Leprosy cases in Florida have been rising, and the honest answer is that no single cause fully explains why. Nine-banded armadillos carry the bacterium and are a confirmed source of human infection in the southeastern United States, but many Florida patients have no history of armadillo contact. The picture is more complicated than the “armadillo disease” headlines suggest.
The Armadillo Connection
Nine-banded armadillos are the only known animal reservoir for the bacterium that causes leprosy. Research from the University of Florida’s Emerging Pathogens Institute found that roughly 16.5 percent of armadillos in southern Florida harbor the pathogen. In other southern states like Louisiana and Texas, whole-genome sequencing has confirmed that wild armadillos and locally infected patients carry the same genetic strain, establishing a clear zoonotic link.
Florida’s situation is different. While armadillo transmission is plausible, studies of Florida cases show no clear dominant risk factor. Many patients diagnosed in central Florida had no known armadillo exposure, and armadillos east of the Mississippi River carry the bacterium less frequently than those farther west. Researchers have cautioned that locally acquired cases in the eastern United States “should not be assumed to be from armadillos.”
Other Ways the Bacterium Spreads
Leprosy spreads primarily through prolonged, close contact with an untreated infected person, typically through respiratory droplets over months or years. International migration plays a meaningful role. Florida has large communities of people from countries where leprosy remains common, including Brazil, India, and parts of the Caribbean. Researchers have noted that close, prolonged contact with immigrant individuals, or with non-immigrant individuals who frequently travel to endemic regions, is a realistic pathway for local transmission.
There is also growing interest in whether the bacterium can survive in soil or water. Some scientists have proposed that it could be “environmentally mediated,” meaning people might pick it up from contaminated soil rather than from direct contact with an animal or another person. This could help explain cases in outdoor workers. One Florida case series described a construction worker diagnosed with leprosy who had a history of incarceration in Tampa and Miami facilities, and a nurse aide at a geriatric facility who denied both armadillo and known leprosy exposure. Neither case fit neatly into the armadillo theory or the person-to-person theory.
Why Most People Are Not at Risk
About 95 percent of people have natural immunity to the leprosy bacterium. Even with direct exposure, the vast majority of people’s immune systems eliminate it before it can take hold. The disease develops only in the small fraction of people whose immune response doesn’t clear the pathogen, and even then it progresses very slowly, sometimes taking 3 to 5 years or longer before symptoms appear.
Recognizing the Early Signs
Leprosy affects the skin and peripheral nerves. The earliest sign is usually a discolored or lighter patch of skin that feels numb to the touch. Other symptoms include firm, rounded bumps under the skin, thick or unusually dry skin, painless ulcers on the soles of the feet, and swelling or lumps on the face or earlobes. Some people lose eyebrows or eyelashes.
Because the bacterium attacks nerves, numbness and muscle weakness are hallmark features, particularly in the hands and feet. Enlarged nerves can sometimes be felt near the elbows, knees, or sides of the neck. Nasal symptoms like chronic stuffiness and nosebleeds also occur. Left untreated, nerve damage can become permanent, but the disease is fully curable with antibiotics.
How Leprosy Is Treated
Treatment uses a combination of three antibiotics taken together, a regimen the WHO calls multidrug therapy. Milder forms require about 6 months of treatment, while more advanced cases need 12 months. Once treatment begins, a person quickly becomes non-contagious. The combination approach prevents the bacterium from developing resistance, and relapse after completing the full course is rare.
The bigger challenge is diagnosis. Because leprosy is so uncommon in the United States, many doctors have never seen a case. Symptoms mimic other skin conditions, and the long incubation period means patients often can’t connect their symptoms to any particular exposure. In Florida, where cases are appearing without obvious risk factors, that diagnostic delay can stretch even longer.
Why Florida Stands Out
Florida consistently reports more locally acquired leprosy cases than most other states. The combination of a warm climate where armadillos thrive, a large population with ties to leprosy-endemic countries, and significant outdoor occupational exposure creates overlapping risk factors that don’t exist to the same degree elsewhere in the country. What makes the situation unusual is that researchers still cannot confidently attribute most Florida cases to a single transmission route. The state appears to have multiple pathways operating simultaneously, making it harder to pinpoint what any individual patient’s source of infection was.