The frenzy over tuberculosis spawned by a single "extensively drug-resistant" case is capturing headlines. But most people exposed to the airborne bacteria will never develop active disease.

The Atlanta attorney's case has health officials concerned because his TB falls into a class of infections that resists two first-line TB drugs and some second-line drugs — one of only 49 other extensively drug-resistant cases reported in the United States between 1993 and 2006. There's also a class called multidrug-resistant TB, which is easier to treat than cases like this one but more difficult than typical TB.

Although it's harder to kill, it's no easier to spread than any other tubercolosis, according to Carrie Taylor, an infection control practice nurse at LDS Hospital. "You have to breathe in air that's coughed."

Doctors treat an average of 38 active TB cases each year in Utah, according to the Utah Department of Health. The disease usually settles in the lungs, although it can affect the kidneys, spine, brain and other organs.

The disease is caused by Mycobacterium tuberculosis, which spreads person-to-person but only through close contact. Taylor and her colleague Vickie Anderson, also an infection-control practice nurse at LDS Hospital, describe it as passing from one person's lungs directly into another's. It's not like a cold that is easily spread and fairly hardy. In fact, sunlight kills it.

Unless the individual has a drug-resistant TB strain — "not common in Utah," said Taylor — it's very treatable, although it takes a long time and several medications. Left untreated, it can kill. At least initially, patients are isolated to avoid spread of the disease.

Both chicken pox and measles are more contagious, said infectious disease specialist Dr. John Kriesel of University Hospital. As an example, when a Provo High School student was recently diagnosed with tuberculosis and health officials asked 250 of the student's school contacts to be tested for it, Kriesel predicted "not one of them will test positive for TB."

People in casual contact are extremely unlikely to get the disease. Just being exposed doesn't mean you could pass it on, Taylor said. Without symptoms, you can't spread it, even if you have a positive skin test. People who live with a patient are at higher risk, but most won't get it, either.

As for folks who sit by someone on a plane, spread is unlikely unless the individual is coughing directly into the faces of seatmates.

TB symptoms include coughing that lasts three weeks or more, pain in the chest, blood in sputum, weight loss, night sweats, fever and fatigue, in various combinations.

In some people who breathe in the mycobacterium, it is "inactive but alive" in the body, Anderson said. That person has no symptoms, doesn't feel sick and can't spread it. At some later point, though, it can become active, so Kriesel said those with a positive skin test for TB are treated.