BART riders commuting to San Francisco may have been exposed to measles, public health officials are warning after a passenger tested positive for the infectious virus.
The infected rider worked in LinkedIn's San Francisco office and traveled between there and Lafayette during the morning and evening commutes from Feb. 4 to 6, according to the Contra Costa County Public Health Department and a company official.
LinkedIn released a statement after it learned the traveler was a company employee.
"We are working very closely with the San Francisco Department of Public Health, and following their recommended protocol for managing this situation," a LinkedIn spokeswoman said.
"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."
County officials say the danger of contracting measles on BART is low for vaccinated riders, but those who were not vaccinated are at high risk.
"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 measles virus can stay in the air for up to two hours, so anyone who rode BART during that time is at risk, health officials say.
The rider is the county's first confirmed case of measles during the current outbreak.
The county's public health department and the San Francisco Department of Public Health are looking into the infected rider's movements and are notifying those known to be in contact.
Public health officials say the rider visited E&O Kitchen and Bar in San Francisco between 5:30 p.m. and 7 p.m. on Feb. 4.
"While we are concerned about the current outbreak in California and its potential to spread, we cannot emphasize enough that the solution is simple and available: be vaccinated," said San Francisco Health Officer Dr. Tomas Aragon.
Measles is spread through the air when an infected person coughs or sneezes.
Symptoms for measles can appear one to three weeks after being exposed to the virus. A person infected with measles exhibits a high fever, a full body rash, coughing and a runny nose.
The number of measles cases linked to the California outbreak rose Wednesday to at least 136. It has been found in 12 California counties, seven other states, Mexico and Canada.
Of those cases, 110 were in California and at least 39 were linked to visitors or employees who went to Disneyland between Dec. 17 and 20.