Ashley Lee thought it was just the flu coming on. A little headache, an upset stomach — nothing to skip a hometown frat party for, reasoned the 18-year-old as she cruised the 90 miles from Indiana University in Bloomington back home to Terre Haute, Ind.

But at the party, the college freshman ran to the bathroom to vomit every half hour and eventually headed home, where her parents figured she'd feel better after a good night's sleep. The next day, she collapsed on her way to the bathroom. Her dad carried her to their car, and they sped toward the local hospital. At the emergency room, she lost her vision for several terrifying seconds.

"That scared me half to death," Ashley says. "I knew something wasn't right."

Hours later, Ashley was diagnosed with meningococcal meningitis, a rare but potentially deadly bacterial infection.