The Tuberculosis Program in County Public Health Services (PHS), in collaboration with Metropolitan Transit System (MTS), is working to notify riders who used certain Trolley Blue and Green lines between February 16, 2023, and August 15, 2023, and bus riders and drivers who used Route 901 between April 22, 2023 and July 15, 2023, that they were potentially exposed and are at risk for tuberculosis (TB) infection.

The lines and routes impacted are:

  • Trolley Blue Line between Balboa Ave Transit Center and Old Town Transit Center, and on the Green Line between Fashion Valley and Old Town roughly between the hours 6 a.m. to 12 p.m. Monday to Sunday
  • Bus Route 901 from Iris Avenue Transit Center to Palm Ave. and 8th Street between 10 a.m. to 11 a.m. and 6 p.m. to 8 p.m.

Trolley exposures did not occur on a specific schedule. As such, many people may have had exposures, but the likelihood that any particular rider had long cumulative exposure times is low.

The chance of TB infection is highest for people with many hours of cumulative indoor exposure to a person who is sick with TB. Brief interactions with an ill rider are less likely to lead to TB infection than prolonged or repeated exposures. However, the risk from more limited exposures may be of particular concern to riders with compromised immune systems, from medical conditions such as HIV, or from medications that weaken the immune system, such as those taken by people with autoimmune conditions or who have received transplants.

While MTS follows CDC-recommended sanitation practices, TB is airborne and not spread by touch, so cleaning practices do not impact the risk of tuberculosis in transit vehicles or stations.

“Symptoms of active TB include persistent cough, fever, night sweats, and unexplained weight loss,” said Wilma Wooten, MD, MPH, County Public Health Officer. “Most people who become infected after exposure to tuberculosis do not get sick immediately. This is called latent TB infection. Some who become infected with TB will become ill in the future, sometimes even years later if their latent TB infection is not treated. Blood and skin tests effectively determine whether someone has been infected.”

People who test positive for TB but don’t have active tuberculosis symptoms should get a chest x-ray and talk to a medical provider, as they likely have latent TB infection. People in this situation are infected with TB, but the infection is essentially dormant or “sleeping.” Taking medicines for latent TB infection can cure the infection and keep these people from ever getting sick.

Individuals who want more information on this potential exposure should call the County TB Control Program at 619-692-5565.

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