Tuberculosis (TB) is an infectious disease caused by a germ, or bacterium, called Mycobacterium tuberculosis. This germ often affects the lungs, however, it may involve any organ and may infect anyone at any age.
It is resistant to most antibiotics and, thus, difficult to treat.
Left untreated,TB can kill approximately one half of patients within five years and produce significant morbidity (illness) in others. Inadequate therapy for TB can lead to drug-resistant strains of M. tuberculosis that are even more difficult to treat.
TB Case Rate in the U.S.
In the United States, the number of TB cases steadily decreased until 1986. Then an increase was noted. Since 1992, TB has been declining. In 2008, the case rate was 4.2 per 100,000 in the population. This is about 12,898 new cases of active disease each year.
Although there has been a decrease in the number of cases that are reported in U.S.-born individuals, the number of cases in people born outside of the U.S. has failed to decline
People at Risk
Anyone can become infected with M. tuberculosis simply by breathing in the germs, but in the United States today, TB disproportionately involves immigrants and minorities. Those who originated in Asia, the Indian sub-continent, Africa, Latin America or Russia/the former Soviet Republics have a much greater likelihood of harboring TB infection than U.S. citizens. The risk for active TB is highest in the first few years after immigration but persists for a lifetime.
Within the indigenous U.S. population, the risk is greater among Hispanic, African-American or Asian-American individuals. Other factors, which increase the risk for latent TB infection are time in prison, healthcare employment or extended travel in high risk areas. HIV infections or AIDS dramatically increases the risk of TB reactivation.
Most TB is seen in adult populations, the risk is increasing with age. However, children in households with an active-TB case may be at high risk.
This information has been approved by Gwen Huitt, MD and
Michael Iseman, MD
(September 2009).
