Armadillos are distinctive mammals, recognized by their unique bony shells. These creatures, common in certain regions of the Americas, possess an unusual biological link to an ancient human disease: leprosy. This connection has become a significant area of scientific interest, shedding light on the disease’s transmission.
The Armadillo-Leprosy Link
Armadillos are the only animals, besides humans, known to naturally harbor Mycobacterium leprae, the bacterium that causes leprosy. The nine-banded armadillo (Dasypus novemcinctus), widely distributed across the southern United States and parts of South America, is the species primarily implicated.
The susceptibility of armadillos to M. leprae is attributed to their lower body temperature (32-35°C). This temperature range provides an optimal environment for the bacterium to multiply, unlike the higher core body temperatures of most other mammals. Genetic factors also contribute to their vulnerability, allowing the bacterium to establish and spread throughout their tissues. Not all armadillos carry the bacterium, but prevalence rates can be significant, ranging from 15% to 50% in some populations.
How Humans Can Contract It
Humans can contract M. leprae from armadillos through direct, prolonged contact with infected animals or their tissues. This includes activities like hunting, butchering, or frequent handling. While the bacterium can be found in an infected armadillo’s tissues, the risk of transmission to humans is generally low.
Despite potential zoonotic transmission, leprosy (Hansen’s disease) is not highly contagious between humans, and the risk from armadillos is low. Approximately 95% of people have natural immunity to the bacterium. If infection occurs, leprosy is curable with multidrug therapy, which eliminates the bacteria and prevents disease progression.
Steps to Reduce Risk
To minimize the potential for exposure to M. leprae from armadillos, individuals should avoid direct contact with these animals. This includes refraining from handling live or dead armadillos, especially those that appear sick or injured. If contact is unavoidable, such as during wildlife rehabilitation or removal efforts, wearing protective gloves is a recommended precaution.
For those who consume armadillo meat, thorough cooking is advised to eliminate any potential bacteria. The bacterium is fragile and does not survive well outside of a host or at high temperatures. Additionally, individuals in regions where armadillos are common should be aware of leprosy signs, such as unusual skin lesions or numbness. Seeking medical attention promptly after potential exposure, especially if symptoms develop, allows for early diagnosis and treatment.