Abstract
Mycobacterium leprae (M. leprae) is a human pathogen and the causative agent for leprosy, a chronic disease characterized by lesions of the skin and peripheral nerve damage. Zoonotic transmission of M. leprae to humans by nine-banded armadillos (Dasypus novemcinctus) has been shown to occur in the southern United States, mainly in Texas, Louisiana, and Florida. Nine-banded armadillos are also common in South America, and residents living in some areas in Brazil hunt and kill armadillos as a dietary source of protein. This study examines the extent of M. leprae infection in wild armadillos and whether these New World mammals may be a natural reservoir for leprosy transmission in Brazil, similar to the situation in the southern states of the U.S. The presence of the M. leprae-specific repetitive sequence RLEP was detected by PCR amplification in purified DNA extracted from armadillo spleen and liver tissue samples. A positive RLEP signal was confirmed in 62% of the armadillos (10/16), indicating high rates of infection with M. leprae. Immunohistochemistry of sections of infected armadillo spleens revealed mycobacterial DNA and cell wall constituents in situ detected by SYBR Gold and auramine/rhodamine staining techniques, respectively. The M. leprae-specific antigen, phenolic glycolipid I (PGL-I) was detected in spleen sections using a rabbit polyclonal antibody specific for PGL-I. Anti-PGL-I titers were assessed by ELISA in sera from 146 inhabitants of Belterra, a hyperendemic city located in western Pará state in Brazil. A positive anti-PGL-I titer is a known biomarker for M. leprae infection in both humans and armadillos. Individuals who consumed armadillo meat most frequently (more than once per month) showed a significantly higher anti-PGL-I titer than those who did not eat or ate less frequently than once per month. Armadillos infected with M. leprae represent a potential environmental reservoir. Consequently, people who hunt, kill, or process or eat armadillo meat are at a higher risk for infection with M. leprae from these animals.
Highlights
The human pathogen, M. leprae, causes leprosy, a slowly developing chronic granulomatous disease mainly affecting the skin and peripheral nerves, resulting in disfiguring lesions and progressive nerve damage that can lead to muscle weakness or atrophy, bone loss, amputations and blindness [1]
Armadillos have been shown to be a natural reservoir of Mycobacterium leprae infection in the southern states of the U.S and have been implicated in the zoonotic transmission of leprosy to humans
We took samples of liver and spleen from armadillos to look for M. leprae infection in the tissues
Summary
The human pathogen, M. leprae, causes leprosy, a slowly developing chronic granulomatous disease mainly affecting the skin and peripheral nerves, resulting in disfiguring lesions and progressive nerve damage that can lead to muscle weakness or atrophy, bone loss, amputations and blindness [1]. Paraand the Amazon region have recorded some of the highest new case detection rates in the country, despite having one of the lowest population densities [5]. Reasons behind this have been well-documented, and include living in a hyperendemic area, low human development index (HDI, which combines life expectancy at birth, per capita income, and education level), living with an untreated index case or within 200 meters of a case, high household density (>2 people per bedroom), poor nutritional status, and lack of healthcare availability [6,7]
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