A federal health official said yesterday it could take months to determine if anyone aboard two May 11 flights -- the first originating in Baltimore -- was infected by a female passenger who had a terminal case of tuberculosis.
Dr. Kenneth Castro, director of tuberculosis elimination for the // Centers for Disease Control and Prevention, said the Atlanta-based agency is contacting about 450 people who flew on United Airlines flights from Baltimore to Chicago and from Chicago to Honolulu.
Early this week, CDC investigators began notifying passengers that they may have been exposed to tuberculosis and should get tested for the disease. Reaching all the passengers -- by telephone and by mail -- could take another week or two, he said.
Determining if anyone was infected will take much longer, he said. People are being advised to contact private doctors or public health clinics and take skin tests that indicate whether they were infected. In some cases, a person who tests negative will have to take another skin test weeks later to confirm it.
"We anticipate the full investigation won't be completed for the next several months," Dr. Castro said.
Tuberculosis is a bacterial disease spread in airborne droplets by coughing, sneezing and, in some cases, talking. The disease usually attacks the lungs, and can cause chest pain, shortness of breath, fever sweating and poor appetite.
Antibiotics can keep an infected person from developing complications or spreading the disease to others. The sick passenger, however, was not taking medication.
The woman, a native of Korea who lived in Japan for the last 12 years, spent about a month visiting friends in Howard County before boarding United Flight 493 at BWI on May 11. In Chicago, she changed to United Flight 47, then landed in Hawaii so ill she was hospitalized immediately.
She died a week or two later, Dr. Castro said.
Puzzled officials said she apparently did not realize she had an active case even though she had been treated several years earlier for TB and was bedridden with a severe cough and other respiratory symptoms during her time in Maryland.
"The truth is that we don't know what the potential risk to $H passengers is, which is what prompts the investigation," Dr. Castro said. "Here's a person who didn't know she had active tuberculosis at the time she flew. We were able to confirm there was relatively extensive disease which accounted for her death within a couple weeks of her arrival."
In letters, the CDC is advising passengers to get a Mantoux skin test -- the more reliable of two TB tests on the market. In the test, a nurse injects a solution containing noninfectious pieces of tuberculin bacteria into the skin.
People who develop a large red welt are considered infected. They will probably be advised to take antibiotics to prevent a full-blown illness, said Sarah Bur, chief of tuberculosis control for the state Department of Health and Mental Hygiene.
Anyone who does not get a reaction, however, will probably be asked to take a second test several weeks later, she said. This is because a person can take up to 12 weeks to mount defenses against the bacteria -- and the test measures a person's immune response.
Dr. Castro said didn't know how many aboard either flight were from Maryland. The first plane, an Airbus A-320 had a seating capacity of 143. The second plane was a Boeing 747, carrying up to 393 people.
Members of the Howard County family remain free of symptoms and are receiving skin tests, according to local health officials.