Utility of recombinant proteins LID-1 and PADL in screening for Mycobacterium leprae infection and leprosy.

BACKGROUND: Despite the widespread use of multidrug therapy, leprosy remains an important public health concern in many regions. Detection is generally limited to clinical exam.

METHODS: As a two-tiered active case finding strategy, we used the LID-1 (leprosy IDRI diagnostic-1), and PADL (protein advances for the diagnosis of leprosy) antigens for serological examination of 2526 individuals randomly selected from 10 472 residents in a leprosy hyperendemic area (Cajazeiras, Paraiba, Brazil). Almost all seropositive (95%) and a subset of seronegative (17%) subjects then underwent clinical evaluations.

RESULTS: Prevalence of clinically apparent leprosy was 2.3% (19 cases among 834 fully examined individuals). LID-1 and PADL demonstrated a high sensitivity for supporting leprosy diagnosis at 89% and 87%, with positive predictive values (PPV) of 3.5% and 3.7%. The specificity for clinically apparent leprosy was low at 42% and 38%, respectively, and was likely reduced due to the presence of many asymptomatic individuals infected with Mycobacterium leprae.

CONCLUSIONS: Our data indicate the utility of the LID-1 and PADL antigens as primary screening tools for the detection of M. leprae infection and identification of leprosy patients. The follow-up of seropositive subjects could clarify the predictive value and utility of detecting anti-LID-1 and PADL antibodies within leprosy control programs.