Tuberculosis: 17 Questions and Answers
Confused About Tuberculosis Headlines? Get the Facts
WebMD News Archive
Atlanta lawyer Andrew Speaker has
been released from a Denver hospital where he was being treated for
Speaker's story has
raised questions about tuberculosis. Here are 17 questions and
What is tuberculosis?
Tuberculosis (TB) is an infectious
disease caused by a bacterium that spreads through the air, usually through
How common is tuberculosis?
According to the World Health
Organization, more than 8.8 million people worldwide are infected with
tuberculosis, and almost 1.6 million people per year die from
There are about 14,000 cases of
tuberculosis every year in the U.S., according to Carol Dukes Hamilton, MD, an
infectious disease specialist at Duke University Medical Center and the medical
director of North Carolina's tuberculosis control program.
"TB continues to be a really
major problem in the world. It's huge," Hamilton says.
"The most common thing people
say is, 'TB? I thought it was gone.' It's really not gone. And it can surge. It
can come back. We don't want to be alarmist, but we have to continue to pay
If millions of people have tuberculosis, why is Speaker's case different?
Unlike most tuberculosis patients,
Speaker has multidrug-resistant tuberculosis (MDR TB). He was earlier
thought to have extensively drug-resistant tuberculosis (XDR TB), which is even
Multidrug-resistant TB doesn't
respond to the first preferred tuberculosis drugs. XDR TB doesn't
respond to the first and second preferred drug treatments.
Speaker's case also garnered
instant attention when the CDC ordered him into isolation for medical treatment
and alerted the public about his travels so that passengers on his
transatlantic flights could get TB tests.
If tuberculosis is contagious, why don't Speaker's wife or friends have tuberculosis?
"It sounds like he's probably
somebody who was in a pretty early state of TB," says Hamilton, cautioning
that she isn't personally familiar with Speaker's case.
"He wasn't horribly sick
because he felt like going on his honeymoon and he was what's called 'smear
negative.' In those situations, often people aren't very infectious," says
What is "smear-negative" TB?
"What that means is that when
he coughed up a specimen to give to the doctors to test for TB, the laboratory
looked under the microscope [and] they didn't see any TB bacteria. It was only
when [the sample] was cultured that then they figured out, 'Oh, there really is
TB here' and then it took some weeks to figure out it was drug resistant,"
In contrast, smear-positive TB
patients "have so much TB in their lungs that when the laboratory looks
directly into the microscope, they can see the bacteria right there. Those
people tend to be a lot more infectious or contagious to others than someone
who really has disease but doesn't yet have enough built up that they're really
coughing out a whole lot at a time."
When TB bacteria keep growing,
eventually "you can see it under a microscope, and that's associated with
easily infecting other people," Hamilton says.