(KRON) — Nearly a dozen cases of tuberculosis have been linked to a casino in Contra Costa County, public health officials announced Thursday. Anyone who spent time inside California Grand Casino in Pacheco within the past five years should take a TB test, according to Contra Costa Health Services (CCH).

“Recent genetic testing revealed several related cases among staff and customers over the past five years,” Contra Costa Health Services wrote.

CCH has so far not identified an ongoing source of transmission at the casino. Tuberculosis bacteria can live inside a person for months or years without causing any symptoms, health officials said.

“We are making this recommendation now because there is new evidence that TB may have spread among people who spent time at the casino from 2018 to 2023,” said Dr. Meera Sreenivasan, the county’s deputy health officer. “TB can live inside someone for years without showing signs of its presence. That is why it’s important to take a test, even if you do not feel sick. TB can cause serious illness, but it is treatable and curable with medicine, especially when caught early.”

CCH contacted more than 300 people who may have been exposed to tuberculosis. Eleven cases of TB were confirmed.

CCH is working closely with casino management to ensure appropriate testing and screening for casino staff members.

Symptoms of active TB can include a persistent or bloody cough, fever, unexpected weight loss, night sweats and fatigue, health officials said.

TB can spread when a person with symptoms coughs or breathes out droplets containing the bacteria, particularly in an enclosed space. The only way to know if someone was infected after a TB exposure is to take a test, health officials said.