Because the noro-virus is spread by human contact, the school is urging everyone to take precautions.
"I started feeling stomach cramps on Friday afternoon, and then I started throwing up around Friday evening," said Lauren, a USC student.
Andrew, another USC student, said the bug moved quickly through the swim team.
"It hit me around midnight on Saturday," he said. "Thought I could sleep it off because I just had a really bad stomach ache, but I woke up in the middle of the night just throwing up."
Campus health officials said they believe the worst of the outbreak may be behind them.