Sergio Araujo

Unveiling healthy carriers and subclinical infections among household contacts of leprosy patients who play potential roles in the disease chain of transmission

Leprosy transmission still occurs despite the availability of highly effective treatment. The next step towards successfully eliminating leprosy is interrupting the chain of transmission of the aetiological agent, Mycobacterium leprae. In this investigation, we provide evidence that household contacts (HHCs) of leprosy patients might not only have subclinical infections, but may also be actively involved in bacilli transmission. We studied 444 patients and 1,352 contacts using anti-phenolic glycolipid-I (PGL-I) serology and quantitative polymerase chain reaction (qPCR) to test for M. leprae DNA in nasal swabs. We classified the patients according to the clinical form of their disease and the contacts according to the characteristics of their index case. Overall, 63.3% and 34.2% of patients tested positive by ELISA and PCR, respectively. For HHCs, 13.3% had a positive ELISA test result and 4.7% had a positive PCR test result. The presence of circulating anti-PGL-I among healthy contacts (with or without a positive PCR test result from nasal swabs) was considered to indicate a subclinical infection. DNA detected in nasal swabs also indicates the presence of bacilli at the site of transmission and bacterial entrance. We suggest that the concomitant use of both assays may allow us to detect subclinical infection in HHCs and to identify possible bacilli carriers who may transmit and disseminate disease in endemic regions. Chemoprophylaxis of these contacts is suggested.

Identification of clinical, epidemiological and laboratory risk factors for leprosy reactions during and after multidrug therapy

This cross-sectional retrospective study evaluated 440 leprosy patients; 57% (251/440) had leprosy reactions during and/or after multidrug therapy, 80.5% (202/251) of whom presented with multibacillary leprosy. At diagnosis, positive bacterial index (BI) [odds ratio (OR) = 6.39; 95% confidence interval (CI): 4.1-10.1)] or polymerase chain reaction (PCR) (OR = 9.15; 95% CI: 5.4-15.5) in skin smears, anti-phenolic glycolipid-1 (anti-PGL-1) ELISA (OR = 4.77; 95% CI: 2.9-7.9), leucocytosis (OR = 9.97; 95% CI: 3.9-25.7), thrombocytopenia (OR = 5.72; 95% CI: 2.3-14.0) and elevated lactate dehydrogenase (OR = 2.38; 95% CI: 1.4-4.0) were potential markers for the development of reactions during treatment. After treatment, positive BI (OR = 8.47; 95% CI: 4.7-15.3) and PCR (OR = 6.46; 95% CI: 3.4-12.3) in skin smears, anti-PGL-1 ELISA (OR = 2.25; 95% CI: 1.3-3.9), anaemia (OR = 2.36; 95% CI: 1.2-4.5), leucocytosis (OR = 4.14; 95% CI: 1.5-11.6) and thrombocytopenia (OR = 3.70; 95% CI: 1.3-2.2) were risk factors for the occurrence of reactions during the study period. The identification of groups with an increased risk for developing reactions will allow for the timely development of a treatment plan to prevent nerve damage and, therefore, the appearance of the disabling sequelae associated with the stigma of leprosy.

Mycobacterium leprae DNA in peripheral blood may indicate a bacilli migration route and high-risk for leprosy onset

Leprosy epidemiological studies have been restricted to Mycobacterium leprae DNA detection in nasal and oral mucosa samples with scarce literature on peripheral blood. We present the largest study applying quantitative real-time PCR (qPCR) for the detection of M. leprae DNA in peripheral blood samples of 200 untreated leprosy patients and 826 household contacts, with results associated with clinical and laboratory parameters. To detect M. leprae DNA a TaqMan qPCR assay targeting the M. leprae ML0024 genomic region was performed. The ML0024 qPCR in blood samples detected the presence of bacillus DNA in 22.0% (44/200) of the leprosy patients: 23.2% (16/69) in paucibacillary (PB), and 21.4% (28/131) in multibacillary (MB) patients. Overall positivity among contacts was 1.2% (10/826), with similar percentages regardless of whether the index case was PB or MB. After a follow-up period of 7 years, 26 contacts have developed leprosy. Comparing the results of healthy contacts with those that become ill, ML0024 qPCR positivity at the time of diagnosis of their index case represented an impressive 14.78-fold greater risk for leprosy onset (95% CI 3.6-60.8; p <0.0001). In brief, contacts with positive PCR in blood at diagnosis of index cases are at higher risk of later leprosy onset and this marker might be combined with other prognostic markers for management of contacts, which requires further studies.

Antigen-specific assessment of the immunological status of various groups in a leprosy endemic region

BackgroundSerological tests can be important tools to assist in the diagnosis of leprosy and can contribute to an earlier diagnosis. The aim of this study was to evaluate the antibody responses against phenolic glycolipid-1 (PGL-1), natural disaccharide linked to human serum albumin via an octyl (NDO-HSA), Leprosy IDRI Diagnostic-1 (LID-1) and natural disaccharide octyl - Leprosy IDRI Diagnostic-1 (NDO-LID) in leprosy patients, household contacts of patients and the general population.MethodsEnzyme-linked immunosorbent assays were used to analyze the antigen-specific antibody responsesof 94 leprosy cases, 104 household contacts of cases and 2.494 individuals from the general population.ResultsA positive correlation was observed for the antibody responses to all antigens studied. A higher proportion of seropositivity for all antigens, along with stronger magnitude of response, was observed in multibacillary (MB) leprosy patients and household contacts of MB leprosy patients compared with the levels observed in paucibacillary (PB) leprosy patients and household contacts of PB leprosy patients. A substantial and significant positive correlation was found between seropositivity and the bacterial index for the leprosy patients. Anti-PGL-1 tests were more frequently positive than anti-NDO-HSA tests among patients with all clinical forms of leprosy and among the group of household contacts. The LID-1 and NDO-LID antigens showed a greater capacity to identify household contacts and individuals from the general population infected with M. leprae.ConclusionsTests that measure the antibody responses against LID-1, NDO-LID, NDO-HSA and PGL-1 were effective tools for the detection of patients with MB leprosy. Our data indicate that the anti-LID-1 and anti-NDO-LID responses were more effective than an anti-NDO-HSA response for the identification of individuals with subclinical infection.

Risk-benefit assessment of Bacillus Calmette-Guérin vaccination, anti-phenolic glycolipid I serology, and Mitsuda test response: 10-year follow-up of household contacts of leprosy patients

INTRODUCTION Despite multidrug therapy, leprosy remains a public health issue. The intradermal Bacillus Calmette-Guérin (BCG) vaccine, Mitsuda test (lepromin skin test), and anti-phenolic glycolipid I (PGL-I) serology are widely used in leprosy studies and have shown great epidemiological value. METHODS This longitudinal study evaluated the relative risks and benefits of these three tools by comparing results observed in household contacts (HHCs) of leprosy patients who developed leprosy with those of HHCs who did not in a population of 2,992 individuals monitored during a 10-year period. RESULTS Seventy-five (2.5%) new leprosy cases were diagnosed, including 28 (0.9%) co-prevalent cases. Therefore, for the risk-benefit assessment, 47 (1.6%) HHCs were considered as truly diagnosed during follow-up. The comparison between healthy and affected contacts demonstrated that not only did BCG vaccination increase protection, but boosters also increased to 95% relative risk (RR) reduction when results for having two or more scars were compared with having no scars [RR, 0.0459; 95% confidence interval (CI), 0.006-0.338]. Similarly, Mitsuda reactions >7mm in induration presented 7-fold greater protection against disease development compared to reactions of 0-3mm (RR, 0.1446; 95% CI, 0.0566-0.3696). In contrast, anti-PGL-I ELISA seropositivity indicated a 5-fold RR increase for disease outcome (RR, 5.688; 95% CI, 3.2412-9.9824). The combined effect of no BCG scars, Mitsuda reaction of <7mm, and seropositivity to anti-PGL-I increased the risk for leprosy onset 8-fold (RR, 8.109; 95% CI, 5.1167-12.8511). CONCLUSIONS The adoption of these combined assays may impose measures for leprosy control strategies.

Asymptomatic leprosy infection among blood donors may predict disease development and suggests a potential mode of transmission.

ABSTRACT Blood donor samples (1,007) were assessed for anti-phenolic glycolipid 1 (PGL-1) IgM antibodies and Mycobacterium leprae DNA presence, which had 3.8% and 0.3% positivity, respectively. After a 5-year follow-up period, six individuals with positive markers developed leprosy, raising the hypothesis that asymptomatic infection among blood donors may be an undisclosed mode of leprosy transmission via transfusion.

Spatial and temporal epidemiology of Mycobacterium leprae infection among leprosy patients and household contacts of an endemic region in Southeast Brazil

BACKGROUND Leprosy is a chronic infectious disease that remains a public health problem in low- and middle-income countries. Household contacts of leprosy patients (HHCs) have increased risk of developing disease and are important links in the chain of transmission of Mycobacterium leprae. Based on epidemiological and operational factors, the global elimination strategy depends on the geographic stratification of endemic areas to intensify control activities. The purpose of the study was to integrate epidemiological indicators and serology into the spatial and temporal analysis of M. leprae infection, in order to understanding of the dynamics of transmission, essential information for the control of leprosy. METHODOLOGY Using location-based technologies and epidemiological data obtained from leprosy cases (N=371) and HHCs (N=53), during a 11year period (2004-2014), we explored the spatial and temporal distribution of diagnosed cases: stratified according their disease manifestation; and of subclinical infection among HHCs: determined by serology (anti-PGL-I ELISA and anti-NDO-LID rapid lateral-flow test); in order to assess the distribution pattern of the disease and the areas of greatest risk of illness, in a highly endemic municipality (Ituiutaba, MG) in the southeast region of Brazil. RESULTS Seropositivity among HHCs was: 17% (9/53) for anti-PGL-I ELISA; and 42% for the NDO-LID rapid lateral-flow test. Forty-nine percent of the contacts were seropositive to at least one of the immunological tests. DISCUSSION We observed substantial spatial heterogeneity of cases throughout the urban perimeter. Even so, four main clusters of patients and three main clusters of subclinical infection were identified. CONCLUSIONS Spatio-temporal epidemiology associated to serological assessment can identify high-risk areas imbedded within the overall epidemic municipality, to prioritize active search of new cases as well support prevention strategies in these locations of greater disease burden and transmission. Such techniques should become increasingly useful and important in future action planning of health interventions, as decisions must be made to effectively allocate limited resources.

Number of leprosy reactions during treatment: clinical correlations and laboratory diagnosis

INTRODUCTION: The occurrence of leprosy reactions, a common event during treatment, may be mostly related to the action of multidrug therapy on Mycobacterium leprae. The clinical and laboratory monitoring of patients with reactions is important, since collecting data that assists in predicting the risk of reactions may help to prevent disability. METHODS: This was a sectional study, in order to correlate clinical and laboratory diagnosis with the number of reactions during treatment. Spearmans correlation was used to verify the degree of association between the assessed variables. RESULTS: This study was conducted with 211 patients with leprosy reactions during treatment of M. leprae. The borderline tuberculoid group was the most prevalent clinical form (74/211; 35.1%) and the type one reaction showed the highest frequency (136/211; 64.5%). It was observed that 73.5% (155/211) of reactions occurred within 3 months of the initiation of multidrug therapy. The diagnostic values, including the bacterial indices (BIs) of dermal smears (r = 0.21, p < 0.05) and skin biopsies (r = 0.20; p < 0.05), showed a positive correlation with the number of reactions during treatment. CONCLUSIONS: This research showed a positive correlation between bacillary load markers and the number of leprosy reactions. This study provided scientific support to future research aiming to elucidate the influence of antigenic load on the number of leprosy reactions during treatment.