A 4,000-year-old disease often associated with biblical times is making a slow but steady comeback in one U.S. state.
Leprosy, also known as Hansen’s disease, is an illness many often relegate to the history books. Florida, however, has recorded 17 infections this year as of July 18, according to state health data. Of the 174 cases recorded nationwide in 2025, 36 occurred in the state, including 27 that were contracted locally rather than abroad.
Hansen’s disease affects up to 225 people in the United States and 250,000 globally every year, according to the Centers for Disease Control and Prevention (CDC). While most cases are contracted abroad, the agency notes that Southern states have reported illnesses not linked to travel that were “likely contracted from armadillos.”
In the past decade, roughly 223 cases were recorded in Florida, the majority of which occurred in Brevard County. Central Florida, specifically, appears to be a recurring hotspot, accounting for 81% of state cases and almost one-fifth of nationally reported cases, according to research published in the CDC’s journal Emerging Infectious Diseases in 2023.
While it appears a pattern has emerged, scientists aren’t entirely sure why. The same 2023 report concluded that an increase in leprosy infections in non-foreign-born residents that “lacked traditional risk factors” indicated that the disease is probably now endemic in parts of the United States, with one cited case in a landscaper raising questions about environmental exposure.
And while it remains a rare ailment, the upward trend has been enough to draw attention. After peaking in early 1983, leprosy cases in the United States steadily declined until around the turn of the millennium, when they began increase again.
Hansen’s disease in U.S.: Scientists puzzled by rising leprosy in Florida
Leprosy can be disfiguring, especially to the skin on the face.
What is leprosy?
Often known to modern people as an old-timey disease linked to sin in religious texts, leprosy, or Hansen’s disease, is a chronic infectious disease caused by the bacteria M. leprae. Roughly 95% of people have natural immunity to the bacteria, according to the National Hansen’s Disease Program, which offers insight into why some once thought of it as an ailment that only affected the especially unpious.
The disease can be easily treated with standard antibiotics, and people are no longer contagious after just a few doses.
Leprosy, which can be traced back at least 4,000 years, can be highly visible and disfiguring, with the primary symptoms including changes to the skin and nervous system that can take upward of 20 years to develop after exposure. While there are several categories based on how the body responds, the CDC and Cleveland Clinic say common telltale signs include:
Patches of skin that are discolored or look different from the surrounding area. This can include dark lesions, paleness, redness, or skin that feels thick, stiff, swollen or numb
Swelling and/or red or purple nodules or lumps
Painless ulcers or sores on the bottom of the feet
Loss of eyebrows or eyelashes
Because leprosy damages the body’s nerves, muscles, skin, eyes and respiratory tract, more serious symptoms can develop, including:
Vision loss or other eye issues
Weakness or paralysis, which can become permanent
Nerve damage that causes decreased sensitivity and affects function in the hands and feet
Shortening of toes and fingers
Structural damage to the nose and hands
How leprosy spreads
If you’ve ever read or watched a period piece that dramatizes the plight of the leper, you’ve likely seen depictions of the latter, such as highly disfiguring symptoms that can cause permanent changes to the face. You may have also heard of leper colonies, where people we now know likely had a variety of skin conditions beyond just Hansen’s disease were sent to be isolated from the public.
Modern medicine tells us that the stigma and resulting isolation were unfounded, as Hansen’s disease is not easily spread from person to person. While it is believed to be airborne, meaning droplets produced when an infected person coughs or sneezes can spread it, you generally need to both lack immunity and spend an extended period in close quarters with untreated, infected people to catch it, according to the Cleveland Clinic, CDC, and National Hansen’s Disease Program. In other words, the risk to the general public is very low.
While scientists are looking into other potential avenues of harboring the disease-causing M. leprae, such as soil, there is a known risk factor: local armored critters.
Are armadillos the culprit?
Nine-banded armadillos are known to naturally carry M. leprae, the bacteria that causes leprosy.
Armadillos, specifically nine-banded armadillos, are known to carry M. leprae naturally, and a 2011 genome study found that they probably transmitted it to humans, as well. A subsequent study in 2015 further explored this animal-to-human spread and noted that “the geographic range and complexity of zoonotic leprosy is expanding.”
While they can’t yet be sure, scientists speculate that ample habitat conducive to more armadillos, possibly bolstered by climate change, could account for the increase in locally acquired cases in the American South, reported Florida Today, part of the USA TODAY Network.
In fact, contact with armadillos is considered one of those “traditional risk factors” mentioned in the 2023 report.
Case numbers correlate with the animal’s natural range, reported the Daytona Beach News-Journal, also part of the USA TODAY Network. It’s been suggested that coming into contact with soil contaminated by an armadillo also could affect humans, so gloves are recommended when gardening or digging. The general public is advised to avoid close contact with armadillos, including handling, skinning or eating.
Contributing: Anne Geggis and C. A. Bridges, USA TODAY NETWORK – Florida
This article originally appeared on USA TODAY: A 4,000-year-old disease is on the rise in this state thanks to armadillos
