ML Flow Test Research Articles

ML Flow serological test: complementary tool in leprosy

BackgroundThe evaluation of household contacts of leprosy cases allows the early diagnosis of new cases. ObjectiveTo 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. MethodsProspective 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. ResultsThere 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 limitationsDifficulty in convincing the contacts to undergo the evaluation and collection of the clinical sample. ConclusionThe 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.

Seroepidemiologic survey of the household contacts of leprosy patients.

Leprosy is a disabling infectious disease caused by Mycobacterium leprae. This study aimed to investigate the prevalence of leprosy among household contacts of leprosy patients. This study is a serological survey in household contacts of leprosy patients who had been treated or were undergoing treatment in the city of Presidente Prudente, São Paulo, Brazil, from 2006-2016, using clinical examination and screening for anti- Phenolic glycolipid-I antibodies with Mycobacterium leprae-flow serology. A total of 263 index cases of leprosy were identified during the study period. Of these, 53 were approached, and among their household contacts, 108 were examined. The ML-flow test was positive in 2 (1.85%) individuals, but clinical examination revealed no signs or symptoms of leprosy in them. Therefore, they were considered to have a subclinical infection. Leprosy was not confirmed in any household contacts. In this study, a lower percentage of household contacts, when compared to that in the literature, had a positive Mycobacterium leprae-flow test result. The use of Mycobacterium leprae-flow should be encouraged during the follow-up of at-risk populations, such as the household contacts of leprosy patients.

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

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. 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. 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. 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.

Serological and molecular detection of infection with Mycobacterium leprae in Brazilian six banded armadillos (Euphractus sexcinctus)

Leprosy was recognized as a zoonotic disease, associated with nine-banded armadillos (Dasypus novemcinctus) in the Southern United States of America in 2011. In addition, there is growing evidence to support a role for armadillos in zoonotic leprosy in South America. The current study evaluated twenty specimens of the six-banded armadillo (Euphractus sexcinctus), collected from rural locations in the state of Rio Grande do Norte (RN), Brazil for evidence of infection with Mycobacterium leprae. Serum was examined using two "in-house" enzyme-linked immunosorbent assays (ELISAs) and via two commercially available (ML flow and NDO-LID®) immunochromatographic lateral flow (LF) tests, for detection of the PGL-I and/or LID-1 antigens of the bacterium. The presence of M. leprae DNA in liver tissue was examined using the multi-copy, M. leprae-specific repetitive element (RLEP), as target in conventional and nested PCR assays. Molecular and anti-PGL-I-ELISA data indicated that 20/20 (100 %) of the armadillos were infected with M. leprae. The corresponding detection levels recorded with the LF tests were 17/20 (85 %) and 16/20 (85 %), for the NDO-LID® and ML flow tests, respectively. Our results indicate that, in common with D. novemcinctus, six banded armadillos (a species hunted and reared as a food-source in some regions of Brazil, including RN), represent a potential reservoir of M. leprae and as such, their role in a possible zoonotic cycle of leprosy within Brazil warrants further investigation.

Hot spots of leprosy in the endemic area of São Luís, Maranhão State, Northeastern Brazil

BackgroundDespite the decreasing of leprosy cases in Brazil, its occurrence remains high in certain Brazilian cities. The aim of the study was to analyze the spatial pattern of leprosy in São Luís, capital of Maranhão State, Northeastern Brazil. MethodologyAn ecological study was carried out based on secondary data from leprosy cases and contacts reported in the Notification of Injury Information System in2015, and information on residency domiciles in three districts in the city. ResultsA positive correlation was found between the leprosy cases and the average number of residents per household, and households with open sewage, garbage accumulated, with street identification, persons without income, dependents and the poor. A negative correlation between cases and households with a sidewalk, literate people and 60 years old or more were identified. The seropositivity of contacts examined using the ML Flow test was of 23.19%. The disease presents a heterogeneous spatial pattern, with hyperendemic clusters. ConclusionsThe spatialization of both leprosy cases and contacts and the identification of areas presenting the highest concentration of the disease in each district is important and constitutes an important tool to subsidize disease-control actions.

Performance of serological tests PGL1 and NDO-LID in the diagnosis of leprosy in a reference Center in Brazil

BackgroundEarly detection of leprosy and multidrug therapy are crucial to achieve zero transmission and zero grade II incapacities goals of World Health Organization. Leprosy is difficult to diagnose because clinical forms vary and there are no gold standard methods to guide clinicians. The serological rapid tests aid the clinical diagnosis and are available for field use. They are easy to perform, do not require special equipment or refrigeration and are cheaper than the molecular tests.MethodsWe evaluated the performance of two rapid serological tests (PGL1 and NDO-LID) in the discrimination of leprosy cases from healthy individuals at the Alfredo da Matta Foundation, a reference center for the disease in Manaus, Amazonas, Brazil. PGL1 and NDO-LID rapid tests are capable of detecting specific antibodies of M. leprae, IgM and IgM/IgG, respectively. A total of 530 healthy subjects and 171 patients (50 with paucibacillary and 121 multibacillary leprosy) were included in the study.ResultsAmong the paucibacillary leprosy patients, the sensitivity was 34.0 and 32.0% for the NDO-LID and PGL1, respectively. In multibacillary leprosy patients, the NDO-LID sensitivity was 73.6% and the PGL1 was 81.0%. Serological tests demonstrated specificities of 75.9% for PGL-1 and 81.7% for NDO-LID. The positive predictive value (PPV), negative predictive value (NPV) and accuracy in multibacillary patients were 47.9, 93.1, and 80.2% respectively for the NDO-LID, and 43.4, 94.6 76.8% for PGL1.ConclusionsThe tests showed limited capacity in the diagnosis of the disease, however, the high negative predictive value of the tests indicates a greater chance of true negatives in this group favoring exclusion of leprosy. This characteristic of the ML flow test is important in aiding clinical Diagnosis, especially in a region endemic to the disease and with other confounding skin conditions.

Multibacillary leprosy and the elderly: a field for further research

Introduction: Leprosy is an important public health problem in Brazil where 28,761 new cases were diagnosed in 2015 and 7.3% were among children, indicating active transmission. Objectives: This study was designed to analyse leprosy indicators in a Brazilian municipality (Mossoro, RN) and to identify the burden of Mycobacterium leprae infection among elderly residents using ML-Flow assay. Results: Leprosy continues to be hyperendemic in Mossoro and does not present signs of decline. However, both the general new case detection rate and the detection of MB cases were higher among 60–79 year olds. The percentage of new cases classified as MB increased progressively by age group and reached 67.7% among those with 60 or more years of age (180/266). A hyperendemic neighbourhood was selected for a diagnostic campaign and a total of 504 elderly individuals were tested with ML Flow test, which was strongly positive in four people (0.8%) and samples from skin biopsy of these subjects were also qPCR positive. Two new MB cases were confirmed, one of which had no cutaneous lesions. Conclusions: MB leprosy appears to be more frequent among the elderly regardless of whether the disease is experiencing or not a period of decline. According to our results and literature review we hypothesized that the greatest incidence of leprosy by age apparently is related to the life expectancy of the population. These characteristics suggest that active case finding campaigns for untreated MB leprosy among the elderly may be useful in endemic areas as an innovative complementary strategy to interrupt the transmission of M. leprae.

Evaluation of agreement between tests for the diagnosis of leprosy

ABSTRACT Introduction: Leprosy is a chronic infectious disease caused by the intracellular parasite Mycobacterium leprae. The diagnosis is essentially clinical, based on symptoms, skin exam, peripheral nerves and epidemiological history. Laboratory tests are carried out to complement the result of clinical diagnosis, or even serving as a confirmatory method. Objective: To investigate the positivity and agreement between skin smear, enzyme-linked immunosorbent assay (ELISA) with synthetic antigen ND-O-BSA, ML Flow test and polymerase chain reaction (PCR) for detection of Mycobacterium leprae in new cases of leprosy. Methods: We conducted a case series study assessing a convenience sample of 39 new cases of leprosy and a control group of 18 household contacts in Belem (PA) and in Igarape-Acu (PA) from March 2014 to September 2015. Results: The agreement between ELISA, ML Flow and PCR tests combinations showed slight to absent reproducibility (Kappa ≤ 0.24). The results showed greater sensitivity in PCR assay, with higher positivity in multibacillary cases. The ELISA test showed low positivity, even in multibacillary cases, resulting in no reaction to paucibacillary cases and household contacts. Conclusion: The high sensitivity of PCR decreases the agreement with other tests.

Can baseline ML Flow test results predict leprosy reactions? An investigation in a cohort of patients enrolled in the uniform multidrug therapy clinical trial for leprosy patients in Brazil.

BackgroundThe predictive value of the serology to detection of IgM against the Mycobacterium leprae-derived phenolic glycolipid-I/PGL-I to identify leprosy patients who are at higher risk of developing reactions remains controversial. Whether baseline results of the ML Flow test can predict leprosy reactions was investigated among a cohort of patients enrolled in The Clinical Trial for Uniform Multidrug Therapy for Leprosy Patients in Brazil (U-MDT/CT-BR).MethodsThis was a descriptive study focusing on the main clinical manifestations of leprosy patients enrolled in the U-MDT/CT-BR from March 2007 to February 2012 at two Brazilian leprosy reference centers. For research purposes, 753 leprosy patients were categorized according to a modified Ridley-Jopling (R&J) classification and according to the development of leprosy reactions (reversal reaction/RR and erythema nodosum leprosum/ENL), and whether they had a positive or negative bacillary index/BI.ResultsMore than half of the patients (55.5 %) reported leprosy reaction: 18.3 % (138/753) had a RR and 5.4 % (41/753) had ENL. Leprosy reactions were more frequent in the first year following diagnosis, as seen in 27 % (205/753) of patients, while 19 % (142/753) developed reactions during subsequent follow-up. Similar frequencies of leprosy reactions and other clinical manifestations were observed in paucibacillary (PB) and multibacillary (MB) leprosy patients treated with U-MDT and regular MDT (R-MDT) (P = 0.43 and P = 0.61, respectively). Compared with PB patients, leprosy reactions were significantly more frequent in MB patients with a high BI, and more patients developed RR than ENL. However, RR and neuritis were also reported in patients with a negative BI. At baseline, the highest rate of ML Flow positivity was observed in patients with a positive BI, especially those who developed ENL, followed by patients who had neuritis and RR. Among reaction-free patients, 81.9 % were ML Flow positive, however, the differences were not statistically significant compared to reactional patients (P = 0.45).ConclusionsMB and PB patients treated with R-MDT and U-MDT showed similar frequencies of RR and other clinical manifestations. Positive ML Flow tests were associated with MB leprosy and BI positivity. However, ML Flow test results at baseline showed limited sensitivity and specificity for predicting the development of leprosy reactions.Electronic supplementary materialThe online version of this article (doi:10.1186/s40249-016-0203-0) contains supplementary material, which is available to authorized users.

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

BackgroundThe 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.MethodsA 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.ResultsThe 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.ConclusionsThe 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.

Description of leprosy classification at baseline among patients enrolled at the uniform multidrug therapy clinical trial for leprosy patients in Brazil.

The uniform multidrug therapy clinical trial, Brazil (U-MDT/CT-BR), database was used to describe and report the performance of available tools to classify 830 leprosy patients as paucibacillary (PB) and multibacillary (MB) at baseline. In a modified Ridley and Jopling (R&J) classification, considering clinical features, histopathological results of skin biopsies and the slit-skin smear bacterial load results were used as the gold standard method for classification. Anti-phenolic glycolipid-I (PGL-I) serology by ML Flow test, the slit skin smear bacterial load, and the number of skin lesions were evaluated. Considering the R&J classification system as gold standard, ML Flow tests correctly allocated 70% patients in the PB group and 87% in the MB group. The classification based on counting the number of skin lesions correctly allocated 46% PB patients and 99% MB leprosy cases. Slit skin smears properly classified 91% and 97% of PB and MB patients, respectively. Based on U-MDT/CT-BR results, classification of leprosy patients for treatment purposes is unnecessary because it does not impact clinical and laboratories outcomes. In this context, the identification of new biomarkers to detect patients at a higher risk to develop leprosy reactions or relapse remains an important research challenge.

Presence of Mycobacterium leprae DNA and PGL-1 antigen in household contacts of leprosy patients from a hyperendemic area in Brazil.

Leprosy is a highly infectious disease endemic to underdeveloped countries. In Maranhão State, Northeastern Brazil, the hyperendemic rate of 56.11 cases/100,000 inhabitants increased the necessity of better understanding the epidemiological profile of this population, particularly regarding efficient methods for evaluating individuals residing with diagnosed patients to understand disease transmission and the risk of infection. In this study, we examined the percentage of contacts with positive indices for Mycobacterium leprae DNA and phenol-glycolipid-1 antigen (PGL-1). PGL-1 was analyzed by an enzyme-linked immunosorbent assay, the ML-Flow test, and polymerase chain reaction of oral and nasal secretions of 808 leprosy contacts from Maranhão. PGL-1 was detected in 14.0% of patients and differed by operational classification of the index case (P < 0.05). Seropositive results of ML-Flow were 15.0% and identified individuals with and without Bacillus Calmette-Guérin vaccine scars. Molecular diagnosis detected M. leprae DNA in 5.6% of oral samples and 4.6% of nasal tissues, and 87% of subjects resided with high bacillary load patients. This study reinforces the efficacy of combining molecular and serological techniques to identify potential bacillus carriers in the asymptomatic stage of infection, such as in household contacts, highlighting the importance of these meth-ods for monitoring hyperendemic populations.

Evaluation of a rapid serological test for leprosy classification using human serum albumin as the antigen carrier

The presence of anti-BSA antibodies may interfere in serological tests, as ELISA or immunochromatographic assays. BSA is frequently used as a blocking agent or as “inert” carrier of antigens, such as the NT-P-BSA, the semi-synthetic trisaccharide analogue of the PGL-I (phenolic glycolipid-I) antigen from the cell wall of the Mycobacterium leprae. PGL-I was prepared and linked to human serum albumin based in the hypothesis that replacing BSA by a human protein carrier would enhance the performance of leprosy serological tests. A total of 1162 serum samples were tested by ELISA and by the ML Flow rapid test using NT-P-BSA or NT-P-HSA antigens. When grouping leprosy patients as paucibacillary (PB) or multibacillary (MB) according to the Ridley & Jopling classification, ML Flow BSA and ML Flow HSA tests correctly allocated 70.9% and 68.6% of patients in the PB group, and 87% and 81% of patients in the MB group, respectively. Concordant results were found in 82.0% (953/1162) (kappa value=0.637; sd=0.023) of samples between ML Flow tests and 85.7% (996/1162) (kappa value=0.703; sd=0.021) between ELISA tests. ML Flow results were statistically similar and the same was true for ELISA tests using HSA or BSA. However, we noticed a tendency to decreased capacity to detect MB patients and an increased positivity among PB patients, HHC, TB patients and healthy controls by the HSA carrier in both ML Flow and ELISA. The PGL-I serology performed by the ML Flow test with BSA or HSA as antigen carriers can be a useful, friendly auxiliary tool to identify patients with higher bacterial load.

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.

Bacterial load in the nose and its correlation to the immune response in leprosy patients

Leprosy, whose etiologic agent is M. leprae, has its clinical manifestations correlated with distinct immunologic forms. The mechanism of infectivity and dissemination of the disease are not completely known, although the nasal mucosa is supposed to have an important role in pathogenesis. To correlate the clinical and bacteriological parameters with that of nasal biopsy and immunological tests, such as lepromin and ML-Flow results, in untreated leprosy patients. Two hundred and twenty-two patients were evaluated, clinically classified and subjected to skin smear, nasal biopsy, ML-Flow, and Mitsuda test. 689% of the cases were borderline cases. Nasal biopsy revealed 91.4% positivity in those who had specific antibodies against M. leprae on blood sample. Lepromatous leprosy cases were 100% positive on ML-flow test, had a large involvement in the nasal mucosa (91%), positive skin smears (100%) and negative Mitsuda test. Nasal bacillary index showed a good correlation with ML-Flow and had similar results when compared to skin smear. The tests agreement was good, revealing that nasal biopsy can be reliable in the diagnosis of multibacillary clinical forms and in the evaluation of the immunological status of leprosy patients. The presence of disseminated bacilli in the nasal mucosa was similar to skin involvement, when correlated with Mitsuda test and ML-Flow. As a result, the role of nasal bacillary index may play an important role in the clinical and immunologic characterization of leprosy patients.

Comparison of two rapid tests for anti-phenolic glycolipid-I serology in Brazil and Nepal

The diagnosis of leprosy continues to be based on clinical symptoms and early diagnosis and treatment are critical to preventing disability and transmission. Sensitive and specific laboratory tests are not available for diagnosing leprosy. Despite the limited applicability of anti-phenolic glycolipid-I (PGL-I) serology for diagnosis, it has been suggested as an additional tool to classify leprosy patients (LPs) for treatment purposes. Two formats of rapid tests to detect anti-PGL-I antibodies [ML immunochromatography assay (ICA) and ML Flow] were compared in different groups, multibacillary patients, paucibacillary patients, household contacts and healthy controls in Brazil and Nepal. High ML Flow intra-test concordance was observed and low to moderate agreement between the results of ML ICA and ML Flow tests on the serum of LPs was observed. LPs were "seroclassified" according to the results of these tests and the seroclassification was compared to other currently used classification systems: the World Health Organization operational classification, the bacilloscopic index and the Ridley-Jopling classification. When analysing the usefulness of these tests in the operational classification of PB and MB leprosy for treatment and follow-up purposes, the ML Flow test was the best point-of-care test for subjects in Nepal and despite the need for sample dilution, the ML ICA test yielded better performance among Brazilian subjects. Our results identified possible ways to improve the performance of both tests.

Comparison of three immunological tests for leprosy diagnosis and detection of subclinical infection

Our aim was to compare the performance of three serological assays in leprosy patients and their household contacts utilising two quantitative ELISA tests using native PGL-I (PGL-1 ELISA), synthetic ND-O-HSA (ND-O-HSA ELISA), and the semi-quantitative lateral flow test (ML Flow). Comparisons among three immunological assays, PGL-I ELISA, ND-O-HSA ELISA, and ML Flow were performed in 154 leprosy patients, 191 household contacts and 52 health subjects. The sensitivity results of the PGL-1, ND-O-HSA, and ML Flow were 68.83%, 63.84%, and 60.65%, respectively, with specificity of 98% for both ELISA assays. The native and synthetic PGL-I ELISA assays detected antibodies in 22.73% and 31.82% of the paucibacillary (PB) patients, respectively and the ML Flow test did not detect antibodies in this group. The ML Flow test was able to discriminate patients into PB or multibacillary (MB) forms, while the native PGL-I and ND-O-HSA was correlated with the bacillary load and the Ridley-Jopling clinical forms. In household contacts, the native PGL-I, ND-O-HSA, and ML Flow assays detected seropositivity of 25%, 17%, and 10%, respectively. The use of ELISA and ML Flow tests are thus recommended as additional tools in the diagnosis and classification of the clinical forms, aiding in prescribing the correct treatment regimen to prevent subsequent nerve damage and disability, and besides, the PGL-I ELISA may be used to detect subclinical infection in leprosy.

Uso do teste ML-Flow como auxiliar na classificação e tratamento da hanseníase

The treatment of leprosy is defined by the classification of patients as paucibacillary (PB) or multibacillary (MB). The WHO (World Health Organization) classifies patients according to the number of lesions, but Ridley-Jopling (R & J) also uses complementary exams, which are difficult to use outside reference services. In 2003, a test called ML-Flow, an alternative to Elisa serology, was developed to help classify patients as PB or MB and decide about their treatment. To assess the agreement between the ML-Flow test and slit skin smears, already largely used for MB detection, and to observe the efficacy of the ML-Flow test in the field. A retrospective study evaluating the medical records of 55 patients who had not undergone previous treatment, diagnosed as PB or MB according to R & J and subjected to slit skin smears and the ML- Flow test. In MB patients, slit skin smears were positive in 80% of the cases, the ML-flow was positive in 82.5%. Among PB patients, the ML-Flow was positive in 37.5% and slit skin smears were negative in 100% of the cases. The agreement between skin smear and ML-Flow results was 87.5%, with a kappa value of 0.59, p <0.001. No laboratory test is 100% sensitive and specific for the correct classification of all forms of leprosy. The ML-Flow test is faster, easier to use, and less invasive than slit skin smears and therefore may be useful when making therapeutic decisions in areas of difficult access to reference services.

Correlation between ELISA and ML Flow assays applied to 60 Brazilian patients affected by leprosy

Serological tests can be helpful in classifying leprosy patients as having either the paucibacillary or the multibacillary form. The aim of this study was to evaluate the concordance between two serological assays, i.e. ML Flow and ELISA, in a population of leprosy patients in Brazil. The investigation involved 60 patients with newly diagnosed leprosy. Together with the application of the serological assays, selected demographic, clinical and epidemiological data relating to the study population were recorded. ML Flow detected anti-PGL1 antibodies in 70% of the leprosy patients, while ELISA was positive in 53.3%. The degree of concordance between the tests was substantial (83.3%). A positive correlation was demonstrated between the results obtained in the semi-quantitative ML Flow test and ELISA absorbance values. We concluded that both serological assays were found to be efficient in detecting anti-PGL1 antibodies. The ML Flow test may be a cheaper and easier to perform alternative to ELISA in leprosy patients.

The additional benefit of the ML Flow test to classify leprosy patients

The use of the skin lesion counting classification leads to both under and over diagnosis of leprosy in many instances. Thus, there is a need to complement this classification with another simple and robust test for use in the field. Data of 202 untreated leprosy patients diagnosed at FIOCRUZ, Rio de Janeiro, Brazil, was analyzed. There were 90 patients classified as PB and 112 classified as MB according to the reference standard. The BI was positive in 111 (55%) patients and the ML Flow test in 116 (57.4%) patients. The ML Flow test was positive in 95 (86%) of the patients with a positive BI. The lesion counting classification was confirmed by both BI and ML Flow tests in 65% of the 92 patients with 5 or fewer lesions, and in 76% of the 110 patients with 6 or more lesions. The combination of skin lesion counting and the ML Flow test results yielded a sensitivity of 85% and a specificity of 87% for MB classification, and correctly classified 86% of the patients when compared to the standard reference. A considerable proportion of the patients (43.5%) with discordant test results in relation to standard classification was in reaction. The use of any classification system has limitations, especially those that oversimplify a complex disease such as leprosy. In the absence of an experienced dermatologist and slit skin smear, the ML Flow test could be used to improve treatment decisions in field conditions.