SAN JOSE, Calif., Dec. 27 (UPI) -- Health officials are examining how a California woman infected with a possible drug-resistant strain of tuberculosis boarded an international flight.

The 30-year-old woman from Santa Clara County, Calif., infected with a possible drug-resistant strain of TB boarded an international flight to the United States in mid-December and didn't notify health officials, the San Jose (Calif.) Mercury News reported Thursday.

Authorities refused to identify the woman or reveal which country she was traveling from, the newspaper said.

Santa Clara County's public health officer, Dr. Marty Fenstersheib, asked how the woman boarded the international flight despite her TB diagnosis from overseas healthcare workers but noted she had no contact with the public after her arrival and therefore poses no threat to the general public.

TB spreads like the common cold and health officials said the risk of contamination is limited typically to close contact over extended periods but emphasize the confinements of commercial aircraft create a risk environment for transmission.

Officials with the Stanford Hospital and Clinic that is housing the patient said she remains in isolation and they are "taking all necessary precautions -- both to protect her and the public and our employees."

The U.S. Centers for Disease Control quarantined Andrew Speaker in May following the revelation he traveled to the United States from Czech Republic while carrying a virulent strain of tuberculosis.