Leprosy, now officially known as Hansen’s disease, is a chronic bacterial infection caused by the slow-growing bacterium Mycobacterium leprae. This bacterium primarily targets the peripheral nerves, skin, and upper respiratory tract. While many people associate the disease with ancient history, it remains a current public health concern in many parts of the world. The disease is curable with multi-drug therapy, but delayed diagnosis can lead to permanent nerve damage and disability. This article clarifies the connection between Hansen’s disease and the nine-banded armadillo.
The Direct Answer: Is Transmission Possible?
Yes, transmission of Mycobacterium leprae from armadillos to humans is possible, making it a zoonotic disease in the United States. This occurrence is rare, given that approximately 95% of the human population possesses a natural immunity. The US sees about 150 to 250 new cases of Hansen’s disease annually, though a significant portion are linked to international travel. DNA evidence confirms that a unique strain of the bacteria found in some US patients is genetically identical to the strain carried by local armadillos. This domestic transmission risk is concentrated in the southern United States, specifically in the Gulf Coast states such as Texas, Louisiana, Florida, and Mississippi.
Armadillos as Unique Carriers
The nine-banded armadillo is the only known animal reservoir for M. leprae in the US, and one of the few species worldwide that can sustain a natural infection. This unusual susceptibility is tied to the animal’s unique physiology. The bacteria thrives at temperatures lower than the typical human body temperature of 37°C. The armadillo’s average body temperature, which ranges from 32°C to 35°C, provides an ideal environment for the bacteria to multiply. In some southern regions, up to 20% of the wild armadillo population may harbor the bacterium.
Routes of Zoonotic Transmission
The transfer of M. leprae requires close and sustained contact with an infected armadillo. The primary mechanism involves direct handling of the animal, its tissues, or its blood, often occurring when people hunt or attempt to capture the animal. The bacteria are also shed through nasal secretions, meaning that inhaling droplets or contacting contaminated surfaces poses a risk. A less common, yet documented, route of exposure is the consumption of armadillo meat that has been improperly cooked. Some researchers also suggest that contact with soil contaminated by an infected armadillo’s secretions may be a potential route of transmission.
Practical Steps for Prevention
The most effective way to prevent armadillo-related Hansen’s disease is to avoid all direct contact with the animals. People living in areas where armadillos are common should not attempt to capture, touch, or keep these wild animals as pets. This avoidance extends to sick or deceased armadillos, as handling their carcasses presents a significant exposure risk.
Hygiene and Handling
If handling an armadillo is necessary, such as for removal from a property, one should wear thick, durable gloves and protective clothing. Following any potential contact with an armadillo or the soil it inhabits, thorough hand washing with soap and water is an important hygiene measure. For those who consume armadillo meat, ensuring it is cooked to a well-done internal temperature dramatically reduces the risk of bacterial survival.
Recognizing Symptoms
Since Hansen’s disease symptoms can take years to appear, a high index of suspicion is appropriate following confirmed armadillo exposure. Symptoms may include persistent skin lesions that are often lighter in color or reddish. Another element is areas of the skin with numbness or loss of sensation. Anyone who has had close exposure and notices these signs should seek medical consultation, as early detection and treatment prevent the disease from progressing to cause permanent nerve damage.