Your kid may be bringing home the bugs as quickly as some people bring home Cub Cadets but me thinks there are ways to combat the problem. Perhaps you could start looking good hygiene such as washing hands more often and using sanitizers. Even shooting up the house with disinfectant like Lysol. Perhaps you could look into bolstering your immune system by eating better and taking vitamins. I don't think being sick has to be that way. The same could be taught to your child and family.
Non of this take care of the Cub Cadet sickness, though.