For four years, my house was a healthy place. There was only an occasional allergy flare if I accidentally dusted or went outside when something was blooming. Having a cold, flu, virus, or stomach bug was something we had gratefully avoided for a while. At least, that is, until my child started school again. The first week or so, he came down with something. “He’s rebuilding his immune system,” I thought. I didn’t know he was rebuilding mine as well. A few days later, I came down with whatever crud he had.