It can snowball out of control if your not careful.  My son’s teacher took it upon herself to explain to his class that he had a "medical condition" that compromised his immune system.  You guessed it, the next thing we new a child was telling the whole school he had AIDS!!!!  I was livid to put it mildly and the principal was very quick to remedy the situation as he understood the issues of liability.  It’s maddening though, because that teacher needed his medical info, but misused the information.