I had impetigo. On my face and had to work serving in a restaurant. If I were the boss I'd have sent me home for a week to stop scaring the customers. My doctor wasn't concerned about me working with/near food.
He should have been! The guidelines used for exclusion by Environmental Health and advice to food businesses are at:
HPA guidelines
Fitness to Work
Impetigo is usually a staph aureus infection - look for the sections on that.
John