Abstract
Hansen's disease (leprosy) remains an important health problem in Brazil, where 34,894 new cases were diagnosed in 2010, corresponding to 15.3% of the world's new cases detected in that year. The purpose of this study was to use home visits as a tool for surveillance of Hansen's disease in a hyperendemic area in Brazil. A total of 258 residences were visited with 719 individuals examined. Of these, 82 individuals had had a previous history of Hansen's disease, 209 were their household contacts and 428 lived in neighboring residences. Fifteen new Hansen's disease cases were confirmed, yielding a detection rate of 2.0% of people examined. There was no difference in the detection rate between household and neighbor contacts (p = 0.615). The two groups had the same background in relation to education (p = 0.510), household income (p = 0.582), and the number of people living in the residence (p = 0.188). Spatial analysis showed clustering of newly diagnosed cases and association with residential coordinates of previously diagnosed multibacillary cases. Active case finding is an important tool for Hansen's disease control in hyperendemic areas, enabling earlier diagnosis, treatment, decrease in disability from Hansen's disease and potentially less spread of Mycobacterium leprae.
Highlights
Hansen’s disease, as leprosy is called in Brazil, is an infectious disease of insidious onset, caused by Mycobacterium leprae. [1,2,3] Transmission is thought to occur primarily via the airborne route from people with multibacillary disease
A great challenge to disease control is the identification of people at risk of infection and development of disease. [4,5,6] Time between infection and disease development can vary and be five or more years after exposure; this makes interruption of transmission more challenging and it is difficult to identify areas at highest risk. [7,8,9] In endemic areas, the majority of individuals infected with M. leprae do not develop disease, [10;11] and it is believed that disease development is associated with close and prolonged contact with untreated people with multibacillary disease, [12;13] as well as genetic [14,15,16] and socioeconomic factors. [17;18]
The introduction of multidrug therapy (MDT) in 1981 resulted in a drastic shift in the global distribution of Hansen’s disease, and has been responsible for a significant decrease in new case detection in the past few decades. [21,22] Despite this advance, Hansen’s disease continues to be endemic in many countries, including Brazil, which has the second highest detection rate worldwide, [23] 1.54 cases/ 10,000 inhabitants. [24;25] Rio Grande do Norte (RN), a state located in the northeast of Brazil, has traditionally had a lower case detection rate than neighboring states, yet an increase in new case detection during the last decade has been documented. [26]
Summary
Hansen’s disease, as leprosy is called in Brazil, is an infectious disease of insidious onset, caused by Mycobacterium leprae. [1,2,3] Transmission is thought to occur primarily via the airborne route from people with multibacillary disease. [4,5,6] Time between infection and disease development can vary and be five or more years after exposure; this makes interruption of transmission more challenging and it is difficult to identify areas at highest risk. A significant challenge to interruption of transmission of M. leprae by early diagnosis of Hansen’s disease is that initial skin lesions can be very discrete and asymptomatic. For this reason, different strategies for case finding have been investigated. Hoeven et al (2008) identified an area with radius of 10 meters from the index case as being the highest risk for development of Hansen’s disease. The introduction of multidrug therapy (MDT) in 1981 resulted in a drastic shift in the global distribution of Hansen’s disease, and has been responsible for a significant decrease in new case detection in the past few decades. [21,22] Despite this advance, Hansen’s disease continues to be endemic in many countries, including Brazil, which has the second highest detection rate worldwide, [23] 1.54 cases/ 10,000 inhabitants. [24;25] Rio Grande do Norte (RN), a state located in the northeast of Brazil, has traditionally had a lower case detection rate than neighboring states, yet an increase in new case detection during the last decade has been documented. [26]
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