace IFAT as the routine diagnostic test in Brazil.

Peripheral blood samples of 138 co-habitants from 25 families with recently diagnosed cases of visceral leishmaniasis in the Metropolitan Region of Belo Horizonte, Minas Gerais, Brazil, were analyzed by indirect fluorescent antibody test (IFAT), rK39 and Leishmania chagasi Enzyme Linked Immunosorbent Assay (ELISA), intradermal skin-test and Polymerase Chain Reaction (PCR) over a 12-month period. The cumulative positivity was significantly higher by PCR (29.7%) than by IFAT, rK39 ELISA, L. chagasi ELISA and intradermal skin-test (5.1%, 6.5%, 14.5% and 2.9%, respectively). In addition, the cytokine profile was measured in 16 of the 138 volunteers, of whom eight were asymptomatic carriers and eight were non-infected co-habitants. The innate immunity cells from asymptomatic carriers displayed, upon in vitro antigenic stimulation, a modulated increase in cytokine synthesis that was distinct from that observed in non-infected volunteers. This study suggests that the identification of a large proportion of asymptomatic carriers is facilitated when more than one diagnostic method is applied and that a mixed pattern of immune response is correlated with clinical status of asymptomatic individuals. These observations suggest also that asymptomatic infection by L. chagasi is a frequent event and that control programs could benefit by including this indicator in their interventions.

Resumo A pandemia da “novel coronavirus disease” 2019 (COVID-19), infecção causada pelo coronavírus 2 da síndrome respiratória aguda grave (SARS-CoV-2), tem descortinado uma realidade até então oculta: a vulnerabilidade da população residente em instituições de longa permanência para idosos (ILPI). Diversas publicações científicas têm revelado a concentração de até 60% dos óbitos atribuídos à COVID-19 em tais instituições. A maioria dos residentes em ILPI reúnem os principais fatores de risco para morbimortalidade pela COVID-19, o que torna imprescindível a definição de ações voltadas à prevenção da transmissibilidade do SARS-CoV-2 neste ambiente, além das medidas usuais de distanciamento social e isolamento dos portadores da doença. Propõem-se, no presente artigo, estratégias de rastreamento da infecção em residentes e trabalhadores de ILPI por meio de testes laboratoriais disponíveis no Brasil. A identificação precoce de indivíduos portadores do SARS-CoV-2 com possibilidades de transmissão ativa e continuada do vírus permite a adoção de medidas que interrompam o ciclo de transmissão local da infecção.