Hansen’s disease is caused by infection with bacteria.
Evidence suggests that the bacteria that cause Hansen’s disease can spread from person to person. This might happen when someone with the disease coughs or sneezes. This can release droplets into the air. It might also happen if you are exposed to other nasal fluids (also known as secretions). Droplets and other secretions can contain the bacteria that cause Hansen’s disease.
If you breathe these in, you can become sick with the disease.