Florida leprosy cases may be here to stay. Do I need to worry?

Leprosy may sound like an affliction from a bygone era, but the disease — which historically also carries a strong social stigma — may be more present in the U.S. than you might expect, a new report indicates.

What's happening

A recently posted research letter in a journal published by the Centers for Disease Control and Prevention says there’s evidence that leprosy, also known as Hansen’s disease, has become “endemic,” or regularly occurring, in the Southeastern U.S., particularly in central Florida, where reported cases have more than doubled over the past decade.

The authors of the letter note that about 34% of new cases in the U.S. from 2015 to 2020 appeared to be locally acquired, and that several patients weren’t exposed to “traditional risk factors,” such as close, prolonged contact with someone infected with leprosy, interaction with armadillos (which can be carriers of the disease) or having traveled to an area where the disease is common.

Leprosy is an infection caused by the bacterium Mycobacterium leprae. It manifests as lesions and darker or lighter patches on the skin that may be reddish in color if inflamed, and lumps, particularly on the earlobes and face. If it's left untreated, nerve damage can occur that can cause tingling and eventual paralysis of hands and feet, loss of sight and eyebrows, and deformity of the nose, as nasal cartilage collapses.

Do I need to worry?

“The CDC has been clear that because the risk of leprosy in the United States remains very low, and because most people do not develop the disease following exposure, this should not be a cause of widespread alarm,” Dr. Jose Lucar, an infectious disease physician at the George Washington University School of Medicine, tells Yahoo Life. “[The CDC] also noted that a travel alert is not necessary to the parts of the country where local cases of leprosy are being reported, including central Florida.”

Here’s why experts say you shouldn’t stress.

• Leprosy doesn’t spread easily. Transmission still isn’t completely understood, although it’s believed to spread primarily through respiratory droplets. But while illnesses such as influenza or COVID-19 are easily acquired through droplets, the bacterium responsible for leprosy is so slow-growing that only extensive exposure will result in an infection. “Because it's so slow to reproduce, very prolonged close contact with untreated leprosy over several months is really needed to acquire the infection,” Lucar explains. “And we know that people don't get leprosy through casual contact, like hugging, shaking hands or sitting next to someone with the disease.”

• Most people have natural immunity to leprosy. The mycobacteria responsible for it are closely related to other bacteria, Dr. Nutan Gowda, a dermatologist at UMass Memorial Medical Center, told Yahoo News. “There are different mycobacteria in the soil, in the water, in the air that we’re exposed to on a daily basis, without even being aware of it. And that's how we develop immunity.”

• Some people are more susceptible to infection than others. Lucar says genes may also play a role. “We know through a number of studies that there are genetic factors related to the immune system, to its response to infections, that can make some people more susceptible to the infection than others," he notes. "So people who develop leprosy may have genes that make them more susceptible to infection.” But that accounts for a relatively small percentage of the population, with the CDC saying that over 95% of people worldwide have natural immunity. Each year, about 150 people in the U.S. are diagnosed with leprosy, and even health care workers rarely contract the disease.

• Treatments are extremely effective. Leprosy is curable, especially with early diagnosis and treatment, which involves a combination of antibiotics. But while the completion of antibiotic therapy takes anywhere from six months to two years, a person is no longer contagious within days of starting treatment.

What can I do about it?

While leprosy doesn’t present a major health threat, simple measures such as treating people who have the disease so they aren’t contagious and avoiding contact with armadillos (or wearing gloves and washing your hands if you do have contact with them) are important steps, Lucar says.

But more broadly, Nutan, who worked and trained at a leprosy clinic in north India, where the disease is endemic, points out that this news from Florida may also be a cautionary tale of the collective effort needed to fight global warming as more diseases emerge in unfamiliar places.

“We have infections that are appearing in areas that we never used to see before — not because of travel, but because the bacteria and viruses have new areas where they can thrive because of global warming,” Nutan says.

“Usually you don’t see leprosy in temperate climates," she adds. "We see it around the equator belt and where it is much warmer. But nowadays, we see bacterial illnesses that we used to see more in hotter parts of the country up in the Northeast, just because it's so much warmer now. So is that playing a factor? I don't think we have thought about that.”

The main takeaway

The researchers’ findings mean that clinicians or public health authorities in the U.S. may now consider Florida when conducting contact tracing for leprosy cases in the U.S. But it also illuminates gaps in leprosy research in the U.S. — especially regarding how the disease is spread.

“This essentially raises the need for further research into what other environmental sources may be playing a role in the transmission of infection,” Lucar says. “But this should not be a cause for public concern in general.”