Seroprevalence of ML Flow test in leprosy contacts from State of Minas Gerais, Brazil

ML Flow serological test: complementary tool in leprosy

BACKGROUND

The evaluation of household contacts of leprosy cases allows the early diagnosis of new cases.

OBJECTIVE

To associate the results of the ML Flow test with the clinical characteristics of leprosy cases and to verify their positivity in household contacts, in addition to describing the epidemiological profile of both.

METHODS

Prospective study with patients diagnosed over the course of one year (n = 26), without prior treatment, and their household contacts (n = 44) in six municipalities in northwestern São Paulo, Brazil.

RESULTS

There was a predominance of men among the leprosy cases, of 61.5% (16/26); 77% (20/26) were over 35 years old; 86.4% (22/26) were multibacillary; 61.5% (16/26) had a positive bacilloscopy; and 65.4% (17/26) had no physical disability. The ML Flow test was positive in 53.8% (14/26) of the leprosy cases and was associated with those who had a positive bacilloscopy and were diagnosed as multibacillary (p-value <0.05). Among the household contacts, 52.3% (23/44) were women and aged over 35 years; 81.8% (36/44) had been vaccinated with BCG ‒ Bacillus Calmette-Guérin. The ML Flow test was positive in 27.3% (12/44) of household contacts, all of whom lived with multibacillary cases; seven lived with positive bacilloscopy cases and six with consanguineous cases.

STUDY LIMITATIONS

Difficulty in convincing the contacts to undergo the evaluation and collection of the clinical sample.

CONCLUSION

The ML Flow test, when positive in household contacts, can help the identification of cases that require more attention by the health team, as it indicates a predisposition to disease development, especially when they are household contacts of multibacillary cases, with positive bacilloscopy and consanguineous. The ML Flow test also helps in the correct clinical classification of the leprosy cases.

Laboratory diagnosis of leprosy: Two staining methods from bacilloscopy and rapid ml flow test

Background

The diagnosis of leprosy is based on the characteristic signs and symptoms of the disease, subsidized by laboratory tests. When positive, the bacilloscopy closes the diagnosis for leprosy. Phenolic glycolipid-I, or PGL-I, is a molecule in the bacillus cell wall that confers a greater immune response. The ML Flow test is an immunochromatographic test for the detection of anti-PGL-I IgM in human blood or serum.

Methods

A prospective study with data collection and biological materials in patients with suspected leprosy from August 2020 to May 2021. For microscopy, intradermal smears were stained with Auramine O, and after reading under a fluorescence microscope, reviewed by Ziehl-Neelsen. The ML flow test was performed according to the Bührer-Sékula protocol. To assess the agreement between the methods, the Kappa index was estimated.

Results

Of the 94 suspected leprosy patients, 31 (32.9%) were diagnosed with leprosy. There was moderate agreement between the results of the ML Flow and Auramine O tests (Kappa = 0.58) and substantial agreement between the ML Flow and Ziehl-Neelsen microscopy (Kappa = 0.72). In paucibacillary cases, serology was positive in 100% of patients.

Conclusions

This study concluded that the Ziehl-Neelsen technique remains the best option for standard leprosy staining, and the ML flow test is more positive among the three techniques evaluated and can be an effective tool in the early diagnosis of leprosy cases.

Detection of anti-M. leprae antibodies in children in leprosy-endemic areas: A systematic review

BACKGROUND

Leprosy elimination primarily targets transmission of Mycobacterium leprae which is not restricted to patients' households. As interruption of transmission is imminent in many countries, a test to detect infected asymptomatic individuals who can perpetuate transmission is required. Antibodies directed against M. leprae antigens are indicative of M. leprae infection but cannot discriminate between active and past infection. Seroprevalence in young children, however, reflects recent M. leprae infection and may thus be used to monitor transmission in an area. Therefore, this literature review aimed to evaluate what has been reported on serological tests measuring anti-M. leprae antibodies in children without leprosy below the age of 15 in leprosy-endemic areas.

METHODS AND FINDINGS

A literature search was performed in the databases Pubmed, Infolep, Web of Science and The Virtual Health Library. From the 724 articles identified through the search criteria, 28 full-text articles fulfilled all inclusion criteria. Two additional papers were identified through snowballing, resulting in a total of 30 articles reporting data from ten countries. All serological tests measured antibodies against phenolic glycolipid-I or synthetic derivatives thereof, either quantitatively (ELISA or UCP-LFA) or qualitatively (ML-flow or NDO-LID rapid test). The median seroprevalence in children in endemic areas was 14.9% and was stable over time if disease incidence remained unchanged. Importantly, seroprevalence decreased with age, indicating that children are a suitable group for sensitive assessment of recent M. leprae infection. However, direct comparison between areas, solely based on the data reported in these studies, was impeded by the use of different tests and variable cut-off levels.

CONCLUSIONS

Quantitative anti-PGL-I serology in young children holds promise as a screening test to assess M. leprae infection and may be applied as a proxy for transmission and thereby as a means to monitor the effect of (prophylactic) interventions on the route to leprosy elimination.

AN. Vulnerabilidade programática no controle da hanseníase: padrões na perspectiva de gênero no Estado da Bahia, Brasil

O objetivo deste estudo foi analisar indicadores operacionais de controle da hanseníase e sua tendência temporal, na perspectiva de gênero, no Estado da Bahia, Brasil, de 2001 a 2014. Trata-se de estudo de série temporal baseado em dados epidemiológicos da hanseníase no Sistema de Informação de Agravos de Notificação, com análise de regressão de Poisson por joinpoints e de regressão polinomial. Dos 40.054 casos novos de hanseníase analisados, 47,1% dos contatos registrados não foram examinados, mas com tendência significativa de aumento, de forma mais acentuada entre as mulheres (variação percentual anual média - AAPC = 5,6; IC95%: 3,5; 7,7) em comparação aos homens (AAPC = 3,0; IC95%: 0,5; 5,6). A proporção de cura na coorte 2003-2014 foi de 85%, com tendência de redução mais acentuada nos homens (AAPC = -0,5; IC95%: -0,9; 0,0), comparados às mulheres (AAPC = -0,4; IC95% -0,7; -0,1). A proporção de casos em abandono de tratamento no período foi de 5,5%, com tendência de redução mais significativa entre mulheres (AAPC = -4,9; IC95%: -8,7; -1,1) do que em homens (AAPC = -2,7; IC95%: -4,4; -1,0). Recidiva foi verificada em 3,8% de todas as entradas do período; as mulheres apresentaram tendência de redução significativa (AAPC = -2,2; IC95%: -3,3; -1,0) e os homens, de crescimento significativo (AAPC = 4,9; IC95%: 2,9; 6,8). A análise por regressão polinomial foi consistente com a análise de joinpoints. A hanseníase no Estado da Bahia apresenta indicadores operacionais com magnitude e tendência temporal significativas, em especial entre a população masculina. O desempenho insuficiente dos serviços de saúde em realizar a vigilância de contatos e a longitudinalidade do cuidado revelam diferentes dimensões de vulnerabilidade.

Factors associated with anti-phenolic glycolipid-I seropositivity among the household contacts of leprosy cases

BACKGROUND

The diagnosis of leprosy is based on clinical symptoms of the disease, which may not be sufficient to ensure early diagnosis. The development of effective tools for the early detection of infection, such as rapid tests that can be applied by non-specialists for early-stage leprosy identification, has been considered a research priority and may contribute to overcoming the complications associated with late diagnosis. The aim of this study was to analyze the factors associated with anti-phenolic glycolipid-I (PGL-I) seropositivity among the household contacts of leprosy cases.

METHODS

A cross-sectional study of individuals from the northeastern municipalities of the state of Minas Gerais, Brazil, was performed. Anti-PGL-I seropositivity was evaluated by assessing specific antibody production using the ML Flow test. A Poisson regression with a robust error variance was used to evaluate the relationship between anti-PGL-I seropositivity and the independent variables investigated.

RESULTS

The overall anti-PGL-I seropositivity was 13.5 %, and among the contacts of leprosy cases that were classified as paucibacillary or multibacillary, it was 8.4 and 17.3 %, respectively. The factors associated with the variation of anti-PGL-I seropositivity among the study population were the presence of signs suggestive of leprosy (PR = 3.68; 95 % CI: 1.56-8.71), the operational leprosy classification (PR = 2.17; 95 % CI: 1.22-3.86) and grade 1 (PR = 1.83; 95 % CI: 1.02-3.26) or grade 2 disability (PR = 2.42; 95 % CI: 1.02-5.47) of the index leprosy case.

CONCLUSIONS

The presence of signs suggestive of leprosy and the operational classification of leprosy cases were associated with anti-PGL-I seropositivity. The serological tests available for leprosy are not considered to be diagnostic tests but can be used as auxiliary assessments in combination with clinical parameters to identify exposed individuals at high risk of developing leprosy and those exhibiting the initial stages of this disease.

Serology with ML Flow test in health professionals from three different states of Brazil

BACKGROUND

In highly endemic countries, transmission and sub-clinical infection of leprosy are likely and the disease manifests itself in individuals without any known close contact with a leprosy patient. Health workers are social contacts belonging to the same network (the Health System) and some of them share the same social environment (nursing assistants) as patients with known patients and / or carriers.

OBJECTIVE

To identify ML Flow seropositivity among health professionals.

METHODS

We conducted a cross-sectional study using a serological survey with the ML Flow test in 450 health professionals (doctors, nurses and nursing assistants), in order to detect seropositivity in areas of high and low endemicity in municipalities from three Brazilian states (RJ, MS and RS).

RESULTS

The results showed general 16% seropositivity, higher in low endemic areas, regardless of whether there was direct care for leprosy patients. Paradoxically, a statistical association was observed between the area studied and seropositivity, as the place with the lowest endemicity (CA) had the highest seropositivity rate (p = 0.033).

CONCLUSION

The authors suggest these results are associated with a presence of an unspecified link to bovine serum albumin (BSA), carrier of PGL-1 in the ML Flow test, and recommend expanded seroepidemiological research utilizing tests with human and bovine albumin.

Sex bias in infectious disease epidemiology: patterns and processes

BACKGROUND

Infectious disease incidence is often male-biased. Two main hypotheses have been proposed to explain this observation. The physiological hypothesis (PH) emphasizes differences in sex hormones and genetic architecture, while the behavioral hypothesis (BH) stresses gender-related differences in exposure. Surprisingly, the population-level predictions of these hypotheses are yet to be thoroughly tested in humans.

METHODS AND FINDINGS

For ten major pathogens, we tested PH and BH predictions about incidence and exposure-prevalence patterns. Compulsory-notification records (Brazil, 2006-2009) were used to estimate age-stratified ♂:♀ incidence rate ratios for the general population and across selected sociological contrasts. Exposure-prevalence odds ratios were derived from 82 published surveys. We estimated summary effect-size measures using random-effects models; our analyses encompass ∼0.5 million cases of disease or exposure. We found that, after puberty, disease incidence is male-biased in cutaneous and visceral leishmaniasis, schistosomiasis, pulmonary tuberculosis, leptospirosis, meningococcal meningitis, and hepatitis A. Severe dengue is female-biased, and no clear pattern is evident for typhoid fever. In leprosy, milder tuberculoid forms are female-biased, whereas more severe lepromatous forms are male-biased. For most diseases, male bias emerges also during infancy, when behavior is unbiased but sex steroid levels transiently rise. Behavioral factors likely modulate male-female differences in some diseases (the leishmaniases, tuberculosis, leptospirosis, or schistosomiasis) and age classes; however, average exposure-prevalence is significantly sex-biased only for Schistosoma and Leptospira.

CONCLUSIONS

Our results closely match some key PH predictions and contradict some crucial BH predictions, suggesting that gender-specific behavior plays an overall secondary role in generating sex bias. Physiological differences, including the crosstalk between sex hormones and immune effectors, thus emerge as the main candidate drivers of gender differences in infectious disease susceptibility.