Pets have been shown to provide many benefits to human health. Stroking a dog has been linked to lower blood pressure and longer survival following a heart attack. What about dangers? Are we safe sharing our homes with dogs and cats? While the benefits of pet ownership far outweigh the risks, there are a number of diseases that can be transmitted from pets to humans. Physicians and veterinarians refer to these as “zoonotic” diseases. These diseases can be easily prevented with proper hygiene and preventative medicine.
Some examples of potential zoonotic diseases include:
Rabies
The best-known companion animal zoonotic disease is rabies. A virus affecting the nervous system of animals and humans, rabies is nearly always fatal once infection has occurred. All dogs and cats should be vaccinated regularly, as the virus is found in wild animal populations. Infected animals spread the virus through saliva via bites and scratches. Due in large part to enforced dog control, effective vaccination requirements, and post-exposure injections, deaths in humans due to rabies are rare in the United States. Many other parts of the world are not as fortunate.
Intestinal parasites
More common problems associated with pets include infection with intestinal parasites such as roundworms and hookworms. These intestinal worms are spread through feces and deposited throughout the environment. Because puppies and kittens can become infected before birth or through their mother’s milk, most newborn dogs and cats already carry roundworms. Because children play in dirt and sandboxes, put their hands in their mouths and don’t wash their hands frequently, they are most at risk for infection. Humans are not the natural host, so after entering the human body, the parasite “gets confused” and can end up in various tissues, including the eye. Roundworms are one of the leading causes of blindness in one eye in children. Infection with hookworms can occur by accidentally eating an infective larva, or by the larvae penetrating bare skin. The tracks left by these migrating parasites cause severe itching as well as gastrointestinal and other systemic diseases.
Toxoplasmosis
Toxoplasma gondii is a one-celled protozoan parasite found in the intestines in cats. While Toxoplasma can be associated with severe birth defects in infants whose mothers are infected for the first time while they are pregnant, contracting toxoplasmosis directly from cats is quite rare. The majority of human cases result from ingesting the infective stage of the parasite in raw meat or from the soil that clings to unwashed vegetables or hands after gardening.
When a cat sheds Toxoplasma in its feces, the parasite requires more than 24 hours to become infective to humans. Thus, cleaning the cat’s litter box daily before the cysts become infective, wearing gloves, and washing carefully after handling waste, are easy ways to prevent infection during pregnancy. There is no reason for pregnant women to part with their cats out of a fear of toxoplasmosis.
Ringworm
Ringworm has a parasite-like name but is actually a skin disease caused by a fungal infection. Dogs, cats, and many other animals can be carriers of this frustrating skin infection. It lasts in the environment for a long time, so reinfection or spread of infection through contact with the environment is common.
Salmonellosis
Salmonellosis is one of the most common infectious zoonotic diseases. Many species carry the Salmonella bacteria and may or may not show clinical signs. Infection with Salmonella causes diarrhea, vomiting, abdominal pain, headache, and fever. Spread through the feces, it most commonly affects children. Because reptiles and amphibians live in bedding and water that is contaminated with their waste, they pose a particular risk to those who handle them. Supervising children carefully when they are handling these species is important.
Prevention of zoonotic diseases
How can we protect ourselves from zoonotic diseases? The best prevention is good hygiene. Washing with soap and water after handling animals or their waste and before preparing food, eating, or smoking will decrease the chances of becoming infected. De-worming puppies and kittens starting at two to three weeks of age can break the cycle of roundworm and hookworm infection. Vaccinating your pets against rabies and other diseases can keep everyone safe. Keeping sandboxes covered and wearing gloves when gardening will limit one’s exposure to fecal waste. Using common sense and making sure your animals are in good shape will go a long way in keeping the whole family healthy and happy. For more information on zoonotic diseases, speak with your veterinarian or physician, or visit the National Centers for Disease Control [1].
Nancy Dreschel, D.V.M., Ph.D.- Pennsylvania State University
Related content:
- Keep Yourself and Your Pets Safe from Rabies
- Intestinal Parasites
- Understanding Toxoplasmosis
- Preventing Salmonella Transmission from Pet Foods
