Its harmful to the baby mainly in the first tri, it can cause deformities, or the third tri, when they can be born with cp, and have to try and fight the disease themselves. I have no immunity, even though i had them twice (rather badly) as a child, and my son contracted cp when i was about 18w (very mildly) and i was fine.

JUst see you GP as the ladies have mentioned, but just think positive thoughts, you should be fine