Marcadores sorológicos como parâmetros de risco para o desenvolvimento da hanseníase

Abstract

Among the challenges in leprosy, they deserve attention; late diagnosis, involvement in children and limitations of biomarkers. The objective of this study was to investigate the role of serum and salivary markers in leprosy. And, specific: 1) to determine the performance of serological markers in patients with leprosy; 2) to verify the occurrence of active transmission by Mycobacterium leprae between intra- and peridomiciliary contacts of patients with leprosy; 3) to study the role of serological markers in the development of the disease. Thus, the study was divided into 3 studies. In the first, serum anti-PGL1 IgA, IgG and IgM were measured in patients with the multibacillary (MB, n = 32) and paucibacillary (PB, n = 22) forms of the disease, and in non-endemic controls (n = 17) by indirect ELISA. There was a strong correlation between IgM and IgA (r = 0.745, p <0.0001) in MB patients, whereas a moderate correlation was observed between IgM and IgG (r = 0.470, p = 0.0055). As IgA demonstrated the best performance, its use was recommended for seroepidemiological analyzes of contacts. In the second study, 169 children aged 4 to 16 years, contacts of patients with MB and PB forms in two hyperendemic cities of Alagoas were evaluated. As the IgM isotype in saliva represents recent infection, the high frequency of IgM positivity (36% in one of the municipalities) strongly suggests that active transmission of M. leprae is occurring in these communities. In the third, a prospective study was conducted, with 68 children aged 4 to 15 years, contacts of patients with leprosy. Once a year, they underwent dermatoneurological evaluation and analysis of anti-PGL1 serum markers. During the study, 23 presented lesions (33.3%) and 45 presented no suspicious lesions (66.7%), and a high IgM positivity was observed in both groups. No association has been demonstrated between IgM antibody titers and presence of lesions, nor with respect to IgA. However, there was a 3.25-fold relative risk of IgG seropositivity and presence of lesions. Eight cases were diagnosed, 5 of which were seropositive for anti-PGL1 and one case presented seropositivity for the three isotypes. The relative risk of being seropositive for IgG and presenting leprosy was 8.5 (IC95 = 4.0 - 18.0). There was no significant association between IgM and disease, nor between IgA and disease. The use of serum and salivary markers makes a great contribution to the study of leprosy, and its dosage is useful for evaluating transmission in the community and as an aid in the early diagnosis of the disease.