health

Tuberculosis (too-ber-ku-LO-sis) is a bacterial infection that spreads
through the air and usually affects the lungs. Worldwide, it kills more
people than any other infectious disease.
Tuberculosis is a potentially serious infection caused by Mycobacterium
tuberculosis bacteria. The bacteria are spread mainly through the air from
an infected person to others nearby. TB usually infects the lungs, but it
can also cause symptoms that affect the whole body.
Not everyone who is infected with tuberculosis bacteria (called primary
infection) gets sick or infects other people. About 10 million people in
the United States are infected with tuberculosis, but only 1 out of every
10 of these people develops active TB (called secondary infection). Of the
10 percent of infected people who ultimately develop active disease, about
one-third to one-half manifest illness in the first two months to two years
after they are initially infected; the remainder develop active TB later in life.
People with primary TB infection are protected from developing
active TB by their body’s immune system*, but they still carry the bacteria
in their bodies. As long as the infection is inactive, they cannot spread
TB. They can, however, develop active (secondary) TB years later if their
immune systems are weakened by other diseases such as HIV/AIDS or
diabetes, or by alcohol or drug abuse. Most people with active TB who
are treated can be cured. If left untreated, however, TB is fatal 40 to
60 percent of the time. Importantly, individuals discovered to have TB
infection can be given preventive therapy, which can reduce the lifetime
risk of developing active disease by at least 70 percent.

An Ancient Disease