Health officials are trying to track down people who may have been in contact with a woman with a rare and deadly form of extremely drug-resistant tuberculosis.
The woman has a form of the disease called XDR-TB, which doesn't respond at all to the four standard treatments for tuberculosis.
In April, the woman traveled from India to the United States, arriving at Chicago's O'Hare International Airport. She spent time in Missouri, Tennessee and Illinois. She was in the U.S. for about seven weeks before growing sick and being admitted to an isolation unit at a suburban Chicago hospital.
The woman is now being treated in an isolation unit at the National Institutes of Health hospital in Bethesda, Maryland, where she is in stable condition.
For someone with drug-resistant TB, "there are treatments that we use that are experimental," CBS News medical contributor Dr. David Agus, a professor of medicine at the University of Southern California Keck School of Medicine, told "CBS This Morning." "They take up to two years of these drugs, and so the treatments themselves are very toxic and require obviously significant costs and right now require for her to be contained in a facility at Building 10, which is the clinical center at NIH."
Although TB is not easily spread as a disease, it is dangerous, especially for people with weakened immune systems.
Health officials in Illinois are working with the Centers for Disease Control and Prevention to find people with whom the woman may have had prolonged direct contact, in close quarters, CDC spokesman Tom Skinner said.
Tuberculosis is not contagious by touch. Agus explained that TB bacteria gets into the air when someone who has the disease coughs or sneezes. The droplets of bacteria can then spread to other people who inhale them. "When someone coughed, that droplet can stay 2-3 hours in the air," Agus told CBS News. "And so tuberculosis really happens when people are in close quarters together, so that's why the people in her same row on a plane need to be identified and tested, and people who lived with her in the same house also need to be tested."
Tuberculosis usually affects the lungs and can lead to symptoms such as chest pain and coughing up blood.
TB has been declining in the United States. But globally, each year it sickens about 9 million people and is a cause of 1.5 million deaths.