Leprosy. Just the word conjures up Biblical images of disfigurement, isolation and stigma.

Though rare in the U.S., the number of cases has increased in the past 10 years in the Southeast, mostly in central Florida, according to recent research in the journal Emerging Infectious Diseases. 

And its authors say that may be a signal that the disease could be endemic to the Southeast.

Leprosy, also known as Hansen’s disease, is caused by bacteria called Mycobacterium leprae, which was discovered by Norwegian physician Dr. Gerhard Hansen in 1873, according to the U.S. Centers for Disease Control and Prevention.  

The disease is marked by lesions, growths, ulcers, numbness and muscle weakness and can lead to crippling of the hands and feet, paralysis, and blindness if it’s not treated, CDC reports. 

Once feared as highly contagious, it doesn’t spread easily through casual contact such as shaking hands, but rather through prolonged, close contact over many months with an infected person, according to the CDC, which notes that 95 percent of people are naturally immune to it. 

The agency reports that it can be cured with antibiotics.

The disease is not considered a public health problem in the United States, said Stefanie Weiland, former executive vice president of programs for the American Leprosy Missions, headquartered in Greenville, S.C.

While there are about 200,000 new cases every year worldwide, fewer than 200 cases are typically reported annually in the U.S., with most people contracting the disease in a country where it’s more common, such as Brazil and India, which have thousands of cases annually, she said. 

“The main thing is it is considered a rare disease,” Weiland said, “especially in the U.S.” 

The Florida Department of Health reported 11 cases in 2011 and 27 in 2020, but just 14 last year. Weiland said it’s unknown whether the pandemic played a role in the numbers. 

South Carolina has seen just five cases since 2013, according to the state Department of Health and Environmental Control, and all occurred among people from other countries who were thought to have been exposed overseas.

“This is a disease that is actually very difficult to transmit and spread,” said Dr. Jonathan Knoche, a medical consultant with DHEC’s Division of Immunization and Acute Disease Epidemiology.

“And it’s not a very common disease that we see,” he added. “It’s not like it was millennia ago, where if left untreated, it caused ulcers and paralysis and blindness. It’s very treatable.”

That treatment, a triple antibiotic combination, is very effective if the disease is caught early, Weiland said. But in countries where delayed diagnosis is a problem, people can still suffer irreversible nerve damage, she said.

The researchers wrote that there had been “an increased incidence of leprosy cases lacking traditional risk factors,” which, in addition to travel to endemic countries, include personal contact, occupational association, and exposure to animals that can carry the bacteria, such as armadillos. 

In the U.S., the armadillo has been a reservoir for the disease in Louisiana and Texas, and its range has been spreading eastward, Weiland said. And if the animal reservoir is expanding, it makes sense there would be more cases, she added.

Knoche agreed, saying there is clear evidence that as the habitat of certain animals expands, the diseases they have can expand into the human population more easily.

“Whether it’s carried by a mosquito or a tick or rodents or armadillos,” he said, “the opportunity for increased contact is definitely there.”

The CDC says that while there is a chance of getting the disease through contact with armadillos, the risk “is very low.”

Still, the researchers reported that the lack of traditional risk factors like armadillos, in addition to a decline in diagnoses in foreign-born people, is what contributes “to rising evidence that leprosy has become endemic in the southeastern United States.”

“That sounds alarming,” Weiland said. “But it’s not cause for alarm.”

That’s because the disease is still very rare in the U.S. and doesn’t occur in the kind of numbers associated with countries where it’s endemic, she said. 

Knoche said the researchers were trying to understand how people in Florida were infected and that their article, which highlighted a 54-year-old lifelong Florida resident who had the disease but none of the known risk factors, raises more questions than answers.

“A case report can raise questions for more rigorous scientific inquiry,” he said, “but is not a definitive word by any means.” 

And the CDC says that it’s frequently a challenge to identify how someone was infected because of the length of time it takes for symptoms to develop, which can be up to 20 years. 

Weiland said there are still a lot of unanswered questions about how leprosy is spread and that environmental transmission, including any potential unknown animal reservoirs, should be better researched.

The unsolved questions are barriers to ending the disease, Weiland said, adding that American Leprosy Missions is working to find approaches to end it, including investing in vaccine research, a new tool to speed diagnosis, and strengthening health systems worldwide to better respond with appropriate treatment and care.

“This article highlights that we should be paying attention,” she said, “… that we’re doing the right thing by researching the unknown questions and supporting the people who are deeply affected outside the U.S.”

The researchers also said their findings warranted further study.

“The absence of traditional risk factors in many recent cases of leprosy in Florida, coupled with the high proportion of residents, like our patient, who spend a great deal of time outdoors, supports the investigation into environmental reservoirs as a potential source of transmission,” they wrote.

Knoche noted that the CDC has not issued a travel advisory for Florida because of Hansen’s disease, and that he doesn’t expect to see a huge increase of the disease in South Carolina.

“I don’t have a concern over the normal activity of Hansen’s disease in the South Carolina population. It won’t sweep through society,” he said. “I wouldn’t change anything DHEC does as a result of this paper.”

Read the full article at: Case Report of Leprosy in Central Florida, USA, 2022 - Volume 29, Number 8—August 2023 - Emerging Infectious Diseases journal - CDC