Bay Area residents in California may have been exposed to measles a week ago after an infected rider traveled aboard the Bay Area Rapid Transit (BART). City officials have told residents to be aware of symptoms as they conduct their investigation.

In a press release from Wednesday, officials from the San Francisco Department of Public Health announced an unnamed rider infected with measles had used the BART trains on Wednesday, Thursday and Friday, February 4-6 during the commuting hours of 6 a.m. to 8 a.m. and 7 p.m. to 9 p.m. He or she traveled between Lafayette Station and Montgomery Station. The release explained this was Contra Costa County's first measles case and officials were investigating the person's movements.

The press release also noted that the infected person had gone to E & O Kitchen and Bar on Wednesday Feb. 4. They warn anyone who attended the locale between 5:30 p.m. and 7 p.m. may have been exposed, adding that the owners were cooperating with officials.

They warn that the disease is a highly contagious disease spread through the air when someone sneezes or coughs. Anyone who shows symptoms, which include fever, coughing, runny nose, conjunctivitis (pink eye) and a rash, should contact their doctors.

"Measles is circulating in the Bay Area and we don't know yet where this person was exposed," said Erika Jenssen, Communicable Disease Program Chief with Contra Costa Public Health. "The ongoing measles outbreak in California highlights the need for people to be vaccinated, and this is just another example of how interconnected our region is and how important it is for everyone to be up to date on their immunizations."

CBS San Francisco reports the infected person is a LinkedIn employee. The company is based in Mountain View but has an office in San Francisco's Financial District. LinkedIn says it is cooperating with health officials.

"The health and well-being of our employees is our absolute top priority, and we will take whatever steps are advised to ensure their safety and the safety of the general public," LinkedIn said in a statement.

According to Reuters, the virus can remain in the air for about two hours, exposing thousands who are not vaccinated, said health officials. There are around 110 cases in California, the California Department of Public Health reported.