you have to actually INGEST the virus, which means if he didn't wash his hands, whether the v* or had d*, and then you touched the surface he did with his dirty hands and then put your hands in your mouth or ate without washing your hands, you can contract it. Hopefully, he washed his hands after episodes of v* and d*? If he's getting sick that often, maybe be should look into some vitamins? Washing his hands more?