A UC Berkeley student may have exposed thousands of San Francisco Bay Area commuters, as well as fellow students, to measles after he took public transportation and attended class while infected.

The student, who was not identified, took a Bay Area Rapid Transit train from his home in Contra Costa County to the college campus to attend class, officials said.

Health officials said the measles virus can stay in the air for up to two hours, so anyone who rode BART during the morning commute hours or in the late evening from Feb. 4 to Feb. 7 may have been exposed.

“Measles is a serious, highly contagious disease,” said Berkeley’s health officer, Dr. Janet Berreman. “It spreads through the air when an infected person coughs or sneezes. Fortunately, the measles vaccine is highly effective in preventing infection.”

In a news release posted on the city of Berkeley’s website, officials said they believe the student was not vaccinated and likely contracted measles during a recent trip abroad.

“Before being diagnosed, the student spent time in the Berkeley community, including attending classes and using BART on several days,” according to the news release.

UC Berkeley health officials said they contacted the 100 students who shared a class with the infected student.  The university also ordered 300 doses of measles vaccine so people who wanted to get their shot could do so.

Anyone who shows symptoms should immediately see a health professional, officials said.  Symptoms, which can begin one to three weeks after exposure, can include high fever, watery red eyes and a rash that often occurs on the person’s face and neck a couple days after the fever starts before spreading to the body.

People who have already had measles or got the vaccine are unlikely to become infected, health officials said.

So far, no other cases have been identified, but officials said they are still investigating the situation.

According to the Centers for Disease Control there were 189 reported cases of the measles in 2013.