California health officials urge anyone who has visited the Grand Casino in Pacheco since 2018 to undergo tuberculosis (TB) testing after several cases were detected among both the staff and visitors.

At least 10 cases of TB have been linked to the casino located in Pacheco, in Contra Costa County. However, the casino has not been identified as a current or ongoing source of transmission.

"Of the 11 confirmed TB cases, 10 are genetically linked and the majority are associated with staff or customers at the casino. The 11th case has not yet been genetically tested," Contra Costa Health (CCH) officials said in a news release.

Tuberculosis is a serious lung infection caused by a bacterium - Mycobacterium tuberculosis - that easily spreads in crowded places. The bacteria get transmitted through droplets when an infected person sings, coughs or sneezes.

The signs may not appear for months or years after contracting the bacteria, and the only way to detect is through a TB test.

Hence, those who suspect they have been exposed to TB, even if they have no symptoms, should undergo testing.

"If you believe you may have been exposed to TB, talk to your healthcare provider or call CCH's TB Client Services Program at 925-313-6740 if you are uninsured or need advice about the next steps," the release said.

Authorities have reached out to more than 300 people who may have been exposed to active TB and are working with the casino to promote testing among the staff.

"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, deputy health officer for Contra Costa County. "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."

Many people who contract TB infection may not develop the disease. However, young children, elderly people and those with compromised immune systems due to HIV, diabetes and severe kidney disease are at greater risk.

If not treated properly, the infection can cause complications such as lung damage, acute respiratory distress syndrome and TB meningitis and can become fatal.