They're constantly moist and full of tiny food particles. Using that sponge to clean the kitchen spreads filth everywhere, says Gerba. Disinfect your sponge each night by soaking it in a cup of water mixed with a few teaspoons of bleach. After you wash your hands, make it a habit to use a paper towel to shut off the faucet and open the door. Granny, however, is exempt from this law.
Botulism is rare, but it can be fatal.
Persuade her not to can beans, which are most vulnerable to clostridium, and to stick to acidic foods such as tomatoes and pickles, which are naturally antibacterial. But shake his hand and rub your nose an hour later, and the next day you'll be a mucus factory. But don't reject a proffered hand. Better to be polite and risk the sniffles than to be healthy and universally disliked. The wet, well-traveled floor is a campground for the dermatophyte fungus that causes athlete's foot.