How Hansen's Disease Spreads

Key points

  • Hansen's disease is caused by a slow-growing bacteria.
  • Hansen's disease is difficult to contract and easy to treat.
  • It is possible, but unlikely, to get Hansen's disease from armadillos in the southern United States.


Hansen's disease is caused by slow-growing bacteria called Mycobacterium leprae and Mycobacterium lepromatosis.

How it spreads

Hansen's disease likely spreads when a person sick with the disease coughs or sneezes, and a healthy person breathes in the droplets containing the bacteria. Hansen's disease does not spread easily between people.

Most people cannot get Hansen's disease. Around 95 percent of people cannot be infected because their immune system can fight off the bacteria that causes Hansen's disease.

In addition, you must have prolonged, close contact with someone with untreated Hansen's disease over many months to catch the disease. Hansen's disease is not spread through sex, and it is not passed to the fetus during pregnancy.

In the southern United States, some armadillos are naturally infected with the bacteria that cause Hansen's disease, and it may be possible that the animals can spread it to people. However, the risk is very low and most people who come into contact with armadillos are unlikely to get Hansen's disease.

You cannot get Hansen's disease through:‎

casual contact, like hugging or shaking hands, sitting next to someone on the bus, or sharing a meal.

Myths and misconceptions

Despite the disease being hard to catch and completely curable, a lot of stigma and prejudice against people with Hansen's disease remains. Learn more about myths about Hansen's disease.