Leprosy is rare but far from gone. In 2024, 188 countries reported a combined 172,717 new cases to the World Health Organization. That number has held relatively steady for years, meaning tens of thousands of people still develop the disease annually despite it being curable. In the United States, between 124 and 216 cases are diagnosed each year.
Global Numbers in Context
The WHO declared leprosy “eliminated as a public health problem” at the global level in 2000, but that label is easy to misread. Elimination, in WHO terms, means prevalence dropped below 1 case per 10,000 people. Most individual countries hit that threshold by 2010. The disease didn’t vanish; it became uncommon enough that mass public health campaigns shifted to targeted efforts. Over 170,000 new diagnoses a year is still a significant burden concentrated in specific parts of the world.
India, Brazil, and Indonesia consistently report the vast majority of the world’s cases. India alone accounts for more than half of all new diagnoses in a typical year. Pockets of higher transmission also persist in parts of sub-Saharan Africa, Southeast Asia, and the Pacific Islands. Outside these regions, most cases involve people who were exposed before moving to lower-burden countries.
Leprosy in the United States
Between 2013 and 2022, the U.S. averaged roughly 150 to 175 cases per year. Most of these occurred in people who had lived in or traveled to countries where the disease is more common. However, a portion of U.S. cases have no clear overseas link. Endemic transmission, meaning the infection was acquired domestically, occurs in a handful of southern states including Florida, Louisiana, and Texas.
One unusual factor in the U.S. is armadillos. Nine-banded armadillos are the only known animal reservoir for the bacterium that causes leprosy. About one-third of U.S. patients deny any contact with an infected person and haven’t traveled to a high-burden region, and in those cases, armadillo exposure is the suspected source. This doesn’t mean handling an armadillo once will give you leprosy, but repeated contact raises the risk.
Why It Spreads So Slowly
Leprosy spreads through respiratory droplets, similar in principle to tuberculosis. A person with an active, untreated infection coughs or sneezes, and someone else breathes in the bacteria. The critical difference is that this needs to happen repeatedly over a long period of time. Brief or casual contact with someone who has leprosy carries very little risk, which is one reason the disease doesn’t spread widely in countries with decent healthcare access.
The bacterium behind leprosy grows extraordinarily slowly. The incubation period, the gap between exposure and the first symptoms, averages around five years but can stretch to 20 years. That long delay makes it hard to trace exactly when and where someone was infected, and it means some people carry the bacteria for years without knowing it.
What Symptoms Look Like
Leprosy primarily targets the skin, nerves, and the lining of the nose. Early signs are easy to overlook or mistake for other conditions. The most characteristic feature is patches of skin that are lighter or differently colored than surrounding skin. These patches often have reduced sensation, so you might not feel a pinch or a burn in that area.
Other signs include:
- Firm, rounded bumps under the skin
- Thick, stiff, or dry skin in patches
- Painless ulcers on the soles of the feet
- Swelling or lumps on the face or earlobes
- Loss of eyebrows or eyelashes
Nerve damage is the more serious consequence. Numbness in the hands and feet, muscle weakness, and visibly enlarged nerves near the elbows, knees, or neck are common as the disease progresses. Because affected areas lose feeling, injuries go unnoticed and can lead to secondary infections and permanent damage. This is the source of the disfigurement historically associated with leprosy, not the disease itself dissolving tissue, but repeated unnoticed injuries accumulating over time.
Treatment and Prevention
Leprosy is fully curable with a combination of antibiotics taken over six to twelve months, depending on the severity. Once treatment begins, a person quickly becomes non-infectious, typically within days. The challenge is reaching people before nerve damage becomes irreversible, which is why early detection matters so much in high-burden countries.
For people who live with or near someone diagnosed with leprosy, a preventive approach exists. A single dose of the antibiotic rifampicin, given to close contacts, reduces their risk of developing leprosy by about 57% over the following two years. The WHO recommends this strategy in programs that can properly screen contacts and manage follow-up, though it requires the diagnosed person’s consent to disclose their condition.
About 95% of people exposed to the bacterium never develop the disease at all. The human immune system clears the infection in the vast majority of cases, which is another reason leprosy remains uncommon even in regions where it circulates. Susceptibility appears to have a genetic component, meaning some people are simply more vulnerable than others regardless of how much exposure they have.