Thousands of San Francisco Bay Area residents may have been exposed to the measles last week when a University of California-Berkeley student infected with the virus rode on Bay Area Rapid Transit (BART) trains, reported SF Gate.
Health officials warn that anyone who rode on BART between February 4 and February 7 during the morning commute or late evening could have been exposed to the highly contagious respiratory virus, which can stay in the air for up to two hours. The unidentified student rode the train on Wednesday February 5.
Officials with Contra Costa Health Services suspect the student, who had not received a measles vaccination, was infected while traveling abroad.
Those who have been vaccinated or have already had measles are unlikely to be at risk.
"Measles is a serious, highly contagious disease," Dr. Janet Berreman, health officer for the city of Berkeley, said in a prepared statement. "It spreads through the air when an infected person coughs or sneezes. Fortunately, the measles vaccine is highly effective in preventing infection."
Anyone who shows symptoms such as high fever, runny nose and watery eyes should see their doctor.