Zoonosis – Do You Have to Worry About Catching Something From Your Pet?

This is our new puppy Maggie. We love her so much!

If you have spent any time reading my blog, then you have probably figured out that I love animals.  I have lived with them all my life and would consider my life empty without them.  I also firmly believe that pets are good for kids.  Pets teach children responsibility, allow them to experience the pride in taking care of something and children that grow up with pets have healthier immune systems.

While pets present few health risks to you or your children, there are certain diseases that humans can catch from pets.  Zoonosis refers to an infectious agent that is passed from animal to human or human to animal.  Zoonotic infections can include those passed from animal to human through an insect (called vector transmitted; such as Lyme’s disease carried by ticks) or those passed directly from animal to human.  Here I am just going to focus on the more well-known diseases (ok one is only really well-known by me) that can be passed directly from a pet to its owner.

Rabies.  I was traumatized by the book Old Yeller (by Fred Gipson) when I was younger.  In the book, a boy’s pet dog contracts rabies and has to be put down.  It was one of the first books that made me cry.

Rabies is probably the most well-known zoonotic infection and is caused by the rabies virus.  Rabies is transmitted via a bite from an infected animal.  Pets, such as dogs and large farm animals, can get rabies after being bitten by a wild animal that is infected with the virus. The infected pet can then bite their owners passing on the disease. Rabies is particularly scary for pet owners because it is almost 100% fatal in humans if not treated immediately after being bitten.

Thanks to pet vaccines (I think global vaccination for pets is a good idea too!), rabies is rarely a problem in humans, although it remains in wild animal populations.  A person can be successfully treated for rabies if treatment begins before any signs of symptoms.

Salmonella.  Another well-known disease is salmonella, caused by a bacterium that likes to live in the intestines of people, other animals and birds.  Most people are aware of food poisoning caused by salmonella which can be caught by eating raw eggs or poultry, or vegetables contaminated with fecal waste.  Salmonella can also be directly caught from pets.

Salmonella can be passed from most pets to humans, but is found more commonly in aquarium animals such as amphibians or in fowl, such as chicken and ducks.  The bacteria is found in feces and infection occurs through the fecal-oral route (think about it).

Salmonella causes diarrhea and abdominal cramping.  Thanks to your amazing immune system, the infection usually clears up on its own. However antibiotics can treat severe infections.

Toxoplasmosis.  Toxoplasmosis gives every pregnant woman the right not to change the cat litter box for 9 months.  Toxoplasmosis is caused by the parasite, Toxoplasma gondii, that is commonly found in cats.  In most people, infection with T. gondii causes a mild flu-like illness, or no illness at all.  In pregnant women though, T. gondii can cause a serious disease affecting the brain, heart, liver or eyes.

T. gondii is found in the feces of infected cats and can be ingested in dust particles, therefore it is recommended that pregnant women do not change litter boxes (yay!).  T. gondii is also ingested by eating undercooked meat from infected animals.

Infected people can be treated with drugs, although treatment often does not rid the body entirely of infection.

Parasites.  There are several parasites that can be transmitted from pets, mainly cats and dogs.  These include worms, and other parasites such as giardia.  One of the more infamous of these is the hookworm – the worm known to hook into children’s feet if they walk around barefoot outside (in contaminated feces).

Parasites live in people and animals and get their food at the expense of the host.  Symptoms of a parasitic infection in people can include muscle aches, fatigue, diarrhea and weight loss, depending upon the parasite. Cats, dogs and farm animals are routinely treated for parasites as they affect your pet’s health too.  Similar to salmonella, parasites are transmitted through the fecal-oral route.

Fortunately, most common parasitic infections in people are easily treated with medications.

Lymphocytic choriomeningitis virus (LCMV).  Wow – that’s a mouthful to say!  Most people haven’t heard of LCMV and there is a good reason for that.  Human infections with LCMV are pretty rare; infections caused by household pets are even rarer.

LCMV is found in small rodents such as mice, hamsters and guinea pigs.  Transmission occurs through inhaling dust from droppings or nesting sites or through a bite from an infected animal.  You have a greater chance of catching LCMV from wild mice inhabiting your home than you do from your guinea pig, but I thought I would mention this disease for 3 reasons: first, it’s caused by a virus and I love viruses,  second, I worked with LCMV when I was a post-doc and third, I previously wrote a post about guinea pigs, so I thought you should have this information as well.

Symptoms of LCMV in humans and pets range from no visible signs of illness to a flu-like disease, or a brain infection.  While rarely fatal in humans, LCMV can cause death in rodents.  There is no direct treatment for LCMV.

What can you do to prevent a zoonotic infection?  While a lot of these diseases sound scary, the chance that you would be infected by your pet are extremely rare.  To keep the odds in your favor, always wash your hands after handling pets or cleaning up after pets, keep your pets up to date on their vaccinations and treatments, only buy animals from reputable breeders and bring your pet to the vet for regular check-ups or when it is sick.

Teaching your children to follow these rules will teach them to be responsible pet owners.