Questions about wildlife and potential health concerns often lead to misunderstandings, especially regarding whether possums carry leprosy. This article clarifies the scientific facts about leprosy and its connection to these animals.
The Truth About Possums and Leprosy
North American opossums, specifically Didelphis virginiana, are not considered significant carriers or natural reservoirs of Mycobacterium leprae, the bacterium responsible for most human leprosy cases. While some broader “possum” populations in other parts of the world, such as Brazil, have shown evidence of M. leprae, this does not typically extend to the opossums found across North America. Studies examining North American opossums for M. leprae have largely yielded negative results, indicating they do not play a substantial role in human leprosy transmission. In contrast, nine-banded armadillos are recognized as natural carriers of M. leprae in some southern U.S. regions. This distinction is important, as armadillos carry the disease, but North American opossums do not.
Distinguishing Leprosy-Causing Bacteria
Leprosy in humans is primarily caused by the bacterium Mycobacterium leprae, an organism that largely affects the skin and peripheral nerves. However, another distinct bacterial species, Mycobacterium lepromatosis, has also been identified as a cause of leprosy, including a severe form. While clinically indistinguishable from M. leprae infections, M. lepromatosis represents a separate lineage, having diverged millions of years ago. While M. lepromatosis has been detected in some wild animals, such as red squirrels in the United Kingdom, it is genetically distinct from M. leprae.
Transmission and Human Health
Human leprosy is primarily transmitted through prolonged and close contact with an untreated person who has the disease. The bacteria spread via respiratory droplets from the nose and mouth, typically when an infected individual coughs or sneezes. Leprosy is not easily spread through casual contact, such as shaking hands, hugging, or sharing meals.
The risk of contracting M. leprae from wild animals, including North American opossums, is extremely low. While armadillos are an exception, with documented cases of M. leprae transmission to humans, this typically occurs through direct handling or consumption of undercooked meat. The vast majority of people, around 95%, are naturally resistant to the bacteria that cause leprosy, meaning their immune systems can effectively fight off the infection even if exposed.
Coexisting Safely with Wildlife
Interacting with any wild animal carries inherent risks, and it is always advisable to maintain a respectful distance. Observing wildlife from afar helps ensure both human and animal safety.
It is important to never attempt to feed, touch, or handle wild animals, as this can lead to unpredictable behaviors and injury. Keeping domestic pets vaccinated and supervised, especially when outdoors, reduces their exposure to diseases that might circulate among wildlife.
Should an animal appear sick, injured, or behave unusually, the appropriate action is to contact local animal control or wildlife authorities rather than approaching it directly. These general precautions promote a safer coexistence between humans and all forms of wildlife.