Leprosy has made a surprising (and wholly unwelcome) comeback in Florida, as per a new report published by the US Centers for Disease Control and Prevention (CDC). Worse still, the new report suggests that the infectious disease could be endemic in the Sunshine State, meaning it's there to stay. 

The case report cites that 159 leprosy cases were reported in the US in 2020, with Florida being the most reported state. Central Florida accounted for 81 percent of the state’s cases and almost one-fifth of those nationally reported cases.

Leprosy has been feared since biblical times. Also known as Hansen's disease, it’s a long-term infection caused by the bacteria Mycobacterium leprae or Mycobacterium lepromatosis, which can lead to damage to the nerves, respiratory tract, skin, and eyes. Typical symptoms include discolored patches of skin, unusual growths on the skin, ulcers on the soles of feet, painless swelling of the face, numbness, and potential paralysis.

Nerve damage is an especially troublesome element of the disease as it results in a lack of ability to feel pain, allowing damage and infection to body parts to go unnoticed. Sometimes, the damaged limbs have to be amputated, although this has become relatively rare in modern times thanks to early detection and treatment.

The disease was historically uncommon in the US. If cases did emerge, they were usually introduced from another part of the world where the disease is more endemic. However, the report states that now one-third of cases appear to have been locally acquired. Most cases also emerge in people born in the US, which is significant as the slow-growing nature of the bacteria can mean it's quietly picked up in early life but only emerges later on.

“This information suggests that leprosy has become an endemic disease process in Florida, warranting further research into other methods of autochthonous transmission,” the report reads.

The report authors say they are puzzled by the source of the infections. More broadly speaking, scientists are relatively uncertain how about leprosy spreads. It’s believed that prolonged close contact with an untreated leprosy case, perhaps over the course of many months, is needed to catch the disease.

One suspect behind the recent surge of cases in Florida is an animal. The case report notes that many cases have been seen among people who spend a lot of time outside, suggesting they are coming into contact with the pathogen through exposure to the natural environment. 

Oddly enough, armadillos are known to carry the bacteria in parts of southern Florida, further supporting this idea. That said, leprosy is also on the rise in other parts of the US where armadillos don’t naturally live. 

The good news is that around 95 percent of people have a natural immunity to leprosy. It is also treatable if caught in time. Patients are typically given a combination of antibiotics which have to be taken regularly for a couple of years. 

Nevertheless, that won’t be much comfort to the minority of people who can catch this nasty disease. 

The new case study is reported in the CDC’s journal Emerging Infectious Diseases.