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

Abstract

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.

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

“…Alternatively, the anti-PGL-I seropositivity among the contacts of multibacillary cases (18.2 %) is within the range of 16.9 to 23.9 % that has been reported in the literature. The lower seropositivity among the contacts of paucibacillary patients than the contacts of multibacillary patients has been observed in other studies [ 6 , 13 , 15 – 17 , 22 ]. That the highest seropositivity prevalence was detected among the contacts of multibacillary cases can be explained by the intensity of their exposure to bacillus because, at this stage, these patients contain a higher bacterial load.…”

“…Furthermore, a positive result on a serological test to identify antibodies to Mycobacterium leprae in individuals with no suggestive signs of disease can be used as a criterion to differentially monitor household contacts, as it is considered a potential indicator of the development of leprosy [ 21 ] and because individuals may undergo an extended period of bacillus proliferation before the onset of identifiable clinical signs [ 22 ].…”

Comprehensive measures succeeded in improving early detection of leprosy cases in post-elimination era: Experience from Shandong province, China

“…Leprosy, or Hansen's disease, caused by mycobacterium leprae, is a chronic infectious disease with a long incubation [1] and preferably affects skin and peripheral nerve systems [2]. If not treated timely, leprosy can result in permanent damage to peripheral nerves and may lead to amputations and disabilities [3].…”

Diagnostic accuracy of tests for leprosy: a systematic review and meta-analysis

“…Prompt diagnosis and treatment are the most important measures for leprosy control [4]. Clinical evaluation is the first step for leprosy diagnosis, which is generally sufficient for most cases; however, untrained health practitioners may not be effective in recognizing early signs of the disease [11,12]. In addition, a detailed dermatological and neurological examination can be timeconsuming, and the influence of social limitations (disease stigma and cultural restriction for complete skin examination) often jeopardizes an adequate evaluation.…”