Q: How can you tell whether you have a stomach virus or food poisoning, and what do you do for each?

— Lori, West Hills, Calif.

A: A stomach virus and food poisoning are tougher to tell apart than twin tigers at two miles. They have the same symptoms — that dynamic duo of vomiting and diarrhea — and the same danger (dehydration, which can be life-threatening). When either is relatively mild, you don't really need to know which is which, except to remember which restaurant not to go back to. They're treated in the same way: fluids to replace what you've lost, rest, giving your stomach a break and then easing into easily digestible food, such as gelatin, rice, bananas or chicken.

But if your symptoms last for several days, especially diarrhea, blood or mucus in loose stools, or if you develop a fever, the time for keeping matters in your own hands has passed. You need to see your doctor: It could be food poisoning, a norovirus (the cruise-ship "flu") or even an infection from bacteria or a parasite (which also can come from something you ate). Any one of them has the potential to send you to the hospital for IV fluids and drugs or worse if you wait too long.

Q: I have a cat and a 15-month-old daughter. My neighbor told me to worry about the germs the cat may carry on to the carpet or tile floor from his cat box to my daughter. Are there any serious germs to worry about?

— Anonymous

A: Put away the Lysol (it will ruin your carpets anyway). Your cat and your toddler should be able to coexist peacefully as long as she's not treating the litter pan as her personal sandbox. Cats aren't particularly germy, but there are a few diseases they can pass along to humans, especially babies. Toxoplasmosis, for example, is a parasitic infection that cats can pick up by eating infected rodents or birds. It causes flulike symptoms in humans, but if a child is infected before birth (through the mother), exposure can lead to vision loss, seizures and mental disability. Following a few simple rules should keep the whole family (cat included) safe:

Don't allow your cat and kid to be alone together — at least until your child is age 5. Not gonna happen? At least make sure your child doesn't kiss the pet on the lips or put their hands in their mouths after handling the animal. If a fight breaks out, clean up bites or scratches and apply antibiotic ointment.