Home Sick

Why do my coworkers insist on coming to work when they are sick? They leave used tissues scattered across their desk. They cough and sneeze into their hands and proceed to touch every doorknob and drawer handle in the office. Before long the whole office ends up sick. I think it's because they used their sicktime up when they were not sick and just wanting an extra day off. Yikes people, keep your germs at home.