Pets can be great friends. They're good listeners, they encourage you to exercise, and they're always on your side when you argue with your parents. But, like people, pets can carry infections, and sometimes these can be transmitted to people. Here's how you and your pet can stay infection free.
How Do Pets Spread Infections?
Some illnesses that pets get — such as feline leukemia, FIV, and heartworms — can't be transmitted to people. But pets can carry certain bacteria, viruses, parasites, and fungi that can transmit infections to people.
Infections from animals can be particularly dangerous to babies and young kids, pregnant women, elderly people, and people whose immune systems have been weakened by illness or disease (such as cancer or AIDS).
Zoonoses (pronounced: zoo-uh-no-seez) is the name for infections that can be passed from animals to humans. People get zoonoses when they are bitten or scratched or come into contact with an animal's waste products, saliva, or dander (flakes from hair, feathers, or skin).
Pets may also get ticks and fleas in their fur, and these insects can carry diseases — like Lyme disease or Rocky Mountain spotted fever — that may make humans sick.
Dogs and Cats
It's hard to believe that your canine companion or feline friend could be guilty of anything other than sleeping too much, but sometimes cats and dogs can pass infections to humans.
- Rabies is a severe illness caused by a virus that's carried in saliva. Rabies is passed to humans through the bite of an infected animal. Animals that may carry the rabies virus include raccoons, bats, skunks, coyotes, foxes, and groundhogs. Unvaccinated pets like dogs and cats can get rabies if an infected wild animal bites them.
Although rabies is a serious illness that can cause brain damage and death if not treated soon after exposure, cases of rabies in humans are extremely rare in the United States, thanks to pet immunization requirements. Domesticated pets, like dogs, should always be immunized (vaccinated) against rabies to decrease the possibility of infection.
Washing animal bite wounds thoroughly and immediately can help reduce the risk of rabies. If your doctor thinks you are risk for rabies after an animal bite, you'll probably receive a series of vaccines over a two week period.
- Campylobacter (pronounced: kam-pye-loh-bak-tur) infection is one type of infection dogs, cats, hamsters, birds, and certain farm animals can transmit to humans. Campylobacter is a type of bacteria that can live in the digestive systems of animals. People who come into contact with these bacteria can experience unpleasant symptoms like diarrhea (sometimes bloody diarrhea), abdominal pain, and fever.
Campylobacter infections most often happen when someone eats contaminated foods, such as undercooked meat or unpasteurized milk. Campylobacter also can be transmitted when people come into contact with an animal's feces (poop) or water that has been contaminated with the bacteria.
Campylobacter infections are contagious, which means they can be passed from person to person, especially among members of the same household. Doctors usually treat a Campylobacter infection with antibiotics.
- Bartonella henselae is the type of bacteria that causes what is known as cat scratch disease. A person who is bitten or scratched by a cat (or more commonly a kitten) that has been infected with the bacteria may develop swollen and tender lymph nodes, fever, headache, and fatigue. Usually, the cat doesn't show any symptoms at all, so you won't know if it is infected.
The symptoms of cat scratch disease usually resolve without treatment, but sometimes a doctor may prescribe antibiotics to clear up the infection. Cat scratch disease is not contagious from person to person.
- Dogs and cats with fleas may have several types of tapeworms. Dipylidium caninum is a type of tapeworm they can get from swallowing fleas when they groom themselves. Fleas can carry tapeworm eggs that grow into an adult tapeworm once they're in an animal's (or person's) system. Little kids are especially at risk of a getting tapeworm infection if they swallow an infected flea. Another type of tapeworm that can live in the small intestine of dogs, Echinococcus granulosus, can also infect humans.
People who have tapeworms may notice tapeworm pieces in their poop. (Pieces of tapeworm kind of look like grains of rice.) Doctors can give people medications to treat a tapeworm infection.
- Toxocariasis (pronounced: tok-so-kuh-rye-uh-sis) is an illness that is caused by parasite worms that live in the intestines of dogs and cats. The eggs from the worms are passed to humans through the feces of dogs and cats.
People who do not wash their hands frequently may accidentally eat the tiny eggs of these worms, which then hatch and develop in the digestive system. Babies and younger children who often put things in their mouths are particularly at risk of getting toxocariasis. Although pets can carry the worm eggs, most people who get toxocariasis do so through accidentally eating contaminated soil. They may have symptoms such as fever, cough, wheezing, abdominal pain, rash, enlarged lymph nodes, or eye disease. Medications can treat most forms of toxocariasis.
- A person gets toxoplasmosis (pronounced: tok-so-plaz-mo-sus) through contact with a parasite found in cat feces or undercooked meat. Signs and symptoms of this infection include swollen glands, fatigue, muscle pain, fever, headache, cough, sore throat, and rash. Toxoplasmosis is especially dangerous in pregnant women because it can cause severe problems for the developing fetus, including vision problems and mental retardation. Pregnant women should avoid all contact with litter boxes, especially those used by cats that go outdoors.
- Ringworm, also called tinea (pronounced: tin-ee-uh), is a fungal infection that can appear anywhere on a person's body. People can get ringworm from touching infected animals such as dogs, cats, and rodents — as well as from touching the infected skin of other people with the condition. Ringworm causes itchy circular rings anywhere on the skin (even the scalp) that continue to grow if not treated. Doctors use an antifungal cream or oral medicine to treat ringworm.
- Pasteurella bacteria are normally found in the mouth of cats and dogs. Bites and scratches from these animals can cause a skin infection called cellulitis, which can make the skin become red, warm, and tender, sometimes with pus. Cellulitis can cause complications like infection in the joints (septic arthritis) or in the bones (osteomyelitis). Doctors usually treat cellulitis with antibiotics.
Even if pet birds are kept in cages, they can sometimes pass certain infections to people. Fortunately, getting infections from birds is rare, especially if you are young and healthy.
- Psittacosis (pronounced: sit-uh-koe-sis), also known as parrot fever, is passed to people when they have contact with infected bird feces (poop) or with infected dust in birdcages. The birds that typically carry the organisms that cause the disease are parrots, parakeets, and macaws, but other birds like pigeons and turkeys also can transmit it. A person who has developed psittacosis may have a cough, fever, and chills. Doctors treat psittacosis infections with antibiotics.
- Cryptococcosis (pronounced: krip-tuh-kah-koe-sis) is passed on when people inhale organisms found in bird droppings, especially from pigeons and chickens. Symptoms include fever, fatigue, cough, and chest pain. Cryptococcosis can cause serious illness such as encephalitis (inflammation of the brain) and pneumonia. People with weakened immune systems from illnesses such as AIDS or cancer are at particular risk of getting cryptococcosis. Cryptococcosis is a type of fungal infection, so doctors treat it with antifungal medications.
Reptiles and Amphibians
Most reptiles and amphibians carry the bacteria Salmonella (pronounced: sal-muh-nel-uh) in their digestive tract and can be found on their skin. People who pick up Salmonella bacteria after touching reptiles (like lizards, snakes, crocodiles, and turtles) or amphibians (like frogs, toads, and salamanders) can become seriously ill.
Reptiles also can shed Salmonella in their feces, so people can become infected by touching a reptile's cage or other contaminated surfaces. Salmonellosis causes symptoms such as severe diarrhea, stomach cramps, and fever. It also can infect the blood and spread to other parts of the body. Antibiotics can be used to treat these infections, but aren't always necessary.
Even tiny creatures such as hamsters, gerbils, guinea pigs, and other rodents can carry diseases that may be harmful to your health. Most infections from these animals are passed to people through infected feces or a bite. These animals can also cause salmonellosis and ringworm in people.
- A very rare — but potentially serious — condition is lymphocytic choriomeningitis (pronounced: lim-fuh-sit-ik kor-ee-oh-men-in-jye-tis), or LCM. This infectious condition is caused by a virus that commonly infects mice, hamsters, and other rodents. People become sick with LCM from inhaling or ingesting the virus, which is found in urine, feces, or saliva of infected rodents.
A person who has LCM may have fever, fatigue, headache, muscle aches, nausea, and vomiting. About half of those infected will develop nervous system complications, such as meningitis (inflammation of the membrane surrounding the brain and spinal cord) or encephalitis (inflammation of the brain). There is no specific treatment for this virus, but people with LCM may have to be watched in the hospital until they recover.
- Tularemia (pronounced: too-luh-ree-mee-uh), also known as rabbit fever, is caused by the bacterium Francisella tularenis, which is carried by animals like rabbits, squirrels, and other rodents. It is extremely rare in the United States and is almost never caused by pets that have always lived indoors.
Tularemia is very infectious and people can get it by handling infected animals, inhaling the bacteria from contaminated soil, through tick or deer fly bites, or drinking contaminated water. It is not contagious between people, but pet cats can become infected and pass it on to humans.
Within a few days after exposure, a person can develop symptoms like skin or mouth ulcers, swollen lymph glands, headache, sore throat, and muscle pain. Pneumonic tularemia can cause symptoms like chest pain, cough, and shortness of breath, which can make a person very sick. Tularemia is treated with antibiotics and most people recover completely from it.
Keeping Yourself and Your Pet Healthy
Pets are popular. As many as 6 in 10 families in the United States have some type of pet, and numerous studies prove the health benefits of having pets, such as reduced stress and lower blood pressure. For some people, pets can be real lifesavers: companion animals help the blind and people with certain health conditions to live fulfilling lives.
But it is important to keep in mind that pets can carry diseases that can make you sick. Washing your hands often — especially after you touch, feed, or clean up after a pet — is the best way to keep yourself healthy and prevent the spread of infection. Use warm, soapy water and be sure to scrub under your fingernails every time you wash.
You also can protect your health even further by wearing gloves while cleaning animal cages or cat litter boxes. Avoid washing your pet in the kitchen sink or bathtub; but if you do, always disinfect it with bleach immediately afterward (the sink or tub, that is, not the pet!).
You can do a few other things to keep yourself and your pet healthy. Only give your pets food that has been formulated for them. It's not a good idea to share your food with your pet. Human food (like chocolate) can make animals sick. Never feed your pet raw meat because it can carry germs that cause serious illness — both for you and your pet.
And as funny as it can be to see your dog or cat drinking from the toilet, don't let pets do this. It's bad for your pet's health — not to mention your own if your pet comes up and gives you a big lick on the face afterward! Have clean, fresh water available at all times.
Be sure to bring your pet to the veterinarian for regular visits and whenever your pet is sick or injured.
Many infections caused by animals can be difficult to diagnose because the symptoms can be similar to other more common illnesses. If you're sick, be sure to let your doctor know if you've been around any sick or wild animals, or had any bites, including tick or mosquito bites.
Finally, some animals aren't pets. As tempting as it can be, don't take in a wild animal as a pet because it may be infected with diseases that could make you or your family sick. Instead, call an animal rescue group that is trained in helping sick or abandoned animals. And for your own protection, avoid touching strange animals or animals that appear sick.
Reviewed by: Yamini Durani, MD
Date reviewed: March 2012