Chris Kresser: It depends. Some parasites are horizontally transmitted easier than others. So, you know, the obvious one is pinworm, which can be a real pain in the butt if someone in the in the family has it. There are pretty good protocols just from the CDC on how to prevent transmission of pinworm. There’s some evidence that H. pylori, which, of course, isn’t a parasite but a bacteria, can be transmitted back and forth between couples and possibly between mother and children, certainly between mother and child early in life and in the birth process, but also possibly later through the family. Generally, with the exception of pinworm, we don’t treat other family members for parasite infections unless they have been tested and had been shown to be positive. In that situation, we would treat both people, and we don’t necessarily do any things special in terms of prevention unless they come back again and one or both re-acquires it. If that’s the case, then we look at pets. We look at family members, and we start looking more specifically at the routes of transmission for that particular organism, which varies from bug to bug, and then we make recommendations accordingly. A lot of that information is pretty readily available online and also a few resources like UpToDate.