San Francisco commuters possibly exposed to measles on trainSAN FRANCISCO  – Tens of thousands of commuters on San Francisco’s Bay Area Rapid Transit system may have been exposed to measles after an infectious Bay Area resident rode a train to and from work for three days last week, public health officials said on Wednesday. The rider represents the first case of measles confirmed by Contra Costa County health officials during an outbreak of the disease that began in late December. The infected person also spent time at a San Francisco restaurant and bar on the evening of Feb. 4. “Although the risk of contracting measles by being exposed on BART is low, Bay Area residents should be aware of the situation,” the county public health department said in a statement. The California Department of Public Health said on Wednesday that 110 cases of measles had been confirmed in California, many of them linked to the outbreak that authorities believe began when an infected person from out of the country visited Disneyland in late December. More than three dozen more cases have been documented in other U.S. states and in Mexico. Most people recover from measles within a few weeks, although it can be fatal in some cases. In the Bay Area case, the infected person was known to have traveled between the Lafayette station in the East Bay and the Montgomery station in San Francisco during the morning and evening rush-hour commutes on Wednesday, Thursday and Friday of last week, BART spokeswoman Alicia Trost said. That ride is 35 minutes long, but health officials said the highly infectious, airborne virus could have remained in the air for up to two hours. Because BART cars circulate throughout the Bay area, tens of thousands of people could have potentially been exposed, Trost said. More