A 4,000-Year-Old Disease Returning in Florida

A disease with roots stretching back 4,000 years is making an unexpected resurgence in the U.S.

Leprosy, or Hansen’s disease, might seem like a relic of the past, yet Florida has reported 17 cases this year as of July 18, according to health data from the state. Out of the 174 cases reported nationwide in 2025, Florida accounted for 36, with 27 of those considered local infections rather than imported.

In the U.S., Hansen’s disease impacts about 225 individuals each year, while globally the number reaches around 250,000, according to the CDC. Although most infections originate from abroad, some Southern states have noted cases that were possibly “likely contracted from armadillos,” according to CDC insights.

Over the last decade, Florida has seen approximately 223 leprosy cases, particularly concentrated in Brevard County. Central Florida stands out as a notable hotspot, comprising about 81% of the state’s cases and nearly a fifth of those reported nationwide, as noted in a 2023 CDC journal article.

While patterns indicating a rise in cases are evident, the exact reasons remain unclear. The same report from 2023 observed a growth in infections among residents who lacked the usual risk factors, suggesting the disease may be becoming endemic in some U.S. regions, with one case involving a landscaper igniting discussions about environmental exposure.

Although still considered rare, the increase in cases has sparked concern. Following a peak in 1983, U.S. leprosy cases generally decreased but have seen a resurgence since the late 1990s.

Understanding Leprosy

Frequently associated with historical depictions, leprosy is known as a chronic infectious disease caused by the bacteria M. leprae. Interestingly, around 95% of the population possesses some level of immunity to it, as noted by the National Hansen’s Disease Program. This helps explain why it was once misconceived as a disease only affecting the sinful.

Standard antibiotics can effectively treat leprosy, rendering individuals non-contagious after just a few doses. The disease, traced back for millennia, can lead to significant and visible disfigurements, often manifesting with skin and nervous system alterations, sometimes taking over 20 years to show signs after exposure. While different categories exist based on body response, common indicators include:

• Patches of skin that appear discolored or different—these may present as dark lesions, pale areas, or skin that feels swollen or numb.
• Red or purple lumps or nodules.
• Painless sores on the feet.
• Loss of eyebrows or eyelashes.

More severe symptoms can arise due to nerve damage, affecting various body systems and potentially leading to:

• Vision issues.
• Permanent weakness or paralysis.
• Nerve damage with reduced sensitivity, impacting hands and feet.
• Shortened fingers and toes.
• Structural damage to the nose and extremities.

Transmission of Leprosy

In historical depictions, lepers often faced isolation due to their disfiguring symptoms. Modern understanding, however, reveals that Hansen’s disease isn’t easily transmittable. While it’s believed to be airborne, catching it typically requires close, extended contact with untreated individuals lacking immunity, according to the Cleveland Clinic and other health resources. The general public is at very low risk.

Scientists are exploring additional ways the bacteria might survive outside of human hosts, with armadillos emerging as a known factor.

Are Armadillos Responsible?

Nine-banded armadillos are known carriers of M. leprae, and a 2011 genome study suggested they likely transmitted the bacteria to humans. Further research in 2015 indicated that the geographical spread of zoonotic leprosy is increasing.

While uncertain, scientists hypothesize that favorable habitats for armadillos—potentially worsened by climate change—could explain the rise in local infections in the Southern U.S., as highlighted by reports. Contact with these creatures is recognized as a “traditional risk factor” in the ongoing health discussions.

Reported connections exist between leprosy cases and the habitats of these animals. It’s suggested that soil contamination by armadillos could also pose risks, so gardening with gloves is advisable. People are generally warned against close encounters with armadillos, such as handling or consuming them.