Safety and efficacy assessment of two new leprosy skin test antigens: randomized double blind clinical study

BACKGROUND

New tools are required for the diagnosis of pre-symptomatic leprosy towards further reduction of disease burden and its associated reactions. To address this need, two new skin test antigens were developed to assess safety and efficacy in human trials.

METHODS

A Phase I safety trial was first conducted in a non-endemic region for leprosy (U.S.A.). Healthy non-exposed subjects (n = 10) received three titrated doses (2.5 µg, 1.0 µg and 0.1 µg) of MLSA-LAM (n = 5) or MLCwA (n = 5) and control antigens [Rees MLSA (1.0 µg) and saline]. A randomized double blind Phase II safety and efficacy trial followed in an endemic region for leprosy (Nepal), but involved only the 1.0 µg (high dose) and 0.1 µg (low dose) of each antigen; Tuberculin PPD served as a control antigen. This Phase II safety and efficacy trial consisted of three Stages: Stage A and B studies were an expansion of Phase I involving 10 and 90 subjects respectively, and Stage C was then conducted in two parts (high dose and low dose), each enrolling 80 participants: 20 borderline lepromatous/lepromatous (BL/LL) leprosy patients, 20 borderline tuberculoid/tuberculoid (BT/TT) leprosy patients, 20 household contacts of leprosy patients (HC), and 20 tuberculosis (TB) patients. The primary outcome measure for the skin test was delayed type hypersensitivity induration.

FINDINGS

In the small Phase I safety trial, reactions were primarily against the 2.5 µg dose of both antigens and Rees control antigen, which were then excluded from subsequent studies. In the Phase II, Stage A/B ramped-up safety study, 26% of subjects (13 of 50) showed induration against the high dose of each antigen, and 4% (2 of 50) reacted to the low dose of MLSA-LAM. Phase II, Stage C safety and initial efficacy trial showed that both antigens at the low dose exhibited low sensitivity at 20% and 25% in BT/TT leprosy patients, but high specificity at 100% and 95% compared to TB patients. The high dose of both antigens showed lower specificity (70% and 60%) and sensitivity (10% and 15%). BL/LL leprosy patients were anergic to the leprosy antigens.

INTERPRETATION

MLSA-LAM and MLCwA at both high (1.0 µg) and low (0.1 µg) doses were found to be safe for use in humans without known exposure to leprosy and in target populations. At a sensitivity rate of 20-25% these antigens are not suitable as a skin test for the detection of the early stages of leprosy infection; however, the degree of specificity is impressive given the presence of cross-reactive antigens in these complex native M. leprae preparations.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01920750 (Phase I), NCT00128193 (Phase II).

Occurrence of soil-transmitted helminths in women at the Himalayan region of Nepal

OBJECTIVE

To find the occurrence pattern and prevalence of the soil transmitted helminths in women of child bearing age group.

METHODS AND MATERIALS

The study was conducted in Jiri , an area of Dolakha district at the altitude of 2100 meter from sea level. The faecal sample of 478 women of childbearing age (15 to 45 years) were taken randomly and examined for the ova of soil transmitted helianthus.

RESULT

The occurrence pattern was 53.0%, 20.0% and 2.7% for Hookworms, Ascaries lumbricoids and Trichuris Trichuria respectively. Both Ascaries and Hookworm prevalence rates noticeably increased with increasing age, with the highest infection rate between the age of 36-45 years while trichuris infection reached the highest in women of 15-25 years of age.

CONCLUSION

There is a high prevalence of hookworm and ascaries in women of childbearing age and necessary intervention is needed according to WHO guidelines.

Trend of blood group distribution among the Jirels of Nepal

This study was undertaken to find out the trend of blood group distribution among the Jirels, a small tribe, descended from Kirat tribe and to compare with other castes within Nepal and with people of other continents. Blood group distribution (ABO grouping and Rh typing) was studied among 2093 Jirels (Male-1057 and Female-1036). The frequency of distribution of A, B, O and AB was 55.05%, 14.72%, 21.64% and 8.6% respectively. The group A was found to be most common among the Jirels where as O is most common in the world. Only 0.14%of the Jirels were was found to be Rhesus Negative (Rh -ve).