Zoonotic Diseases in our Pets

The World Health Organization defines a zoonotic disease as an infectious disease that jumps from a non-human animal to a human. It can be a virus, bacteria, or a parasite and it spreads directly from animals, or indirectly through food, water, or the environment. There are over 200 known zoonoses. While wild animals and agricultural animals can spread zoonotic disease, we are focusing on our pets in this article.

Some common diseases that people could encounter from dogs and cats include (but are not limited to): parasites such as roundworms, hookworms, and some tapeworms; protozoal agents such as Toxoplasma and Giardia; sarcoptic mange (mites that cause scabies); ringworm (a fungal infection); bacteria such as Salmonella and Leptospira; and viruses such as Rabies and Avian Influenza. It is also important to point out that while your dog or cat will not directly give you Lyme disease (Borrelia burgdoreri), Bartonella, or the plague (Yersinia pestis), living with your pets could increase your chances of being exposed to those vector-borne diseases. 

Some of these diseases are transmitted by inadvertently ingesting the pathogens while others are transmitted by skin contact. Rabies is transmitted by infected saliva entering the blood stream or mucous membranes (i.e. mouth, eyes). Most of the time, a bite is the cause, but saliva entering scratches and other wounds can transmit the disease as well. Toxoplasmosis can be caused by eating undercooked meat such as pork or venison, but it can also be ingested from cat feces/litterboxes. Avian influenza can be transmitted from saliva or feces of infected birds getting into a human’s eyes, nose, mouth, or through inhalation.

Clinical signs can vary and cause a wide array of symptoms. Many of the intestinal parasites and bacteria will cause gastrointestinal signs in humans such as vomiting and diarrhea. Ringworm and mites will cause dermatological problems such as rashes and intense itching. Toxoplasmosis can cause general malaise, fever, and swollen lymph nodes. It can also be very detrimental to unborn children and people with compromised immune systems – neurological, digestive, and ocular problems have been reported. Miscarriages and congenital malformations can also occur in babies if a person is exposed while pregnant. Rabies can cause fever, behavioral changes, paralysis, and coma. Rabies is almost always fatal.

While all humans are at risk for zoonotic disease, those who are younger than 5 years, older than 65 years, those with weakened immune systems (on chemotherapy, have an immune disorders, or other infections), and those who are pregnant are at greater risk. In order to protect humans from these diseases, we focus on preventative measures. The most basic tool we have is good hygiene. Wash hands after handling pets, their waste, and their food. Keep beds, toys, and dishes clean. Using flea and tick prevention will help to prevent those vector-borne diseases, and heartworm prevention and deworming when necessary will help protect against some intestinal parasites. Avoid contact with wild animals to help avoid diseases such as mange, ringworm, and rabies. Vaccinations against Leptospirosis and Rabies also exist to protect humans.  Pets should be evaluated by veterinarians on a regular basis, but especially if they are new to the household and/or if they are acting sick.

For more information:
https://vcahospitals.com/know-your-pet/zoonotic-diseases-in-dogs 
https://www.cdc.gov/healthypets/specific-groups/veterinarians.html