Leprosy does indeed still exist, less commonly in the United States than in other parts of the world, but around 100 to 200 people are infected in the U.S. each year. Most of these patients live in the southern U.S. (Texas and Louisiana). Interestingly, only two animals carry the bacteria that causes leprosy: humans and armadillos. Recently (April 2011), the New England Journal of Medicine--one of the most preeminent scientific journals worldwide--published a study showing that the leprosy bacterium carried by wild armadillos was identical to the leprosy bacterium found in most humans with leprosy infections in the U.S. Therefore, I would recommend avoiding close contact with armadillos, including hunting, skinning, and handling or eating armadillo flesh.
The exact mechanism of leprosy transmission is still unknown. It may spread from human to human by close contact or by airborne droplets. Typical symptoms are open sores that are numb in the center. If you believe you or someone you know has leprosy, you should contact an Infectious Diseases specialist. Leprosy can be treated with antibiotics once it has been diagnosed.
In general, people who volunteer in homeless shelters should be sure to get screened for tuberculosis (TB), which can be done by your primary care doctor
or by an Infectious Diseases specialist.