3. You have a viral or bacterial illness that’s contagious. It can be hard to know if whatever you are experiencing is, in fact, a contagious illness, or just a bad case of allergies/exhaustion/hypochondria. If you aren’t sure, go to your doctor to get confirmation about whether or not you are infectious. And if you want to keep your illness from spreading from desk to desk in your office, keep it contained by confining your germs to your home.