My cat is a sweetheart. But 3 years ago, Atticus got lost, and by the time I found him, he was so terrified that my kissy noises didn't matter: He bit me. I immediately washed the wound and put on antibiotic ointment, but the bite got infected anyway. In fact, the doctor said I risked gangrene; I almost ended up in the hospital.

Atticus is purring next to me right now. Still, while a pet brings joy and companionship to your life, he can also bring scary bacteria, worms, and disease-causing bug bites. "Fortunately, with all the preventives and treatments, there is no reason for anyone to become infected with these diseases," says Michael Paul, DVM, executive director of the Companion Animal Parasite Council.

Here's how to stay safe.

Dirty Dangers

Animals shed worms and other intestinal parasites through their feces. Even poop scooping may not stop transmission, because a single roundworm on the ground can produce 100,000 eggs. And some types of parasite eggs can survive for years in dirt or sand.

Children are more likely to get infected than adults: Picture a toddler playing in the yard; now imagine her putting her fingers in her mouth. Roundworm can be a very serious parasite-in rare cases, it can cause blindness. Another danger: the parasite that causes toxoplasmosis.

OB/GYNs typically tell pregnant women to pass the litter box-cleaning duties to their partners because of this risk. (Toxoplasmosis can be picked up from cat feces in the litter box or outside in the garden dirt.) It's usually asymptomatic, but if a woman becomes infected while pregnant, she can give it to her unborn child, who may suffer brain damage, eyesight problems, or mental retardation.

Finally, Salmonella and E. coli bacteria can cause potentially dangerous intestinal infections if you unwittingly touch waste from any animal, including those at farms and petting zoos.

Protect yourself Teach your children to wash their hands after playing outside or rolling around with the puppy. (Bring hand sanitizer to the petting zoo.) Keep kids away from areas where animals may have roamed, including uncovered sandboxes. Wear gloves when gardening or cleaning up animal waste, and wash up afterward. Have your vet regularly check your pet for worms.

Don't Get Bugged

Ticks and mites can make pets sick and cause potentially serious diseases, such as Lyme disease and Rocky Mountain spotted fever, in humans, too. Symptoms may include rash (often a telltale bull's eye shape in Lyme), fever, muscle pain, nausea, vomiting, and headache.

Protect yourself Ticks are anywhere deer and small wild animals are found, including suburban areas, so check your pet thoroughly when he comes inside. Use flea and tick products, but be aware that they won't get all the critters. Look yourself over, too, after examining your pet.

Nasty Nibbles

Every year, several million people are bitten by animals-often their own pets. Obviously, that hurts. Not so obvious: As many as 50% of cat bites and 25% of dog bites become infected, sometimes with serious consequences.

Protect yourself Seek immediate medical care if you're bitten or scratched; even a minor cat puncture wound can get infected. Wash scratches and bites thoroughly with soap and water and apply antibiotic ointment.

Happy Pet, Happy Human

Your first line of defense is to keep, your animal in good shape. Make sure he's clean, well-fed, and exercised, and schedule well-pet exams twice a year. "A healthy pet will repel parasites naturally," says Marty Goldstein, DVM, author of The Nature of Animal Healing.

Susan T. Lennon is a Connecticut-based writer.