SAN DIEGO — The County of San Diego Health and Human Services Agency is alerting some Metropolitan Transit System trolley riders they may have been exposed to tuberculosis.

MTS and HHSA officials are notifying riders who used certain blue and orange lines during a 6-month period between June 31 to December 31.

The county has announced the following lines are impacted:

  • Trolley Blue Line from San Ysidro to 12th & Imperial Transit Center, Monday through Friday from 6 a.m. to 6:30 a.m.
  • Trolley Orange Line from 12th & Imperial to El Cajon, Monday through Friday from 6:30 to 7 a.m.
  • Trolley Orange Line from El Cajon to 12th & Imperial, Monday through Friday roughly between 5:45 p.m. and 6:15 p.m.
  • Trolley Blue Line from 12th & Imperial to San Ysidro Transit Center, Monday through Friday roughly between 6:15 p.m. and 7:45 p.m.

According to the county, people with active TB often do not know they have TB and could be contagious before they are diagnosed with TB. The county reports they are typically alerted to a positive TB results after a medical provider’s test result. Then, communicable disease investigators interview the patient to get a better understanding of how long they were infected and where other people may have been exposed.

The county is advising people who were potentially affected to contact their medical provider or the San Diego County TB program.

TB is airborne and can be transmitted from person-to-person through bacteria in the air.

The county reports two other MTS riders with TB were reported in August and September 2022, but officials with HHSA do not have any evidence the most recently diagnosed rider is linked to the two others. The county said they are conducting additional lab testing.

The county said people with frequent and prolonged indoor exposure should get tested.

The county reports the number of people with active TB has stabilized and decreased since the early 1990s. The county said there were 208 people reported to have active TB in 2022, 201 in 2021 and 192 in 2020.

Those who believe they may have been exposed can take a TB risk assessment on the county’s website.

According to the county, people who test positive for TB but do not have any symptoms could have a latent TB infection where the infection is “sleeping.” The county says those individuals should still get a chest x-ray and talk to a medical care provider. The county reports that taking medication for a latent TB infection can cure it.