Abstract
BACKGROUNDLeprosy is a chronic infectious disease caused by the obligate intracellular bacillus Mycobacterium leprae. Because leprosy diagnosis is complex and requires professional expertise, new tools and methodologies are needed to detect cases in early stages and prevent transmission. The M. leprae genome contains mce1A, which encodes a putative mammalian cell entry protein (Mce1A). We hypothesised that the presence of Mce1A on the cell surface could be detected by the host's immune system.OBJECTIVEThe aim of this study was to evaluate antibody responses against the Mce1A protein in leprosy patients, household contacts of patients, and the general population to present an addition tool for leprosy diagnosis.METHODSA cross-sectional study involving 89 volunteers [55 leprosy cases, 12 household contacts (HHC) and 22 endemic controls (EC)] was conducted at Couto Maia Hospital, in Salvador, Bahia (BA), Brazil.RESULTSThe median anti-Mce1A IgA was significantly higher in multibacillary (MB) and paucibacillary (PB) cases than in EC (p < 0.0001). A similar trend was observed in IgM levels, which were significantly higher in both MB (p < 0.0001) and PB (p = 0.0006) groups compared to in EC individuals. The greatest differences were observed for IgG class-specific antibodies against Mce1A. The median levels of MB and PB were significantly higher compared to both controls HHC and EC (MB or PB vs EC, MB vs HHC p < 0.0001; PB vs HHC, p = 0.0013). Among leprosy cases, IgG enzyme-linked immunosorbent assay sensitivity and specificity were 92.7% and 97.1%, respectively. IgG positivity was confirmed in 92.1% and 94.1% of MB and PB patients, respectively.CONCLUSIONThis novel diagnostic approach presents an easy, non-invasive, and inexpensive method for leprosy screening, which may be applicable in endemic areas.
Highlights
Leprosy is a chronic infectious disease caused by the obligate intracellular bacillus Mycobacterium leprae
A similar trend was observed in IgM levels, which were significantly higher in both MB (p < 0.0001) and PB (p = 0.0006) groups compared to in endemic controls (EC) individuals
Neuropathological involvement resulting in loss of peripheral motor function, and deformities are historically responsible for the social stigma associated with this disease (Eichelmann et al 2013)
Summary
A cross-sectional study involving 89 volunteers [55 leprosy cases, 12 household contacts (HHC) and 22 endemic controls (EC)] was conducted at Couto Maia Hospital, in Salvador, Bahia (BA), Brazil. Setting - A cross-sectional study was conducted at Couto Maia Hospital (HCM), a reference unit for the treatment of leprosy patients in Salvador, Bahia (BA), Brazil. After signing an informed consent form, volunteers were classified into three groups: leprosy cases, household contacts (HHC), and endemic controls (EC) (Table I). Skin smears were taken from four sites (both earlobes and elbows) and processed using the Ziehl-Neelsen staining technique to detect acid-fast bacilli by microscopy. Acid-fast bacilli were graded using a bacillary index (BI) according to the Ridley scale (0-6+) (MS 2010) and the average score of individual smears was recorded. Patients were stratified as either paucibacillary (PB), considered as up to five skin lesions and/or a negative BI, or multibacillary (MB) when they had more than five lesions and/or positive BI
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