Tuberculosis, once the leading cause of death in the U.S., has become less deadly, but the disease remains a threat to millions of Americans.
An estimated 10 million to 15 million Americans have been infected with the airborne TB bacteria, and 10% will develop active TB sometime in their lives, according to the U.S. Centers for Disease Control and Prevention.
In 1997, 19,851 active TB cases were reported in the U.S., down from 21,337 in 1996.
From a high of 195 per 100,000 a century ago, the TB death rate dropped to 85 per 100,000 in 1925 and 22 per 100,000 in 1950. By 1960 the rate had dropped to 6 per 100,000.
About 2 billion people, one-third of the world's population, are infected with TB.
There are 8 million new cases each year and about 3 million TB-related deaths worldwide.