Rapid quantitative serological test for detection of infection with Mycobacterium leprae, the causative agent of leprosy

Antigen-specific assessment of the immunological status of various groups in a leprosy endemic region

BACKGROUND

Serological tests can be important tools to assist in the diagnosis of leprosy and can contribute to an earlier diagnosis. The aim of this study was to evaluate the antibody responses against phenolic glycolipid-1 (PGL-1), natural disaccharide linked to human serum albumin via an octyl (NDO-HSA), Leprosy IDRI Diagnostic-1 (LID-1) and natural disaccharide octyl--Leprosy IDRI Diagnostic-1 (NDO-LID) in leprosy patients, household contacts of patients and the general population.

METHODS

Enzyme-linked immunosorbent assays were used to analyze the antigen-specific antibody responses of 94 leprosy cases, 104 household contacts of cases and 2.494 individuals from the general population.

RESULTS

A positive correlation was observed for the antibody responses to all antigens studied. A higher proportion of seropositivity for all antigens, along with stronger magnitude of response, was observed in multibacillary (MB) leprosy patients and household contacts of MB leprosy patients compared with the levels observed in paucibacillary (PB) leprosy patients and household contacts of PB leprosy patients. A substantial and significant positive correlation was found between seropositivity and the bacterial index for the leprosy patients. Anti-PGL-1 tests were more frequently positive than anti-NDO-HSA tests among patients with all clinical forms of leprosy and among the group of household contacts. The LID-1 and NDO-LID antigens showed a greater capacity to identify household contacts and individuals from the general population infected with M. leprae.

CONCLUSIONS

Tests that measure the antibody responses against LID-1, NDO-LID, NDO-HSA and PGL-1 were effective tools for the detection of patients with MB leprosy. Our data indicate that the anti-LID-1 and anti-NDO-LID responses were more effective than an anti-NDO-HSA response for the identification of individuals with subclinical infection.

Leprosy elimination: A myth busted

Background:

Leprosy is mainly a chronic infectious disease caused by Mycobacterium leprae. The disease mainly affects the skin, the peripheral nerves, mucosa of the upper respiratory tract and eyes. Though the target of leprosy elimination was achieved at national level in 2006 even then a large proportion of leprosy cases reported globally still constitute from India.

Aim and Objective:

To study the clinico-epidemiological profile of new cases of leprosy in a rural tertiary hospital.

Materials and Methods:

Thirty-five newly diagnosed cases of leprosy presented in out-patient/admitted in the department of Dermatology, Venereology and Leprosy (between September 2012 and August 2013) were included in the study. Detailed history regarding leprosy, deformity, sensory loss, skin smear for AFB and histopathological examination were done in every patient.

Results:

The incidence was more in age group of 20 to 39 years (48.57%) and 40 to 59 years (37.14%). 68.57% were males. 48.57% cases were found to have facial deformity and ear lobe thickening was found to be pre-dominant form of facial deformity. Ulnar (88.87%) and common peroneal nerve (34.28%) were the most commonly involved nerves. The split skin smear examination was found to be positive in 27 out of 35 cases. On histopathological examination 10 patients (28.57%) were of lepromatous pole (LL), 4 (11.43%) were of indeterminate, 6 (17.14%) were of tuberculoid type (TT), 4 BT (11.4%) and 1 BL type (2.8%).

Conclusions:

This study helps in concluding that leprosy is still not eliminated. Active surveillance is still needed to detect the sub-clinical cases and undiagnosed cases.

Evaluation of novel tools to facilitate the detection and characterization of leprosy patients in China

Leprosy is the disabling outcome of chronic infection with Mycobacterium leprae. The disease often evades early detection, particularly now that fewer clinicians are able to confidently diagnose the disease following the integration of leprosy control measures within general health services in many countries. Although leprosy is officially eliminated in China, endemic regions remain in some difficult-to-reach, underdeveloped areas in Southwest China. In order to better understand the extent of M. leprae infection and identify new leprosy cases in a timely manner, simple tools that can detect infection and the early disease are required. In this report we evaluated the performance of antigen-specific ELISA, the NDO-LID rapid diagnostic test, and antigen-specific whole blood assays (WBA) as potential diagnostic tools. Our data support the use of antibody detection tests and WBA to facilitate the diagnosis of multibacillary and paucibacillary leprosy, respectively. These tools could be invaluable for increased, but simplified, monitoring of individuals in order to provide referrals for clinical exam and early leprosy diagnosis.