Good rule of thumb. If you're running a fever, that's definitely a time to stay home because you're likely contagious. If a doctor has given you a course of antibiotics, that may stop the contagion, but let that be your doctor's call. If it's an allergy situation, you may just have to operate with it. Or if you're just going through a cold but aren't contagious and feel strong enough to work, you can get to work and avoid leaving your co-workers doing everything you were supposed to do.
Management needs to keep an eye out for repetitive sick calls.
That includes having sick children at home. If it's keeping parents from work too much, the employees who do come in are having to cover too often. Some attention from management may be needed. Supervisors need to show some muscle in these situations, that's part of the job. As long as we're talking about children for a moment, let's also mention the practice of bringing a sick child to work.