Leprosy may sound like a disease from a bygone era, but the disease, which has historically carried a strong social stigma, may be more common in the U.S. than you might expect, a new report finds.
What is going on
A recently published research letter in a journal from the Centers for Disease Control and Prevention says there is evidence that leprosy, also known as Hansen’s disease, has become “endemic,” or frequently occurring, in the southeastern U.S., particularly in central Florida, where the number of reported cases has more than doubled in 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 had not been 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 travel to an area where the disease is common.
Leprosy is an infection caused by the bacteria Mycobacterium leprae. It manifests as lesions and darker or lighter patches on the skin that may be reddish in color when inflamed, and bumps, especially on the earlobes and face. If left untreated, nerve damage can occur causing tingling and eventually paralysis of the hands and feet, loss of vision and eyebrows, and deformity of the nose as the nasal cartilage collapses.
Should I be concerned?
“The CDC has made it clear that because the risk of leprosy in the United States remains very low, and because most people do not develop the disease after exposure, this should not be a cause for widespread concern,” Dr. Jose Lucar, an infectious disease physician at George Washington University School of Medicine, tells Yahoo Life.[The CDC] also noted that a travel warning is not necessary for parts of the country where local cases of leprosy are reported, including central Florida.”
That’s why experts say you shouldn’t worry.
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Leprosy does not spread easily. Transmission is still not entirely clear, although it is thought to spread primarily through respiratory droplets. But while diseases like influenza or COVID-19 are easily transmitted through droplets, the bacteria responsible for leprosy grow so slowly that only extensive exposure will lead to infection. “Because it reproduces so slowly, very prolonged close contact with untreated leprosy over several months is really necessary to get 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 who has the disease.”
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Most people are naturally immune to leprosy. The mycobacteria responsible for this 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 every day, without even realizing it. And that’s how we develop immunity.”
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Some people are more susceptible to infections than others. Lucar says genes may also play a role. “We know from a number of studies that there are genetic factors related to the immune system, to the response to infection, that may 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’s a relatively small percentage of the population, with the CDC saying that more than 95% of people worldwide have natural immunity. About 150 people in the U.S. are diagnosed with leprosy each year, and even health care workers rarely get the disease.
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The treatments are extremely effective. Leprosy is curable, especially with early diagnosis and treatment, which involves a combination of antibiotics. But although it takes six months to two years to complete antibiotic therapy, a person is no longer contagious within days of starting treatment.
What can I do about it?
While leprosy does not pose a major health risk, simple measures such as treating people who have the disease so they are not contagious and avoiding contact with armadillos (or wearing gloves and washing your hands if you do come into contact with them) are important steps, Lucar said.
But more broadly, Nutan, who worked and trained at a leprosy clinic in northern India, where the disease is endemic, points out that this news from Florida could also be a warning about the collective effort needed to combat global warming as more diseases emerge in unfamiliar places.
“We have infections popping up in areas we never saw before — not because of travel, but because the bacteria and viruses have found new areas where they can thrive because of global warming,” Nutan says.
“You don’t usually see leprosy in temperate climates,” she adds. “We see it around the equatorial belt and where it’s much warmer. But now we’re seeing bacterial diseases that we used to see more in warmer parts of the country in the northeast, just because it’s so much warmer now. Is that a factor? I don’t think we’ve thought about that.”
The main conclusion
The researchers’ findings mean that clinicians or public health authorities in the U.S. may now consider Florida when conducting contact investigations for leprosy cases in the U.S. But it also highlights gaps in leprosy research in the U.S., particularly in how the disease spreads.
“This essentially raises the need for further research into what other environmental sources play a role in the transmission of infection,” Lucar says. “But this should not be a cause for public concern in general.”
