Leprosy is rare but on the rise in Florida — here's what to know

The word "leprosy" conjures images of biblical plagues, but the disease is still with us today. Caused by infectious bacteria, some 200,000 new cases are reported each year, according to the World Health Organization. In the United States, leprosy has been entrenched for more than a century in parts of the South where people came into contact with armadillos, the principle proven linkage from animal to humans. However, the more recent outbreaks in the Southeast, especially Florida, have not been associated with animal exposure.

The Conversation talked with Robert A. Schwartz, professor and head of dermatology at Rutgers New Jersey Medical School, to explain what researchers know about the disease.

What is leprosy and why is it resurfacing in the U.S.?

Leprosy is caused by two different but similar bacteria — Mycobacterium leprae and Mycobacterium lepromatosis — the latter having just been identified in 2008. Leprosy, also known as Hansen's disease, is avoidable. Transmission among the most vulnerable in society, including migrant and impoverished populations, remains a pressing issue.

This age-old neglected tropical disease, which is still present in more than 120 countries, is now a growing challenge in parts of North America.

Leprosy is beginning to occur regularly within parts of the southeastern United States. Most recently, Florida has seen a heightened incidence of leprosy, accounting for many of the newly diagnosed cases in the U.S.

The surge in new cases in central Florida highlights the urgent need for Health care providers to report them immediately. Contact tracing is critical to identifying sources and reducing transmission.

Traditional risk factors include zoonotic exposure and having recently lived in leprosy-endemic countries. Brazil, India and Indonesia have each noted more than 10,000 new cases since 2019, according to the World Health Organization data, and more than a dozen countries have reported between 1,000 to 10,000 new cases over the same time period.