Don’t let your dog lick the baby’s mouth. Don’t splash around in a pool of water where some critter may have just peed. And whatever you do, don’t pick an aggressive dog as a pal for your kids.
Beyond that – and a few other common sense things like washing your hands a lot – it’s fairly easy to live in domestic bliss, and health, with most pets, despite the more than 200 so-called zoonotic diseases, illnesses that animals can pass on to humans.
(It’s only fair to note that some diseases go the other way, from us to them. If you get the flu, for instance, your ferret – the yuppie pet of the 1990s – may, too.)
But for many people, especially parents of young kids, the big worry about sharing a home with animals is the risk of injury or disease that pets pose to people, not vice versa.
With nearly 60 percent of Americans households now owning pets – 60 million cats, 55 million dogs – the risk is real, though largely offset by the companionship that animals offer and the fact that many zoonotic diseases are treatable.
By far the biggest health problem with pets, says Dr. Ellie Goldstein, an infectious disease specialist at St. John’s Hospital and Medical Center in Santa Monica, Calif., is dog bites. They occur at the astounding rate of one every 40 seconds.
In 1994, that translated into roughly 4.7 million bites, says Dr. Jeffrey Sacks, an epidemiologist at the federal Centers for Disease Control and Prevention. That’s the most recent year for which the statistics have been compiled.
Most bites, of course, are minor, but 800,000 that year were serious enough to prompt people to seek medical care, Sacks says. In 1995 and 1996 alone, at least 25 people – 20 of them children – died from dog bite wounds. Half of the fatal attacks involved rottweilers.
Most people who suffer animal bites either know or own the animal, notes Goldstein, adding that many people are bitten on the hands while trying to separate two fighting dogs.
If a dog is rabid, of course, its bite can also transmit rabies – a viral infection that is fatal unless you are promptly vaccinated. You can also catch rabies from cats, raccoons, foxes, skunks, woodchucks and bats. And bats are the biggest culprits – though not too many people have them as pets.
Since 1980, 34 people in the United States have died from rabies, most of them from the types of rabies virus found in bats, says CDC epidemiologist James Childs. But most of these people did not remember being bitten by a bat or any other animal, so the exact chain of transmission is unknown.
Even when a dog bite isn’t fatal, serious infection can result because staphylococcus or streptococcus bacteria that normally live harmlessly on human skin get pushed deep into tissues, says Dr. Arnold Weinberg, head of the MIT Medical Department and a specialist in infections from animals.
But dog saliva contains more exotic bacteria, too, including Pasteurella multocida and Capnocytophaga, which, though treatable with antibiotics, can cause serious infections, especially in people whose immune systems are weakened.
Cat bites – which total 500,000 a year – can be even worse because cat saliva contains more Pasteurella. And because cats’ teeth are so sharp, a cat bite is essentially an injection of bacteria deep into tissues, even into bones and joints.
You can get Pasteurella from lions, too, though if you tangle with a lion, that’s likely to be the least of your problems.
Even cat scratches can be a problem. Cat scratch disease, caused by a bacterium called Bartonella hensalae, hits 22,000 people a year, says James Fox, director of comparative medicine at the Massachusetts Institute of Technology.
The Bartonella bacteria, which live in the cat’s bloodstream, get picked up by blood-sucking fleas on the cat’s skin. The cat then scratches the fleas, which leaves “flea debris” (a euphemism for flea feces) on the cat’s claws. If the cat scratches you, you get an injection of this bacterium into your skin.
Fleas also spread the bacteria from cat to cat, a major problem since American’s 60 million pet cats often come in contact with the 60 million wild cats in cities and towns.
Fleas from cats and dogs can also jump off their four-footed hosts onto you, causing a characteristic pattern of bumps in a row that some doctors dub “breakfast, lunch and dinner.”
Usually, a flea bite, at least with New England fleas, results in little more than an itchy spot. But swallowing a flea – this gets a little gross – can be more serious.
If your dog licks its fleas then sticks its tongue near enough to your mouth, you can get the flea. And if the flea is harboring tapeworm larva, you get the tapeworm, too.
Even cuddling has its risks – you can get a treatable skin fungus called ringworm if your cat or dog is infected.
Don’t panic, though. Despite all this, keeping a pet has been shown many times to provide important psychological and social benefits to children and adults alike. There’s just a tiny bit more unpleasant reality to confront – the miseries you can acquire from animal droppings.
Salmonella and camplyobacter – bacteria that cause diarrheal diseases in people – are easily spread via cat and dog feces, especially from puppies and kittens that have been in pounds or pet stores.
Iguanas, another trendy pet, also contribute their fair share to the salmonella problem, as do snakes and, historically, small box turtles. In fact, the risk to kids of playing with box turtles and plunging their hands in their soiled water was serious enough to prompt federal officials more than a decade ago to ban interstate commerce in the turtles.
Even good, old dirt in your gorgeous garden can spread infections, if neighborhood critters use it as a bathroom.
A major problem here is the droppings of cats and dogs, especially young animals, which may contain roundworm eggs called toxocara.
After two weeks in the soil, these become infective, says Dr. Leonard Marcus, a veterinarian and physician who is the liaison between the state medical and veterinary societies.
The roundworm parasite then migrates to different parts of the human body, causing disease which is hard to treat, though rarely fatal. In southern parts of the country, hookworm, also spread in contamined soil, is also a considerable problem.
Even pretty birds like parrots and parakeets cause their share of misery, notably a disease called psittacosis, caused by a chlamydia-like bacterium that lives in bird droppings. When the droppings dry out, the bacteria can become aerosolized, and you can inhale them while you’re cleaning the cage.
On the bright side, feline leukemia, a major problem for unvaccinated cats, does not spread to humans, nor does any other cancer seem to leap in either direction across the species barrier.
And you probably can’t catch ulcers from your cat, either.
Ulcers are usually caused by a bacterium called Helicobacter pylori. The bacterium has been found in one closed colony of cats and under experimental conditions has been shown to infect other cats. But so far, there is no evidence pet cats carry it, nor any evidence they transmit it to people, says Fox of MIT.
You might, however, be able to catch it from flies.
Dr. Peter Grubel, a medical resident at St. Elizabeth’s Medical Center in Boston, has shown that flies can pick up H. pylori from lab dishes and pass it in their feces. Whether people actually catch it from flies that have walked on infected human feces and then on food is not known but is certainly plausible, at least in the Third World, Grubel says.
But the bottom line, says Marcus, who has a private practice for two-footed, featherless creatures in West Newton, is that if you exercise common sense – and do a lot of handwashing – “the fun and benefits outweigh the risks of having pets.
“I strongly encourage people to own pets,” he says. “It’s an important part of regular living and a good experience.”
Previous “Health Sense” column are available through the Globe Online searchable archives at http://www.boston.com. Use the keyword columnists and then click on Judy Foreman’s name.
Some dos and don’ts
Doctors, veterinarians and federal disease control specialists offer the following tips for pet owners. For dog owners
- Pick an appropriate dog. Dogs with histories of aggression are inappropriate in households with children.
- If a child seems fearful about getting a dog, wait until the child is older.
- Spay virtually all dogs to reduce aggressive tendencies. If your dog does get in a fight with another dog, use your feet or a stick – never your hands – to break up the fight.
- Never leave a young child alone with any dog.
- Don’t play aggressive games with the dog.
- Teach children never to approach an unfamiliar dog and never to run away from a dog and scream. Rather, teach them to remain motionless if approached by an unfamiliar dog – the “be still like a tree” approach.
- Teach children that if they are knocked over by a dog, to roll into a ball and lie still – “Be still like a log.”
- Avoid direct eye contact with a dog; the dog may see this as a sign of your aggression.
- Let a dog see and sniff you before you pet it.
- Wash a dog bite wound immediately. Other tips
- Wash your hands and your child’s after handling any animal feces, including after your daily pooper-scooper/dog walk routine.
- Clean out the cat box at least every couple of days, preferably daily; try not to inhale the dust. Get someone else to clean the box if you have a weakened immune system or are pregnant. Cat droppings can contain toxoplasmosis, a protozoa that can lead to congenital defects in children and cause disease in immunosuppressed people.
- Wash vegetables grown in soil that might be contaminated by animal feces.
- Keep pets healthy – for their own sake and yours – by keeping regular veterinary appointments.
- Call your veterinarian if your pet seems sick.
- Be sensitive to a cat’s mood. When a cat says “no,” it really means it. Most cat bites occur if you try to snuggle with a reluctant cat.
- If you or your child comes down with a disease that stumps your physician, mention any potentially infectious animal contact.
- Respect your pet and interact appropriately.