Health officials have issued a tuberculosis alert to passengers of a commercial bus that traveled through New Mexico from Texas to Colorado in August.

The New Mexico Department of Health said Tuesday a person recently diagnosed with infectious tuberculosis was a passenger on the bus Aug. 3 and Aug. 9. Only passengers who rode the bus with this person are at risk for being exposed.

The bus, chartered by El Paso-Los Angeles Limousine Express, Inc., left El Paso, Texas, the morning of Aug. 3. The person with TB boarded the bus later that day in Albuquerque and continued on to Greeley, Colo.

The person returned to Albuquerque on the same bus line Aug. 9, health officials said.

Chris Minnick, a spokesman with the New Mexico Department of Health, said passengers who were on either of the two buses should contact their local health officials for instructions on what to do.

"We're most concerned about getting the passengers to call in to be treated," he said.

Dr. Marcos Burgos, the state health department's TB medical director, said people often delay seeking care and may be ill with symptoms for weeks or months before TB is diagnosed.

"People can expose others to tuberculosis without knowing they have the disease," Burgos said. "During the contact investigation, which requires several interviews with the case, we identify all the possible individuals who may have been exposed to TB. It is not unusual for people exposed to be notified weeks or months later of their potential exposure."

TB is caused by germs that can be spread from one person to another when a person with active TB coughs, sneezes, speaks or sings. Anyone sharing air for prolonged periods with a person with infectious TB can breathe TB germs into their lungs.

Minnick could not say how many people may have come in contact with the person during the two bus trips. Health officials said although the risk of TB infection from exposure on a bus is considered small, it's important that passengers be evaluated.

Minnick said a medical evaluation may involve a skin or blood test and possibly a chest X-ray. New Mexico has had 54 TB cases so far this year.