Contra Costa Health Services said on Thursday that people in the San Francisco Bay Area may have been exposed to measles when a UC Berkeley student used BART to commute to class from Contra Costa County.
Officials confirmed the student had measles on Wednesday. The student had not been vaccinated, and was likely infected during a trip abroad.
CCHS said people who are vaccinated are unlikely to contract the disease even if they were in contact with a contagious person. Those who previously have not been vaccinated are likely catch measles if they are exposed.
"Measles is a serious, highly contagious disease," Janet Berreman, the health officer for the City of Berkeley, said. "It spreads through the air, when an infected person coughs or sneezes. Fortunately, the measles vaccine is highly effective in preventing infection."
The virus is able to stay in the air for up to two hours, and because BART cars rotate through the area, anyone who used the transit system from Feb. 4 to Feb. 7 during commute hours may have been exposed.
Symptoms of measles include high fever, runny nose, coughing and watery red eyes. A rash appears on the face and neck two to three days after the fever, and lasts for five or six days. A person is contagious for several days before and after the rash appears.
CCHS, the California Department of Public Health, UC Berkeley and City of Berkeley Public Health are investigating the case and notifying those who were in close contact with the patient. The agencies have not identified any other related measles infections.