The first time we had it I found out the same way. My daughter had been complaining about an itchy scalp, but she thought it was from some hair spray (color) that she used. We had never had it before so I was clueless. Didn't make the connection...
She was scratching her head and I saw the bugger LOL flip off her hair onto the couch. One look and I knew it. She was SSSOOO embarrassed that she had been scratching her head in school (7th grade). It was a very bad experience for her.