Soroprevalência de infecção subclínica e avaliação da estratégia imunoquimioprofilática às respostas sorológicas em contatos de casos novos de hanseníase diagnosticados em menores de 15 anos

Abstract

Introduction: Leprosy, a disabling chronic infectious disease characterized by a spectrum of dermatoneurological manifestations associated with different patterns of immune response. It remains a public health challenge in several regions, particularly among vulnerable populations in endemic areas. To evaluate the prevalence of Mycobacterium leprae through the PGL-1 and LID-1 tests and the immunochemoprophylactic strategy to the responses of IFN-gamma and heme oxygenase-1 (HO-1) as a measure to protect against the disease in contacts of new cases of leprosy diagnosed in children under 15 years of age. The thesis is structured into three manuscripts, each corresponding to specific objectives. The first comprises an updated systematic review, followed by a cross-sectional study to analyze seroprevalence and an intervention study that analyzes the immunochemoprophylactic strategy with single-dose rifampicin combined with the BCG-ID vaccine. For the systematic review, the Joanna Briggs Institute (JBI) methodology was adopted to evaluate the effectiveness of chemoprophylaxis in leprosy contacts. The cross-sectional and intervention studies involved serological screening for Mycobacterium leprae using the PGL-1 and LID-1 tests, in addition to the assessment of the IFN-gamma and HO-1 markers before and after the administration of chemoprophylaxis and the BCG-ID vaccine, in Cuiabá, Mato Grosso, Brazil. The samples in these studies included household and neighborhood contacts of new cases of multibacillary leprosy in children under 15 years of age. Data management and analysis were carried out using SPSS 22 (Statistical Package for the Social Sciences) and R (RStudio, version 4.3.2) software. The main results indicate that rifampicin, when combined with BCG vaccination and other prophylactic measures, highlights its role in reducing the incidence of leprosy in different populations and contexts; the correlation between PGL-1 and LID-1 tests suggested significant exposure to Mycobacterium leprae among household contacts; and, a significant reduction in the serological conversion rate among contacts who received the intervention, suggesting the effectiveness of the combined strategy in preventing leprosy. Furthermore, the analysis of immune responses indicated a positive modulation in the markers IFN-gamma and HO-1, reinforcing the hypothesis that chemoprophylaxis combined with immunoprophylaxis can provide additional protection against the disease. This study expands knowledge about preventive strategies against leprosy, highlighting the potential of combined approaches to control transmission in high-risk populations. The results reiterate the importance of integrating chemoprophylaxis and immunoprophylaxis into public health policies, pointing to the need for comprehensive strategies that facilitate the implementation and acceptance of these interventions. The findings reinforce the need for public policies that integrate chemoprophylaxis and immunoprophylaxis as central components of leprosy prevention initiatives.