Leprosy Today: What Infection Preventionists Still Need to Know

Leprosy is often misunderstood as a disease of the distant past, yet it remains a global public health issue with ongoing implications for infection prevention. In this interview, Matthew Pullen, MD, an infectious disease physician and assistant professor of infectious diseases and international medicine at the University of Minnesota, breaks down the current epidemiology, including how dramatically case rates have declined and where infections still occur today.

Pullen, who is also a member of Infection Control Today^®’s (ICT^®’s) editorial advisory board, addresses persistent misconceptions about transmission, stigma, and the practical infection prevention measures health care professionals should understand.

ICT: Leprosy is often viewed as a disease of the past. From an infection prevention perspective, how prevalent is leprosy globally, and what misconceptions still exist among health care professionals today?

Matthew Pullen, MD: You're right that a lot of progress has been made in looking at [leprosy] in a wider scope. Over the last 40 years, the incidence has decreased by several orders of magnitude. Much of that is through enhanced monitoring, enhanced diagnosis, and just appropriate treatment.

Those who have made a pretty big effort have declared it one of the diseases they want to try to eradicate. It's not quite there, but it's making a lot of progress. If you look as far back as 1985, the prevalence for every 100,000 people globally was 21.1 cases. So not huge, but definitely prevalent.

As of 2022, that was down to 0.21 cases per 100,000, a 2 orders-of-magnitude decrease. So you still definitely have cases. There are about 180,000 cases per year globally, but that's down from nearly 5 million in 1985, so very, very good progress in the US. It's even smaller. In 2024, only 205 new cases were documented in the US.

On average, over the last decade, we see about 120 to 220 cases a year in the US. Most of those are from people coming from abroad, from immigrant populations, so likely they were exposed overseas, or if they are a native-born US citizen, it's typically cases where they were exposed overseas.

Routine travel is not recognized as a risk factor, so it’s not something you have to be super mindful of. Some domestic cases in the US are tied to exposure to nine-banded armadillos. It's the only animal reservoir we know for sure can carry the disease. So don't handle nine-banded armadillos. Don't eat nine-banded armadillos. It's really more of a concern in the southwest.

As far as misconceptions about leprosy, the biggest one ties into the point about stigma that you made. Historically, people with leprosy were put in leper colonies, or they were isolated from society. Leprosy is not actually highly contagious. There's no real documented human-to-human transmission, especially when someone starts on treatment. Transmission is not totally understood, so it's understandable.

There's still some concern. But even in the hospital, we would recommend standard precautions, especially once you get someone started on treatment. We think that it's mostly spread through respiratory droplets of untreated individuals. But again, that's poorly understood.

ICT: Is there a vaccine?

MP: Not that I'm aware of, as far as anything that's widely used. I'm not sure if there's one in clinical trials. I don't know that there is. Typically, we focus on treatment with 2 or 3 antibiotics, depending on the form of disease. So, most of the effort focuses on monitoring, diagnosis, and treatment.