Multibacillary leprosy by population groups in Brazil: Lessons from an observational study

<div><p>Background</p><p>Leprosy remains an important public health problem in Brazil where 28,761 new cases were diagnosed in 2015, the second highest number of new cases detected globally. The disease is caused by <i>Mycobacterium leprae</i>, a pathogen spread by patients with multibacillary (MB) leprosy. This study was designed to identify population groups most at risk for MB disease in Brazil, contributing to new ideas for early diagnosis and leprosy control.</p><p>Methods</p><p>A national databank of cases reported in Brazil (2001–2013) was used to evaluate epidemiological characteristics of MB leprosy. Additionally, the databank of a leprosy reference center was used to determine factors associated with higher bacillary loads.</p><p>Results</p><p>A total of 541,090 cases were analyzed. New case detection rates (NCDRs) increased with age, especially for men with MB leprosy, reaching 44.8 new cases/100,000 population in 65–69 year olds. Males and subjects older than 59 years had twice the odds of MB leprosy than females and younger cases (OR = 2.36, CI95% = 2.33–2.38; OR = 1.99, CI95% = 1.96–2.02, respectively). Bacillary load was higher in male and in patients aged 20–39 and 40–59 years compared to females and other age groups. From 2003 to 2013, there was a progressive reduction in annual NCDRs and an increase in the percentage of MB cases and of elderly patients in Brazil. These data suggest reduction of leprosy transmission in the country.</p><p>Conclusion</p><p>Public health policies for leprosy control in endemic areas in Brazil should include activities especially addressed to men and to the elderly in order to further reduce <i>M</i>. <i>leprae</i> transmission.</p></div

Mean new case detection rates (NCDR) of leprosy in Brazil (2001–2013).

<p>3a) NCDR by sex according to age group. 3b) NCDR by sex and operational classification according to age group. MB: multibacillary, PB: paucibacillary.</p

Correlation between Central Memory T Cell Expression and Proinflammatory Cytokine Production with Clinical Presentation of Multibacillary Leprosy Relapse

<div><p>Background</p><p>Despite the efficacy of multidrug therapy, surviving <i>Mycobacterium leprae</i> causes relapse in some leprosy patients, and these patients present signs and symptoms of disease after healing. This study focused on the cellular immune response in relapsed multibacillary patients but also included non-relapsed multibacillary cured individuals, newly diagnosed and untreated multibacillary patients, paucibacillary patients just before the beginning of treatment, and voluntary healthy individuals for comparative analysis.</p><p>Methodology/Principal Findings</p><p>Inhibition of CD86 expression in the blood-derived monocytes and dendritic cells of relapsed multibacillary patients, either <i>ex vivo</i> or after <i>M</i>. <i>leprae</i> antigen stimulation was observed by flow cytometry. In addition, no significant changes in Interferon-gamma (IFN-γ) expression were observed in 5-day culture supernatants of relapsed patients in response to <i>M</i>. <i>leprae</i>, neither before nor after treatment, as measured by ELISA. However, these patients demonstrated a significant increase in central memory CD4+ and CD8+ <i>M</i>. <i>leprae</i>-specific T cells, as assessed by multiparametric flow cytometry. The increase in frequency of central memory T cells in relapsed patients strongly correlated with the bacillary index and the number of skin lesions observed in these subjects. Moreover, cytokine multiplex analysis demonstrated significant antigen-specific production of Interlukin-1beta (IL-1b), IL-6, and Tumour Necrosis Factor (TNF) in the relapsed group with extremely low IL-10 production, which resulted in a high TNF/IL-10 ratio.</p><p>Conclusions/Significance</p><p>Inhibition of CD86 expression may function to reduce effector T cell responses against the <i>M</i>. <i>leprae</i> antigen. Furthermore, the predominance of central memory T cells in association with the high TNF/IL-10 ratio and no observed IFN-γ production may be related to the pathogenesis of relapse in multibacillary leprosy. Therefore, our findings may be a direct result of the clinical presentation, including a number of skin lesions and bacterial load, of relapsed patients. To our knowledge, this is the first study correlating immune response parameters with the clinical presentation of relapsed multibacillary patients.</p></div

Annual indicators for leprosy in Brazil (2001–2013)

<p>Annual indicators for leprosy in Brazil (2001–2013)</p

Mean new case detection rates (NCDR) of leprosy by time period, according to age group–Brazil (2001 to 2013).

<p>Mean new case detection rates (NCDR) of leprosy by time period, according to age group–Brazil (2001 to 2013).</p

Bacillary index of leprosy cases at diagnosis by sex according to age groups–Ambulatório Souza Araújo, Fiocruz/RJ, Brazil (1990–2014).

<p>5a = All cases; 5b = MB cases. * = extremes, dots = outliers, horizontal bar = median, box = 25–75 percentiles.</p

Baseline patterns of newly diagnosed and untreated patients, cured leprosy patients, and healthy volunteers.

<p>Baseline patterns of newly diagnosed and untreated patients, cured leprosy patients, and healthy volunteers.</p

Significant inhibition of CD86 expression in monocytes and DC from MB relapsed leprosy patients.

<p>PBMC cultures stimulated with <i>M</i>. <i>leprae</i> (20 μg/mL) and LPS (1 μg/mL) for 24 h were analyzed by flow cytometry (FACSAria, BD). After gating the monocytes and DC region, based on forward and side scatter and the negative region defined with isotype control antibodies for each cell population, CD86 expression was obtained both in monocytes (CD3-/CD83-/CD14+; A) and DC (CD3-/CD14-/CD83+; B). On the left, the bars of both graphics correspond to antigen stimulation, while those on the right correspond to LPS stimulation, in accordance with the assessed groups. The results are expressed as percentage variation, calculated according to the following formula: [CD86 expression in ML-stimulated cultures (%) / CD86 expression in unstimulated cultures (%) × 100] −100; C). A representative example of the flow cytometric determination of CD86 expression in unstimulated (UNS), <i>M</i>. <i>leprae</i> stimulated (ML), and LPS stimulated monocytes, and DC from a relapsed patient (upper dot plots) and a healthy volunteer (lower dot plots). The numbers inside the dot plots represent the percentage of CD86 positive cells in monocytes (CD83-; lower right panels) and DC (CD83+; upper right panels).</p

Mean new case detection rates (NCDR) of leprosy by Brazilian state (2001 to 2013).

<p>Mean new case detection rates (NCDR) of leprosy by Brazilian state (2001 to 2013).</p

Sex ratio of leprosy cases detected without disabilities, by operational classification according to age group–Brazil.

<p>MB: multibacillary, PB: paucibacillary.</p