Infections That Pets Carry

How Pets Spread Infections

Like people, all animals carry germs. Illnesses common among housepets — such as distemper, canine parvovirus, and heartworms — can't be transmitted to humans.

But pets also carry certain bacteria, viruses, parasites, and fungi that can cause illness if transmitted to humans. Humans get these animal-borne diseases when they're bitten or scratched or have contact with an animal's waste, saliva, or dander.

These diseases can affect humans in many ways. They're of greatest concern to young children, infants, pregnant women, and people whose immune systems have been compromised by illness or disease. Infants and kids younger than 5 years old are at risk because their immune systems are still developing, and some infections that might make an adult just mildly sick can be more serious for them.

Healthy Family, Healthy Pets

But you don't have to give up your family's furry friends either. Pets can enrich your family life, and taking a few precautions can protect your kids from getting sick.

Protecting your family from pet-related infections begins before bringing a pet home. For instance, reptiles and amphibians should not be allowed as pets in any household with infants and young children.

Also consider the health and age of your kids before getting a pet. A pet that would require frequent handling is not recommended for any immunocompromised child (such as a child who has HIV, has cancer and is undergoing chemotherapy, or uses prednisone frequently). Kids with eczema should probably avoid aquariums.

Dogs and Cats

Dogs and cats are popular pets but can carry infections such as:

• Campylobacter infection: can be transmitted by household pets carrying Campylobacter jejuni bacteria, which cause diarrhea, abdominal pain, and fever in people. The bacteria may be in the intestinal tract of infected dogs, cats, hamsters, birds, and certain farm animals. A person can become infected through contact with contaminated water, feces, undercooked meat, or unpasteurized milk.
  
  More than 2 million cases of campylobacter infection occur each year in the United States, and C. jejuni is now the leading cause of bacterial gastroenteritis. Campylobacter infections are contagious, especially among members of the same family and kids in childcare or preschools. Infection is treated with antibiotics.
• Cat scratch disease: can occur when a person is bitten or scratched by a cat infected with Bartonella henselae bacteria. Symptoms include swollen and tender lymph nodes, fever, headaches, and fatigue, which usually resolve without treatment. However, a doctor may prescribe antibiotics if the infection is severe. Cat scratch disease rarely causes long-term complications.
• Rabies: a serious illness caused by a virus that enters the body through a bite or wound contaminated by the saliva from an infected animal. Animals that may carry the rabies virus include dogs, cats, raccoons, bats, skunks, and foxes. Widespread immunization of dogs and cats has decreased the transmission of rabies in these animals and in people. Human rabies is rare in the United States, and a vaccine is available for treatment following a bite from a potentially rabid animal.
• Rocky Mountain spotted fever (RMSF): is transmitted by ticks infected by the Rickettsia ricketsii bacteria. Symptoms of RMSF include high fever, chills, muscle aches, and headaches, as well as a rash that may spread across the wrists, ankles, palms, soles, and trunk of the body. RMSF, which can be treated with antibiotics, is most common in the south central and the mid-south Atlantic regions of the United States.
• Ringworm: also called tinea; a skin infection caused by several types of fungi found in the soil and on the skin of humans and pets. Kids can get ringworm from touching infected animals such as dogs and cats. Ringworm of the skin, or tinea corporis, usually is a dry, scaly round area with a raised red bumpy border and a clear center. When the scalp is affected, the area may be flaky, red, or swollen. Often there are bald patches. Ringworm is treated with antifungal medications including shampoo, cream, or oral medicine.
• Toxocariasis: an illness caused by the parasitic roundworm Toxocara, which lives in the intestines of dogs and cats. The eggs from the worms are passed in the stools of dogs and cats, often contaminating soil where kids play. When a child ingests the contaminated soil, the eggs hatch in the intestine and the larvae spread to other organs, an infection known as visceral larva migrans. Symptoms include fever, cough or wheezing, enlarged liver, rash, or swollen lymph nodes. Symptoms may resolve on their own or a doctor may prescribe drugs to kill the larvae. When the larvae in the intestine make their way through the bloodstream to the eye, it is known as ocular toxocariasis, or ocular larva migrans, which may lead to a permanent loss of vision.
• Toxoplasmosis: contracted after contact with a parasite found in cat feces. In most healthy people, toxoplasmosis infection produces no symptoms. When symptoms do occur they may include swollen glands, fatigue, muscle pain, fever, sore throat, and a rash. In pregnant women, toxoplasmosis can cause miscarriage, premature births, and severe illness and blindness in newborns. Pregnant women should avoid contact with litter boxes. People whose immune systems have been weakened by illnesses such as HIV or cancer are at risk for severe complications from toxoplasmosis infection.
• Dog and cat bites: may become infected and cause serious problems, particularly bites to the face and hands. Cat bites tend to be worse, partly because they are deeper puncture wounds. Significant bites should be washed out thoroughly. Often these bite wounds require treatment in a doctor's office or emergency room; antibiotics are sometimes necessary.

Birds

Pet birds, even if they are kept in a cage, may transmit these diseases:

• Cryptococcosis: a fungal disease contracted when someone inhales organisms found in bird droppings, especially from pigeons, that can cause pneumonia. People with weakened immune systems from illnesses such as HIV or cancer are at increased risk of contracting this disease and developing serious complications, such as meningitis.
• Psittacosis: also known as parrot fever, a bacterial illness that can occur from contact with infected bird feces or with the dust that accumulates in birdcages. Symptoms include coughing, high fever, and headache. It is treated with antibiotics.

Reptiles and Amphibians

Reptiles (including lizards, snakes, and turtles) and amphibians (including frogs, toads, and salamanders) place kids at risk for:

• Salmonellosis: Reptiles and amphibians shed Salmonella in their feces. Touching the reptile's skin, cage, and other contaminated surfaces can lead to infection in people. Salmonellosis causes symptoms such as abdominal pain, diarrhea, vomiting, and fever. Young children are at risk for more serious illness, including dehydration, meningitis, and sepsis (blood infection).

Other Animals

Handling and caring for rodents — including hamsters and gerbils — as well as fish can place kids at risk for:

• Lymphocytic choriomeningitis (LCM): People can contract lymphocytic choriomeningitis virus by inhaling particles that come from urine, feces, or saliva from infected rodents, such as mice and hamsters. LCM can cause flu-like symptoms — fever, fatigue, headaches, muscle aches, nausea, and vomiting — and may even lead to meningitis (an inflammation of the membrane that surrounds the brain and spinal cord) and encephalitis (an inflammation of the brain). As with most viruses, there is no specific treatment, but some patients might require hospitalization. Like toxoplasmosis, LCM may be passed from infected mother to fetus.
• Mycobacteria marinum: This infection may occur in people exposed to contaminated water in aquariums or pools. Although mycobacteria marinum infections are generally mild and limited to the skin, they can be more severe in people with HIV or weakened immune systems.

Precautions When Adopting or Buying a Pet

If you're adopting or purchasing a pet, make sure the breeder, shelter, or store is reputable and vaccinates all of its animals. A reputable breeder should belong to a national or local breeding club, such as the American Kennel Club. Contact the Humane Society of the United States or your veterinarian for information about animal shelters in your area.

As soon as you choose a family pet, take it to a local veterinarian for vaccinations and a physical examination. Don't forget to routinely vaccinate your pet on a schedule recommended by your vet — this will keep your pet healthy and reduce the risk that infections will be transmitted to your kids.

You'll also want to regularly feed your pet nutritious animal food (ask your vet for suggestions) and provide plenty of fresh water. Avoid feeding your pet raw meat because this can be a source of infection, and do not allow your pet to drink toilet water because infections can be spread through saliva, urine, and feces.

Limit young kids' contact with outdoor pets that hunt and kill for food because a pet that ingests infected meat may contract an infection that can be passed to people.

Safely Caring for Your Pet

Here are some tips to help your family safely care for pets:

• Always wash your hands, especially after touching your pet, handling your pet's food, or cleaning your pet's cage, tank, or litter box. Wear gloves when cleaning up after an animal's waste, and if you have a bird, wear a dust mask over your nose and mouth when cleaning the cage to prevent inhaling urine or fecal particles. Don't have kids clean cages or litter boxes unless there is supervision or until they have demonstrated they can do this safely and responsibly (and again, hands should be washed afterward).
• Avoid kissing or touching your pet with your mouth because infections can be transmitted by saliva. Also, don't share food with your pet.
• Keep your pet's living area clean and free of waste. If your pet eliminates waste outdoors, pick up waste regularly and don't allow kids to play in that area.
• Don't allow pets in areas where food is prepared or handled, and don't bathe your pet or clean aquariums in the kitchen sink or bathtub. Wash your pet outdoors or talk to your veterinarian about professional pet grooming.
• Avoid strange animals or those that appear sick. Never adopt a wild animal as a pet.

Watch kids carefully around pets. Small children are more likely to catch infections from pets because they crawl around on the floor with the animals, kiss them or share food with them, or put their fingers in the pets' mouths and then put their dirty fingers in their own mouths. Also, if kids visit a petting zoo, farm, or a friend's house where there are animals, make sure they know the importance of hand washing.

For your pet's comfort and for your family's safety, control flea and tick problems in your pet. Fleas and ticks can carry diseases that may be easily passed to kids. Oral and topical medications are available for flea and tick control; avoid using flea collars because kids can handle them and become sick from the chemicals they contain. Check your pet regularly for fleas and ticks, as well as bites and scratches that may make them more susceptible to infection. Keep your pet leashed when outdoors and keep it away from animals that look sick or may be unvaccinated.

And, finally, spay or neuter your pet. Spaying and neutering may reduce your pet's contact with other animals that may be infected, especially if your pet goes outdoors.

Reviewed by: Steven Dowshen, MD
Date reviewed: February 2012
Originally reviewed by: Stephen C. Eppes, MD