Highlights
- The Emerging Pathogens Institute has responded to a rise in leprosy cases by convening experts to share the latest science on the disease and creating a team to address gaps in its research.
- Florida ranks among the states with the highest incidence of leprosy. The majority of Florida leprosy cases occur in Brevard County.
- Leprosy is rare, difficult to transmit and treatable. Medical professionals should know how to recognize its early symptoms, such as skin lesions and loss of sensation, to prevent delays in diagnosis.
- People can manage their risk for leprosy by avoiding contact with armadillos and wearing protective clothing and gloves while gardening.
Amid a growing number of leprosy cases in Florida and the U.S., the University of Florida’s Emerging Pathogens Institute has formed a multi-disciplinary research team to help resolve unanswered questions about the disease’s transmission and risk.
Leprosy, also known as Hansen’s disease, is on a gradual rise nationally, with about 150 to 200 new cases diagnosed each year. Florida ranks among the states with the highest incidence of the disease, with 263 confirmed cases from 2002 to 2022, according to the Florida Department of Health. Seventy of these cases were acquired locally.
Hansen’s disease is a potentially disfiguring illness that attacks the skin and peripheral nervous system. Symptoms can include skin abnormalities such as lesions and nodules, loss of feeling and thickened nerves. It is caused by the bacteria Mycobacterium leprae and, more rarely, M. lepromatosis. Despite being the oldest documented human disease, many of leprosy’s basic characteristics, including how it is transmitted, remain unclear.
EPI has convened a group of experts to research the illness using a One Health approach, a way of studying disease that explores the links between people, animals and the environment.
In Florida and other parts of the U.S., armadillos are a reservoir for the bacteria that cause Hansen’s disease and likely play a role in its spread. Florida patients diagnosed with leprosy are predominantly white men in their 60s, and many spent significant time outdoors for work or recreation.
EPI scientists will assess whether M. leprae is found in Florida’s environment and how armadillos may influence disease transmission. They will also study why Brevard County has a markedly higher incidence of the disease. FDOH data show that Brevard accounts for 40 of the state’s 74 leprosy cases from 2019-2022, far outstripping the county with the second-highest number – Polk County with four.
“We are seeing consistent transmission among certain regions of Florida,” said Norman Beatty, M.D., an assistant professor of medicine in UF’s Division of Infectious Diseases and Global Medicine and an EPI member. “We need to dive into the necessary research objectives, which are mainly centered on transmission and which populations are developing infection.”
Beatty and other members of the EPI leprosy research team presented the epidemiology of Hansen’s disease, clinical management approaches and prevention strategies at a recent EPI symposium.
Leprosy is treatable, but often misdiagnosed
Leprosy has been a highly stigmatized disease for millennia – and wrongly so, Beatty said. As recently as the last century, a diagnosis with the disease in the U.S. could result in lifelong banishment to a leprosarium.
Contrary to popular belief, leprosy is rare, difficult to transmit and treatable. An estimated 95-97% of people are naturally immune to the illness. People diagnosed with Hansen’s disease are prescribed a combination of antibiotics – most commonly moxifloxacin, minocycline and rifampin – for one to two years. After beginning antibiotics, patients are no longer infectious, and for many, symptoms are completely reversible.
“This is a treatable disease and curable,” Beatty said. “With early recognition, chronic conditions are less likely to occur.”
The growing number of Florida leprosy cases may represent an increasing recognition of the disease rather than an uptick in infections, said Nicole Iovine, M.D., a clinical professor at the UF College of Medicine, chief epidemiologist at UF Health and EPI member.
“There is no reason to panic,” Iovine said. “There are some very simple things people can do to reduce their risk. Avoid armadillos, and if you notice something on your skin, make sure you bring that to medical attention.”
Experts’ primary concern is ensuring that healthcare providers are equipped to diagnose Hansen’s disease, said Jessica Fairley, M.D., associate professor at Emory University’s Rollins School of Public Health and director of the Emory Hansen’s Disease Program.
A person can be infected with the bacteria that causes leprosy for years or decades before showing symptoms, a byproduct of the pathogen’s unusually slow reproduction. Even after symptoms appear, the disease is often misdiagnosed, increasing the chances a patient may experience irreversible nerve damage. In Florida, the median time from the onset of symptoms to diagnosis is 8.5 months, according to FDOH.
Iovine cited the case of a 78-year-old Floridian who visited four dermatologists for a persistent rash on his trunk before receiving a diagnosis of Hansen’s disease from UF Dermatology.
“The main thing we need to work on is provider awareness,” said Fairley, who is collaborating with the EPI leprosy research team.
How to recognize the early signs of a leprosy infection
Most people who develop early symptoms of leprosy will recover on their own, and some may live with the illness without ever knowing they have it, said Kartik Cherabuddi, M.D., professor at the UF College of Medicine and an EPI member.
Early diagnosis and treatment, however, are key to reducing the risk of possible disability or disfigurement, he said.
Cherabuddi advises medical professionals to look for skin lesions that are pale or reddish and to test lesions for sensation by tapping the skin with a pen or tongue depressor. Loss of feeling is an early symptom of Hansen’s disease.
“What’s really unique about leprosy compared to most other skin diseases is decreased or loss of sensation in that skin lesion area,” he said. “This is what we want every practitioner out there to know. Think of it when you are evaluating any skin lesion.”
Physicians should also examine peripheral nerves for thickening, tenderness, consistency and function. A skin biopsy is the most effective way to diagnose Hansen’s disease in the laboratory, and referral to a specialized center may be helpful, Cherabuddi said.
The factors that can make an individual more susceptible to leprosy remain unknown, but Cherabuddi suspects that genetics, nutrition and reduced immune function could play a role.
“Epidemiological research is urgently needed to define the transmission mechanisms and risk factors for developing Hansen’s disease in the United States before it becomes a much bigger problem,” he said.
Reactions complicate treatment of Hansen’s disease
While Hansen’s disease is more common in Brazil, Central Africa, India and Southeast Asia, Fairley said her clinic is seeing higher numbers of U.S.-born patients over time, indicating that the disease is being transmitted Stateside.
Leprosy’s long incubation period makes it difficult to trace a patient’s source of infection, and M. leprae and M. lepromatosis cannot be grown in the laboratory, complicating the study of the pathogens.
Researchers are also unsure of the exact mechanism of leprosy’s transmission. It is commonly thought transmission can occur after prolonged contact with another infected person or exposure to an infected armadillo or contaminated soil, but scientists have been unable to pinpoint the pathogen’s exact route.
Whether the bacteria are passed through the air or touch is also unclear, Fairley said. Her clinic has not seen any cases of leprosy that were transmitted between people living in the same household, which occurs more frequently outside the U.S.
While leprosy is not considered a lethal disease, Fairley said about 75% of her patients experience immunologic reactions to bacterial antigens that persist in the skin. These reactions can be sudden, acute and unpredictable, ranging from a rapid outbreak of head-to-toe nodules to renal failure. Managing these flare-ups can result in patients staying on antibiotics far longer than the typical treatment period. One patient has had episodes for more than 10 years, she said.
“This is not a simple disease to treat,” Fairley said. “[These reactions] are what keep me up at night.”
How to manage leprosy risk in Florida
The nine-banded armadillo, Dasypus novemcinctus, a common species in Florida, is the only known reservoir of M. leprae in the Americas. Armadillos also experience leprosy as humans do, developing skin abnormalities over time, said Juan Campos Krauer, D.V.M., Ph.D. Campos Krauer is an assistant professor in the UF College of Veterinary Medicine and a member of EPI’s leprosy research team.
Infected armadillos can shed M. leprae in their feces, potentially contaminating soil with the bacteria, which can survive in the environment for 46 days. Research shows 5 to 16% of Florida’s armadillos carry the bacteria. How they become infected and pass on the pathogen, however, remain key research questions, said Campos Krauer, who is also a veterinarian in the UF/IFAS Department of Wildlife Ecology and Conservation.
“Information on what happens to armadillos is really important to mitigating this disease,” he said.
Campos Krauer said he is particularly concerned that road-killed armadillos may be a source of infection for other armadillos, a potential route of disease transmission he plans to study.
While the risk of contracting leprosy from armadillos is small, Campos Kraur advises maintaining a respectful distance from the animals. Avoid handling, hunting or eating them. If you hit an armadillo with your car, wear gloves to wash away organic material. Hire professionals to trap and remove nuisance armadillos from your property, rather than interacting with them yourself.
To avoid contact with potentially contaminated soil, wear gloves and protective clothing when gardening, and wash homegrown vegetables before eating them.
Campos Krauer emphasized that people do not need to be alarmed when they see armadillos in the wild or in yards and gardens. Armadillos do not bite and will flee or hide if startled.
“Armadillos do not pose an active threat to people,” he said. “It’s just something extra to be aware of.”
Written by: Natalie Van Hoose