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.