Hansen Disease (Leprosy) in the United States

Jennifer Middleton, MD, MPH
Posted on August 14, 2023

A U.S. Centers for Disease Control and Prevention (CDC) case report published earlier this month finds that documented cases of Hansen disease (leprosy) have more than doubled in southeastern states since 2013 and may now be endemic in central Florida. Although overall rare in the United States, with typically no more than 200 cases a year, Hansen disease is curable, and family physicians should be able to recognize its various presentations.

Although Hansen disease has been reported since antiquity, it’s still not entirely understood how it is transmitted. Infected people may not show signs or symptoms for up to 20 years, making contact tracing impossible. Caused by the slow-growing bacteria Mycobacterium leprae, Hansen disease causes a wide range of skin and peripheral nerve symptoms, including numb hypopigmented (or erythematous) skin patches and painless palpable nodules caused by swelling of peripheral nerves. Advanced Hansen disease can afflict the bones, causing resorption of toes (“hammer toes”) and fingers (“claw hands”) and/or a saddle nose deformity. These disfiguring complications can lead to social isolation and, in many parts of the world, beliefs that the disease is caused by personal failing such as “bad blood, curse, heredity and bad deeds.”  When identified and treated early, the life-altering complications can be entirely prevented. Physicians concerned about a possible diagnosis of leprosy should contact the National Hansen’s Disease (Leprosy) Program run by the U.S. Health Resources and Services Administration (HRSA).

Hansen disease is difficult to contract; 95% of the population is naturally immune to infection with Mycobacterium leprae. Scientists estimate that a susceptible person would need to spend months in close contact with an infected individual—or armadillo—to contract the disease. The authors of this new case report have stressed that the U.S. public does not need to be alarmed about this small uptick in cases:

'It’s a drop in the bucket, especially when you view it through a global lens,' said Dr. Charles Dunn, a dermatologist and an author of the study... 'Our paper simply highlights that there appears to be this really intriguingly strong geographic predilection for this illness that’s very uncommon,' he added... The Centers for Disease Control and Prevention 'does not believe there is a great concern to the American public,' a spokeswoman said in an email. The number of cases 'is very small.'

U.S. family physicians, though, should still keep leprosy on our radar. All of us are likely to care for people who have travelled to various areas of the world, which now may include central Florida, where Hansen disease is endemic. A 2017 AFP Photo Quiz reviewed the case of a young man who had arrived in the United States six months prior with painless nodules who was diagnosed with Hansen disease; the article includes a discussion of other diagnoses with similar presentations (annular psoriasis, cutaneous leishmaniasis, and keloids). Multiple organizations can provide additional information about Hansen disease, including the CDC, HRSA’s National Hansen’s Disease (Leprosy) Program, and the World Health Organization. You may also want to check out the AFP By Topic on Skin Conditions.