The nine-banded armadillo (Dasypus novemcinctus) is a unique mammal with an armored shell that has significantly expanded its range across the southern and eastern United States. The presence of these animals in residential areas often raises concerns about potential disease transmission to humans and pets. Armadillos, like all wild mammals, can naturally host various bacteria, fungi, and parasites, making them a subject of public health interest in the regions they inhabit. Understanding which pathogens they carry requires looking closely at the specific biology of this animal.
Armadillos and Chlamydia
The question of armadillos carrying Chlamydia is often raised due to the notoriety of this bacterial family. The genus Chlamydia includes several species that cause disease in a wide range of hosts, from livestock and birds to humans. The strain most commonly associated with sexually transmitted infection in humans is Chlamydia trachomatis, which is a strict human pathogen.
The strain that is a frequent concern in veterinary medicine is Chlamydia pecorum, a different species that commonly affects livestock like cattle and sheep, as well as marsupials such as the koala. Scientific literature does not strongly establish the nine-banded armadillo as a common reservoir for this or other zoonotic Chlamydia strains. The bacteria in the Chlamydiaceae family are obligate intracellular parasites, meaning they must live inside a host cell to replicate.
The concern often stems from confusion between the distinct species within the large Chlamydia family. The lack of documented evidence linking Dasypus novemcinctus to the specific strains that cause human venereal disease is an important distinction. The pathogen most uniquely associated with this species of armadillo is a completely different type of bacteria altogether.
The Connection to Hansen’s Disease
The nine-banded armadillo holds a unique place in disease ecology because it is the only non-human animal known to naturally harbor the bacterium Mycobacterium leprae. This organism is the causative agent of Hansen’s disease, historically known as leprosy. The armadillo’s susceptibility is primarily due to its unusually low core body temperature, which ranges from 86 to 95 degrees Fahrenheit (30 to 35 degrees Celsius).
Mycobacterium leprae grows extremely slowly and thrives best in these cooler temperatures, particularly affecting peripheral nerves and the cooler extremities of the host. In some wild armadillo populations in the southern United States, the prevalence of the infection can be substantial, sometimes exceeding 20 percent. The infection in armadillos is considered a zoonosis, meaning it can transmit from animals to humans, though the risk remains low for the general public.
Transmission to humans is rare and is typically linked to prolonged, direct contact with an infected armadillo, such as handling the animal or consuming its undercooked meat. Studies have found that some indigenous cases of Hansen’s disease in the US share an identical strain of the bacteria with local armadillos, confirming the animal-to-human transmission pathway. This risk is largely concentrated in the Gulf Coast states, including Texas, Louisiana, and Florida, where armadillo interaction is more frequent.
Other Potential Health Hazards
Beyond Hansen’s disease, armadillos can carry several other pathogens, though the risk of transmission to humans is generally low and often indirect. One common bacterial concern is Salmonella, which can be present in the armadillo’s digestive tract and shed through its feces. Contamination of soil or water by droppings can pose a risk, especially if humans or pets come into contact with the contaminated area.
Armadillos may also carry Leptospira bacteria, which causes Leptospirosis, a disease that can affect the liver and kidneys in humans. This bacteria is typically shed in the urine of infected animals and can survive in water or moist soil for extended periods.
Armadillos can also be involved in the life cycles of certain parasites, such as the protozoan Trypanosoma cruzi, which causes Chagas disease in Central and South America. Fungal infections, such as those causing Histoplasmosis, are another hazard, as the fungus Histoplasma capsulatum thrives in soils enriched with animal droppings. While rare, armadillos are theoretically capable of contracting and transmitting the rabies virus, although documented cases are extremely infrequent compared to other wildlife species like raccoons or bats.
Reducing Transmission Risk
The primary way to reduce the risk of disease transmission from armadillos is to avoid all direct contact with the animals and their bodily fluids. The nine-banded armadillo is not naturally aggressive, so most human infection occurs during attempts to capture, handle, or clean the animal’s carcass. Never attempt to handle a live or dead armadillo, particularly if it appears sick, injured, or is lethargic during the daytime.
If an armadillo has been in your yard or property, practice proper hygiene by thoroughly washing hands after gardening or performing other outdoor activities. Prevent pets from interacting with armadillos or their burrows to minimize the potential for exposure to bacteria, parasites, and fungi. For those in regions where armadillos are hunted, wearing protective gloves when dressing the animal and ensuring the meat is cooked to a high internal temperature are effective measures to destroy any lingering pathogens.