A California woman with a multi-drug resistant form of tuberculosis flew home from India earlier in December on a commercial passenger plane and is in isolation now. Authorities say they don't know how the woman was able to board an international flight because she had been diagnosed in India with the dangerous form of TB that she had been told was highly contagious when physicians began treatment there.

The woman's name has not been released. But Santa Clara County Health Department officials said she knew she was sick when she took a plane home on Dec. 13. Authorities say that was lucky because the woman was too sick to go out Christmas shopping where she would have exposed even more people to the disease.

Despite being sick, however, the woman didn't seek treatment here until Dec. 19 when she went to the Stanford emergency room seeking help.

The County Health Department has already contacted everyone who was in the emergency room then. The Centers for Disease Control is trying to contact all passengers who might have been exposed to the TB.

On Thursday the CDC gave health officials in 16 states the names of passengers who had sat within two rows of the woman on her flight home. That flight was American Airlines Flight 293 from New Delhi to Chicago's O'Hare airport on Dec. 13. Those people need to be tested for TB.

Health authorities are making sure the patient won't have a chance to infect anyone else.

"The patient is in isolation, and we're taking all necessary precautions -- both to protect her and the public and our employees," Shelley Hebert, executive director for public affairs for Stanford Hospital & Clinics, told the San Jose Mercury News.