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Lung Disease & Respiratory Health Center

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Tuberculosis: 17 Questions and Answers

Confused About Tuberculosis Headlines? Get the Facts

What is "smear-negative" TB? continued...

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.

Speaker has said he felt fine and had been exercising with no obvious symptoms. How is that possible? Is that because he was in the early stages?

"That's definitely how that's possible," says Hamilton.

She recalls the case of a surgeon who operated on a patient who was later found to have TB and who was also exposed to TB while working in Africa.

"He had TB," Hamilton says. "In talking with him, he said, 'Well, when I do my five-mile runs, I might have noticed I was slightly more out of breath than usual.' In other words, [he was] healthy, working, running, totally fine," Hamilton says.

"I feel quite certain that as time went on, he would have become ill. He just wasn't quite there yet," she says. "It goes to show that this disease can kind of sneak up on people."

Do most TB patients have symptoms, and what are tuberculosis symptoms?

"That's what we think, that most people eventually have some kind of symptom," says Hamilton.

When people get sick with tuberculosis, their symptoms may include fever, night sweats, cough, appetite loss, weight loss, bloody phlegm, and loss of energy.

Can anyone catch TB?

"Yes, if they are in close association with someone who has tuberculosis," says Hamilton.

"That means not just walking past them in Hartsfield Airport in Atlanta," she adds.

"Usually it's sharing an office with them, living in the same household with them, being in a homeless shelter with them and sleeping in a bed next to them -- [spending] time with that person."

"Tuberculosis is around," Hamilton says. "Does that mean people should be nervous about going to the mall? No. It's not horribly common. Now, if people travel to countries where there's still a lot of TB, then your risk is increased."

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