No person suffering from a communicable disease transmissible through food or drink, or who resides in a household with a case of such disease, or who is known to be a carrier of the organisms causing such disease, and no person suffering from a local infection transmissible through food or drink shall be employed in any restaurant or itinerant restaurant. All employees of restaurants shall be subject to periodic health examinations for the purpose of detecting any communicable diseases transmissible through food or drink. All employees shall wear clean garments and shall keep their hands clean at all times while on duty in a restaurant.