IgM immunoglobulins reacting with the phenolic glycolipid-1 antigen from Mycobacterium leprae in sera of leprosy patients and their contacts

Prospects for new leprosy diagnostic tools, a narrative review considering ELISA and PCR assays

Slit skin smear and histopathological examinations are currently the main laboratory tools used to aid the diagnosis of leprosy. However, their sensitivity is low, and many cases are not detected. New methodologies have been studied to develop more accurate tests. This narrative review aims to raise attention to the results of molecular (polymerase chain reaction) and serological (Enzyme-Linked Immunosorbent Assay) tests applied to the diagnosis of leprosy, and to summarize the available information about the former. Original scientific articles published in indexed international journals, whose study involved aspects of the diagnosis and classification of leprosy cases or home contacts, were selected. The data were extracted independently using a standardized method that dictated the inclusion of the following information: diagnosis in Paucibacillary and Multibacillary cases and in household contacts; sample number; sample type; study design; studied variables; statistical analysis employed; main results; and limitations identified. In clinical practice, the results from molecular and serological tests are assessed separately, with moderate sensitivity and specificity. However, an integrated study of these methodologies has been suggested for greater accuracy in diagnosis.

Accuracy of Enzyme-Linked Immunosorbent Assays (ELISAs) in Detecting Antibodies against Mycobacterium leprae in Leprosy Patients: A Systematic Review and Meta-Analysis

IgM against Mycobacterium leprae may be detected by enzyme-linked immunosorbent assays (ELISAs) based on phenolic glycolipid I (PGL-I) or natural disaccharide octyl bovine serum albumin (ND-O-BSA) as antigens, and the IgG response can be detected by an ELISA based on lipid droplet protein 1 (LID-1). The titers of antibodies against these antigens vary with operational classification. The aim of this study was to compare the accuracy of ELISAs involving PGL-I and ND-O-BSA with that involving LID-1. We included studies that analyze multibacillary and paucibacillary leprosy cases and evaluate the diagnostic accuracy of ELISAs based on LID-1 and/or PGL-I or ND-O-BSA as antigens to measure antibody titers against M. leprae. Studies were found via PubMed, the Virtual Health Library Regional Portal, Literatura Latino-Americana e do Caribe em Ciências da Saúde, Índice Bibliográfico Espanhol de Ciências de Saúde, the Brazilian Society of Dermatology, National Institute for Health and Clinical Excellence, Cochrane Library, Embase (the Elsevier database), and Cumulative Index to Nursing and Allied Health Literature. The Quality Assessment of Diagnostic Accuracy Studies served as a methodological validity tool. Quantitative data were extracted using the Standards for Reporting of Diagnostic Accuracy. Sensitivity, specificity, and a diagnostic odds ratio were calculated, and a hierarchical summary receiver-operating characteristic curve and forest plots were constructed. The protocol register code for this meta-analysis is PROSPERO 2017: CRD42017055983. Nineteen studies were included. ND-O-BSA showed better overall performance in terms of sensitivity, specificity, positive and negative likelihood ratios, and diagnostic odds ratio when compared with PGL-I and LID-1. The multibacillary group showed better performance on these parameters (than the paucibacillary group did), at 94%, 99%, 129, 0.05, and 2293, respectively. LID-1 did not provide any advantage regarding the overall estimate of sensitivity in comparison with PGL-I or ND-O-BSA.

Active search for leprosy cases in Midwestern Brazil: a serological evaluation of asymptomatic household contacts before and after prophylaxis with bacillus Calmette-Guérin

Leprosy is a disease caused by Mycobacterium leprae that carries a high risk of disability, making early diagnosis mandatory. This study aimed to determine the applicability of anti-PGL-1 IgM antibody detection, using the ML FLOW technique, as an assistant tool for the detection of leprosy infection in asymptomatic household contacts (AHHC) of multibacillary leprosy index cases from Midwest Brazil. Serological changes induced by the prophylaxis of these household contacts with Bacillus Calmette-Guérin (BCG) were also verified. A total of 91 AHHC were assessed, among which, 18.68% (n = 17) presented both positive bacilloscopy and positive anti-PGL-1 IgM serology. Positivity concordance between these two laboratorial exams (Kappa Index = 1; p < 0.001) was indicated, however, one case did not demonstrate concordance between the semiquantitative assessment of anti-PGL-1 IgM and the bacilloscopy index (Kappa Index = 0.96; p < 0.001). Among the 17 AHHC with positive bacilloscopy, eight were reassessed after prophylaxis with BCG and two of them presented negative anti-PGL-1 IgM serology, being these patients who had presented a bacilloscopy index of < 2[+] in the initial assessment. This study shows that anti-PGL-1 IgM detection may be used as a tool to determine the bacillary load in AHHC and to detect immune changes related to prophylaxis by nonspecific vaccination.

Leprosy exposure, infection and disease: a 25-year surveillance study of leprosy patient contacts

Contact surveillance is a valuable strategy for controlling leprosy. A dynamic cohort study of leprosy contacts was initiated in 1987 at Oswaldo Cruz Foundation. The objective of this work was to review the data on the major risk factors leading up to the infectious stage of the disease, estimate incidence rates of leprosy in the cohort and characterise the risk factors for the disease among the contacts under surveillance. The incidence rate of leprosy among contacts of leprosy patients was estimated at 0.01694 cases per person-year in the first five years of follow-up. The following factors were associated with acquiring the disease: (i) not receiving the BCG vaccine, (ii) a negative Mitsuda reaction and (iii) contact with a patient with a multibacillary clinical form of leprosy. The contacts of index patients who had high bacilloscopic index scores > 1 were at especially high risk of infection. The following factors were associated with infection, which was defined as a seropositive reaction for anti-phenolic glicolipid-1 IgM: (i) young age (< 20 years), (ii) a low measured Mitsuda reaction (< 5 mm) and (iii) contact with an index patient who had a high bacilloscopic index. BCG vaccination and re-vaccination were shown to be protective among household contacts. The main conclusions of this study indicate an urgent need for additional leprosy control strategies in areas with a high incidence of the disease.

Whole-blood nested-PCR amplification of M. leprae-specific DNA for early diagnosis of leprosy

We evaluated the sensitivity and specificity of a nested-polymerase chain reaction (PCR) method for detection of Mycobacterium leprae DNA from whole blood. Whole-blood specimens were subjected to nested-PCR amplification of M. leprae repeat DNA sequences in 49 multibacillary (MB) and 30 paucibacillary (PB) leprosy patients, 96 household contacts (HHCs), 18 tuberculosis (TB) patients, and 35 normal healthy individuals. M. leprae DNA was detected in 95.92% (47/49) of MB, 70% (21/30) of PB, and 6.25% (6/96) of HHC, but it was not detected in 18 TB or 35 normal controls. The sensitivities of the anti-bovine serum albumin (ND-O-BSA) immunoglobulin M (IgM) and antifusion protein of ML0405-ML2331 IgG for MB were 97.96% and 89.8%, and these values for PB were 70% and 53.33%. However, the ND-O-BSA enzyme-linked immunosorbent assay (ELISA) had lower specificity, with relatively high false-positive results for TB patients (16.67%) and normal healthy controls (10%). Based on these promising findings, we propose the use of nested PCR of whole-blood samples along with ELISA test for early detection of leprosy cases.

Leprosy serology using PGL-I: a systematic review

Serology using a species-specific antigen for Mycobacterium leprae, PGL-I, could be a marker for the bacterial load of patients with leprosy. Various studies have identified the potential use of serology in the classification of patients for treatment purposes, case monitoring, identification of the risk of relapse and selection of household contacts with a higher risk of contracting the disease. A systematic review of the literature was conducted and 26 articles were included in this comparative analysis. The results of the use of PGL-I serology in different situations, its limitations and possible applications were evaluated. Studies show the efficacy of PGL-I serology in the classification of patients, treatment monitoring and as a predictive test for leprosy reactions. To improve early diagnosis and follow-up of the population at greatest risk of developing leprosy, the methodologies used in the past have yet to show a favorable cost-benefit ratio, although studies indicate that the use of the test might positively influence leprosy control programs. With simple and robust techniques, the use of PGL-I serology is viable.

Positividade sorológica antiPGL-I em contatos domiciliares e peridomiciliares de hanseníase em área urbana

FUNDAMENTOS: Pesquisas atuais buscam avaliar a prevalência de pessoas infectadas pelo M. leprae, bem como o valor preditivo dos testes utilizados, em meio aos quais está a sorologia, que detecta anticorpos contra um antígeno específico da parede do Mycobacterium leprae, o glicolipídio fenólico (PGL-I). OBJETIVOS: Conhecer a taxa de infecção em contatos intra e peridomiciliares, e a relação de soropositividade com sexo, idade e grupo multibacilar/paucibacilar. MATERIAIS E MÉTODOS: Inquérito soroepidemiológico em contatos domiciliares e peridomiciliares dos casos notificados como hanseníase entre 1998 e 2002, no segundo distrito do Município de Duque de Caxias, RJ, utilizando o teste sorológico rápido de fluxo lateral ou ML Flow. RESULTADOS: Em 390 domicílios de casos de hanseníase foram identificados 2.130 contatos, e submetidos à sorologia 1.866 (12,4% de perda). A soropositividade foi de 15,7% (292/1.866), sendo 15,8% no domicílio e 15,6% no peridomicílio. Também não houve diferença na relação entre soropositividade e sexo e em maiores e menores de 15 anos. Observou-se diferença significativa na soropositividade de contatos de casos de hanseníase MB (67,5%), duas vezes maior do que a dos casos de PB (32,5%). DISCUSSÃO / CONCLUSÃO: Nas condições de moradia da periferia urbana de área endêmica devem ser submetidos igualmente à vigilância epidemiológica os contatos domiciliares e peridomiciliares.

S, Gonçalves OS, Lessa ZL, Rotta O. Sorologia Anti PGL-1 e risco de ocorrência de hanseníase em área de alta endemicidade do Estado de São Paulo: quatro anos de seguimento

Os testes sorológicos para diagnóstico de hanseníase, usando o glicolipídeo-fenólico-1 (PGL-1), considerado antígeno específico do M. leprae, têm aberto algumas possibilidades de estudo do comportamento epidemiológico desta doença. Algumas questões, como tempo de latência da doença, infecção subclínica e importância do contato intra-domiciliar (contatos) no controle da endemia, puderam ser melhor analisadas usando este instrumental. Este estudo teve por objetivo verificar a existência de associação entre a situação sorológica e a ocorrência de hanseníase. Foram seguidas, durante 4 anos, 6.520 pessoas com idade igual ou superior a 5 anos, submetidas no início do seguimento ao teste sorológico Anti PGL-1, pertencentes ao universo de 7.416 habitantes da área urbana de um município paulista caracterizado por elevada endemicidade de hanseníase. Foi identificado um grupo de 590 indivíduos soropositivos (9,0 %). Foram diagnosticados, no período, 82 casos novos de hanseníase, 26 no grupo de soropositivos (441 casos novos/10.000 indivíduos) e 48 no de soronegativos (81/10.000). Entre os que não fizeram sorologia, surgiram 8 casos novos (89/10.000). Procurou-se controlar, na análise, a condição de contato, dado que a taxa de soropositividade padronizada por idade e sexo era de 9,61% no grupo de contatos e 7,65% no de não-contatos. Tomando-se os não-contatos soronegativos como o grupo de "não expostos", foram calculados os riscos relativos de adoecimento no período, a partir das taxas de detecção padronizadas por idade, resultando no seguinte: os contatos ID soropositivos apresentaram a taxa de 1.704/10.000, 27 vezes maior que a dos "não-expostos", igual a 63/10.000; os não-contatos soropositivos e os contatos soronegativos apresentaram taxas, respectivamente, de 274 e 198/10.000, ambas maiores que as dos "não-expostos" e iguais entre si. A soropositividade associou-se à elevação de 8,6 vezes do risco de hanseníase entre os contatos e de 4,4 entre os não-contatos. Na situação epidemiológica estudada, caracterizada por elevada endemicidade de hanseníase, 50% dos casos novos surgiram entre os não-contatos soronegativos, ou seja, sem fonte de infecção conhecida. Portanto, o teste anti-PGL-1 usado revela-se, na prática, de pouca aplicabilidade. Resta estudar ainda o comportamento da sorologia anti-PGL-1 em áreas de média e baixa endemicidade para que se possa tirar conclusões mais consubstanciadas sobre sua utilidade no controle da endemia. Recomenda-se o aprofundamento das pesquisas sorológicas e de outras que aprimorem o diagnóstico precoce da infecção subclínica, inclusive para detecção de formas paucibacilares, para se ampliar as possibilidades de influir no controle endêmico.

Alocação do paciente hanseniano na poliquimioterapia: correlação da classificação baseada no número de lesões cutâneas com os exames baciloscópicos

FUNDAMENTOS: A integração das ações de controle da hanseníase às estratégias dos Programas de Saúde da Família e Agentes Comunitários de Saúde, na conformidade do processo de reorganização da atenção básica, fundamentou a atualização das normas da legislação sobre o controle da doença no Brasil. A classificação operacional adotada, para alocação do paciente na poliquimioterapia, foi adaptada da sugerida pela Organização Mundial de Saúde, essencialmente clínica, baseada no número de lesões cutâneas. De acordo com essa recomendação, são considerados paucibacilares (PB) os casos com até cinco lesões e multibacilares (MB) os com mais de cinco lesões cutâneas.O que se discute é a validade desse método de classificação, que toma como referência apenas aspectos clínicos. OBJETIVOS: Avaliar o método clínico de classificação baseado no número de lesões cutâneas correlacionando-o com os resultados dos exames baciloscópicos de esfregaços da pele. MÉTODOS: A fonte de informações foi o banco de dados no qual são registradas informações clínicas, epidemiológicas e laboratoriais dos pacientes. Foram selecionados 837 registros do período de 1986 a 1999, e os critérios avaliados foram o número de lesões cutâneas e o resultado do exame baciloscópico, ambos no momento do diagnóstico. Estabeleceu-se a comparação e calcularam-se a sensibilidade e especificidade relativa e os valores preditivo positivo e negativo do critério lesão cutânea e determinou-se a concordância entre o número de lesões e a baciloscopia por meio do cálculo do índice Kappa (k). RESULTADOS: Dos 837 casos avaliados, 652 apresentavam baciloscopias positivas, e 185, negativas. Dos positivos, 68 (11.4%) apresentavam menos de cinco lesões, e dos negativos 30 (16.0%) apresentavam mais de cinco lesões cutâneas. A sensibilidade e a especificidade do critério clínico foram de 89.6% e de 83.8% respectivamente, e o valor preditivo positivo de 95.1%, e o negativo de 69.5%. CONCLUSÃO: o método clínico baseado no número de lesões cutâneas para classificação dos pacientes hansenianos apresenta limitações que não invalidam sua operacionalidade, porém novos critérios devem ser desenvolvidos possibilitando uma melhor acurácia na alocação dos pacientes nos esquemas poliquimioterápicos.

Humoral immunity in Hansen's disease

For many years immune response in leprosy has been studied. Since 1960 several reports dealing with humoral immunity have been described in the literature. Different autoantibody rates occur in leprosy. There is an increase in the prevalence of autoantibodies in elderly patients with long standing disease, in lepromatous leprosy and in those with reactional states. The differences in rates among various studies are attributed to different methods and variations among patient samples concerning age, gender, polar forms, therapy and other elements. The prevalence of numerous antibodies, immune complexes, cryoglobulins and complement levels have been studied by many authors. This also highlights the importance of the more recent reviews of anti-Mycobacterium leprae glycolipid antibodies such as the anti-phenolic glycolipid-I antibodies in which titers are variable and depend on genetic factors.

Clinical usefulness of serological measurements obtained by antigen 60 in mycobacterial infections: development of a new concept

The humoral immune response occurring during mycobacterial infections was analysed with an ELISA test based on antigen 60. With tuberculosis, IgM antibodies indicate a primo-infection or a process of reactivation while IgG determinations allow an evaluation of the intensity of the infectious process. The test is also applicable to extrapulmonary tuberculosis, provided its sensitivity be adapted to these particular cases. This is particularly clear for tuberculous meningitis. The test is not species-specific and allows the detection of antibodies in atypical mycobacterioses and in leprosy patients. The final differentiation must be done by clinical examinations and cultures. In leprosy patients, IgM antibodies are detected nearly as frequently as IgG antibodies. In HIV-seropositive patients, the A60 seropositivity is correlated with a reactivation of former tuberculous infections and with primary tuberculous infections. At the AIDS stage, the A-60 seropositivity is due to atypical mycobacteria, with a better IgM than IgG response. Healthy people are negative in serology: the positive cases observed are due to inapparent infections gained by contact with an infectious focus. The seropositive cases observed in non-tuberculous hospitalized patients are restricted to some disease types, essentially lung infections (cystic fibrosis, cancer pneumopathies, sarcoidosis). Some patients have low levels of antibodies. This anergy may be traced to the formation of immune complexes or else to a weak avidity of the specific antibodies produced. This test should not be considered to be a diagnostic tool by itself. It should be used in conjunction with other diagnostic means that, together, allow the determination of a diagnosis.