Can Your Pet Make You Sick?
Faithful felines and devoted dogs provide innumerable benefits to their owners, but sometimes they can spread infections to humans. There are several steps you can take to reduce the likelihood of contracting an infection from your pet.
With millions pets in United States homes, transmission of an infectious disease from pet to owner can occur. However, common sense and proper veterinary care can keep these occurrences relatively low.
"It's not one of the public health situations that are threatening the nation, by any means," says Peter Schantz, VMD, a veterinarian and epidemiologist with the Centers for Disease Control and Prevention (CDC) Division of Parasitic Disease. "However, the diseases are completely avoidable, usually by steps that are also protective of the pet."
Many infectious diseases tend to be specific to certain species. However, bacteria or parasites that live harmlessly or cause limited disease in one species may cause more serious illness in another.
What Can Pets Pass Along?
According to infectious disease specialist Dr. James S. Tan, animal bites present serious problems for people. If a wound is not cleaned and dressed properly or if medical care is not provided, the person is more likely to get an infection. Infections that may be passed from pets to people include:
Cat Scratch Fever
Cat scratch fever is caused by the bacteria Bartonella henselae, which healthy cats can carry. Cat scratch fever results after a cat scratches the skin, bites, or licks an open sore. About a week later, the point of contact develops a raised bump. Other symptoms may occur, like fever, fatigue, swollen lymph nodes, loss of appetite, or headache. Serious complications, like a high fever or pneumonia, may result.
Another infection that can result from contact with cats, toxoplasmosis poses the most danger to unborn children of women who do not have immunity or antibodies to the agent. Cats harboring Toxoplasma gondii, the causative parasite, may not show any symptoms but will shed spores in their feces. The spores become infectious within a day or two.
"Toxoplasmosis can cause congenital abnormalities or, later in the pregnancy, intellectual disability," says Dr. Tan. To play it safe, pregnant women and people with suppressed immune systems should let someone else empty the litter box.
Gastroenteritis can trigger diarrhea, fever, headache, and abdominal pain. Bacterial infections of the intestine from bacteria such as Campylobacter and Salmonella occur most often after people ingest contaminated food or beverages, however, this infection can also be passed from pets to humans.
Giardiasis is spread through ingestion of water or food that has been contaminated by feces containing the causative organism. "Children playing with puppies can get this one," Dr. Schantz says. Giardia is one of the most common intestinal parasites of pets and humans in the United States.
Ringworm is an itchy, fungal skin infection that can occur after contact with an infected pet.
Roundworms and Hookworms
These intestinal parasites can make the move to people through contact with contaminated dirt. "Roundworms need a couple of weeks to develop in the soil before they are infectious," says Dr. Schantz. "The infections occur when children share environments with pets, dogs, and cats." While hookworms enter the feet and cause intense itching, ingested roundworm eggs can make their way to organs and lead to serious complications.
A bite from an infected animal can cause rabies. You can eliminate this risk by having your pets vaccinated against rabies.
Take these steps to decrease the risk of getting an infection from your pet:
"If they take good care of their pets," Dr. Tan concludes, "pet owners should be all right."
Centers for Disease Control and Prevention
Humane Society International
Public Health Agency of Canada
2002 USPHS/IDSA guidelines for the prevention of opportunistic infections in persons infected with human immunodeficiency virus. JAMA HIV/AIDS Information Center. American Medical Association website. Available at: http://aidsinfo.nih.gov.
Cat scratch fever. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/healthypets/diseases/catscratch.htm. Updated June 23, 2011. Accessed September 29, 2011.
Preventing infections from pets: a guide for people with HIV infection. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/hiv/resources/brochures/pets.htm.
Tan JS. Human zoonotic infections transmitted by dogs and cats. Arch Intern Med. 1997;157:1933-1943.
Toxoplasmosis. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/parasites/toxoplasmosis/prevent.html. Updated June 1, 2011. Accessed September 29, 2011.
Zoonotic diseases. Humane Society International website. Available at: http://www.hsus.org .
Last reviewed October 2011 by Brian Randall, MD