MARTINEZ (CBS SF) — Bay Area Rapid Transit riders may have been exposed to measles last week from a passenger traveling between the East Bay and San Francisco, according to public health officials.

The person is Contra Costa County’s first measles case since a statewide outbreak began in December.

Mountain View-based LinkedIn said the person is an employee at the business social-networking firm. LinkedIn also has offices in San Francisco’s Financial District.

The infected passenger traveled on BART before being diagnosed; anyone who is not vaccinated against measles is at risk to be infected if exposed to the virus, although county health officials said the risk of contracting measles by being exposed on BART is low.

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The passenger traveled between Lafayette Station and Montgomery Station in San Francisco from February 4-6 from during both the morning and evening commutes from 6 a.m. to 8 a.m. and 7 p.m. to 9 p.m.

The person was also at E & O Kitchen and Bar on 314 Sutter Street in San Francisco on the evening of February 4, between 5:30 p.m. and 7:00 p.m.

Contra Costa Public Health and the San Francisco Department of Public Health were working together to track the person’s movements and notifying people who were in close contact.

“Measles is circulating in the Bay Area and we don’t know yet where this person was exposed,” said Erika Jenssen, Contra Costa Health Services communicable disease program chief at a late morning press conference in Martinez.

Health officials said LinkedIn was cooperating with the San Francisco Health Department to ensure the safety of any employees who may have been exposed.

“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.

“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,” Jenssen said.

Word of new measles exposure comes almost one year to the day BART riders were warned about UC Berkeley student with measles who rode BART. The disease did not spread in that case, according to health authorities.

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