I would absolutely rather break the law than ask someone if they had AIDs before allowing them to work with food. If there's blood in the food, we don't sell it.
If they have a transmissible food borne illness, they are mandated to report it. They agree to report illness. We don't ask or guess if they are sick. We are mandated to give workers paid days off (at least in California) if they are working in the food industry for illness. If they're worried about not getting paid, they tell us, and we have them work on things that aren't food. There's plenty of break room trash can wall stains to scrub and fun safety training and SOPs to read.
This law isn't here for you to go digging through your employee's health history. It's here so when the next Typhoid Mary serves up some special soup you can test her for the strain and identify the source.
If you know there is blood in the product you don't sell it. If there is blood or other infected components in food that you don't know about you will put thousands to millions of people at risk and at some point if there is a massive outbreak linked to your facility you will go to jail.
You can't expect employees to do the right thing seeing as many times they don't even when they have been trained. That is why you are expected to be an active part of protecting your customers. That is why the laws and regulations are written the way they are. Persons infected with anything listed by the FDA are not afforded ANY protection in this matter.
That's the simple truth of the matter.