Seguimento soroepidemiológico de crianças e jovens contatos de pacientes com hanseníase no município de Santana do Ipanema, AL.

Abstract

Brazil is the second country with the highest number of new cases of leprosy, with 26,875 new cases diagnosed in 2017, with a detection rate of 12.73 per 100,000 inhabitants. As a result, in order to know the seroepidemiological profile of contacts, a prospective study was carried out, from January 2015 to December 2017, in Santana do Ipanema, Alagoas, with 69 contacts in the age group 4 to 15 years of leprosy cases. Blood samples were taken in order to evaluate IgM, IgG and IgA serum antibodies against glycophenolic lipid antigen-1, a specific antigen Mycobacterium leprae, etiological agent of leprosy, through indirect immune enzyme linked-immunosorbent assay. Among the contacts, 25 were classified as paucibacillary contacts (PB) and 42 as multibacillary (MB) contacts. Thirty-two participants were household contacts contacts (ID) and 37 as peridomiciliary contacts (PD). Analyses were performed using GraphPad Prism software version 6.01 and the level of statistical significance considered was ≤ 0,05. A higher frequency of positive anti-PGL-1 IgM was observed in PB and MB contacts. Regarding antibody levels, during follow-up evaluation, it was observed a decrease in IgM among the MB contacts and a decrease in IgG and IgA titers in both types of contacts. It was verified significant correlations between IgM and IgA in 2016 in the PB contacts and between IgM and IgG in 2015 and also between IgG and IgA in 2017 in the MB contacts. ID contacts presented higher anti-PGL-1 titers than PD contacts. Twenty-three participants (33.3%) presented lesions and 45 (66.7%) did not, being observed a high IgM positivity in both groups. Nonetheless, regarding the IgG isotype, a relative risk of 3.25 for the person presenting IgG seropositivity and lesions. In 2017, the contacts that presented suspicious lesions were consulted by a dermatologist. Eight cases got diagnosis of leprosy, being five seropositive to anti-PGL-1 and one seropositive for all three isotypes over the years. The anti-PGL-1 IgG was considered to be the best marker, since relative risk regarding its seropositivity and and leprosy diagnosis was 8.5 (IC95 = 4.0 - 18.0). The other validation parameters for the IgG test were: diagnostic sensitivity: 25.0% (3.2 - 65.0%); diagnostic specificity: 100.0% (92.1 -100.0%); positive predictive value: 100.0% (15.8 - 100.0%); negative predictive value: 88.2% (76.1 - 95.6%). There was found no significant association between IgM isotype and disease, nor between IgA and disease