I'm coming down with a cold and, as terrible as I feel, I'm headed to work. One reason is because I feel like if I can actually get out of bed then I can make it to work. Another reason is because, like so many of my co-workers, I just can't afford to take the time off.
I've gone to work with the flu, with an inflamed sciatic nerve and with stomach viruses among other things.
There's also a lot of pressure from your superiors to come in to work no matter how awful you're feeling. Never mind that you may be contagious to your co-workers as well as to the guests - ESPECIALLY if you handle food!