Spatial and temporal epidemiology of Mycobacterium leprae infection among leprosy patients and household contacts of an endemic region in Southeast Brazil.

BACKGROUND

Leprosy is a chronic infectious disease that remains a public health problem in low- and middle-income countries. Household contacts of leprosy patients (HHCs) have increased risk of developing disease and are important links in the chain of transmission of Mycobacterium leprae. Based on epidemiological and operational factors, the global elimination strategy depends on the geographic stratification of endemic areas to intensify control activities. The purpose of the study was to integrate epidemiological indicators and serology into the spatial and temporal analysis of M. leprae infection, in order to understanding of the dynamics of transmission, essential information for the control of leprosy.

METHODOLOGY

Using location-based technologies and epidemiological data obtained from leprosy cases (N=371) and HHCs (N=53), during a 11year period (2004-2014), we explored the spatial and temporal distribution of diagnosed cases: stratified according their disease manifestation; and of subclinical infection among HHCs: determined by serology (anti-PGL-I ELISA and anti-NDO-LID rapid lateral-flow test); in order to assess the distribution pattern of the disease and the areas of greatest risk of illness, in a highly endemic municipality (Ituiutaba, MG) in the southeast region of Brazil.

RESULTS

Seropositivity among HHCs was: 17% (9/53) for anti-PGL-I ELISA; and 42% for the NDO-LID rapid lateral-flow test. Forty-nine percent of the contacts were seropositive to at least one of the immunological tests.

DISCUSSION

We observed substantial spatial heterogeneity of cases throughout the urban perimeter. Even so, four main clusters of patients and three main clusters of subclinical infection were identified.

CONCLUSIONS

Spatio-temporal epidemiology associated to serological assessment can identify high-risk areas imbedded within the overall epidemic municipality, to prioritize active search of new cases as well support prevention strategies in these locations of greater disease burden and transmission. Such techniques should become increasingly useful and important in future action planning of health interventions, as decisions must be made to effectively allocate limited resources.