When I was growing up, my work was with my family's business and the only time we got a sick day was when the whole family got norwalk virus, and even then I had to get back to work very quickly. If you don't know what that virus is, it's like the worst food poisoning of your life and it lasts at least two days. And it's highly contagious. I got it at the Opryland Hotel, and the hotel ended up calling the CDC because the outbreak was so bad.
Aside from that, we always worked when we were sick.