Yep. Breastfeeding passes your antibodies to baby, helping to protect her from sicknesses now and in the future. There’s no guarantee that you won't pass her an illness (through coughs, sneezes, and kisses — but not through your milk), but chances are good that baby has already been exposed to whatever ails you so it wouldn't make sense for you to stop now.
If there's something particularly nasty going around and you want to play it super safe, you can always pump some breast milk and have your partner feed baby until you feel better, or wear a mask over your nose and mouth while you’re in close contact with your child. Keep that breast milk flowing, though. It’s baby's best defense against the cooties.