What is a zoonotic infection? This is a human infection acquired from an animal. These types of infections are not common in developed countries such as the United States, but there is enough risk to mention a few selected zoonotic infections and steps you can take to prevent them.

Roundworms and Hookworms

These intestinal worms are common in puppies and kittens. Some pets do not have any symptoms at all, while others may develop diarrhea, vomitting, or loss of appetite. In fact, many puppies acquire these worms from their mother before or immediately after birth through the mother’s milk.

Diagnosis involves examining a stool sample under the microscope, and these worms are usually easily treated. Most heartworm preventatives also have ingredients that will prevent dogs from becoming reinfected.

Hookworm and roundworm eggs are passed in the feces of affected dogs and cats. These eggs are too small to be seen except with the aid of a microscope. Once these eggs are passed through the feces to the ground, the eggs can survive for many months. There are no cleaners or detergents that work well to kill them.

Humans who come in contact with areas of ground that contain eggs can potentially become infected one of two ways:

  • Roundworms – these eggs may be accidentally ingested by placing one’s hand or other body part in the mouth if the body part has been in contact with the contaminated soil. This can lead to potentially serious internal organ or eye damage.
  • Hookworms – in the soil, these eggs hatch into immature worms called larvae. These larvae can burrow through exposed skin, such as feet, and cause inflammation of the skin.

Preventing human infection:

  • If you have a new puppy or kitten, bring your pet, along with a fresh stool sample, in to the animal hospital. The sample can be examined for parasite eggs.
  • Make sure your new puppy or kitten gets dewormed regularly according to your animal hospital’s protocol.
  • Keep your pet on monthly heartworm preventative, as this will prevent hookworm and roundworm infection.
  • Remove your pet’s feces from the yard and dispose of it as often as possible.
  • Cover sandboxes when not in use, these are a favorite for outdoor cats to use as a bathroom.
  • Keep children away from potentially contaminated areas of soil, grass, and gardens.


Toxoplasmosis is caused by a microscopic parasite called Toxoplasma gondii. This organism can infect virtually any animal, including humans. Pigs, rabbits, goats and rodents often become infected with this parasite. Therefore, if a cat were to hunt and eat a rabbit or rodent, it could potentially become infected with Toxoplasma. Likewise, a person who consumes undercooked meat (most often pork and goat) is at risk for Toxoplasmosis if the meat contains Toxoplasma eggs.

Another way to acquire the infection is to come in contact with the feces of infected cats. Cats are the only animals that pass Toxoplasma in their feces. Thus, if any eggs are in the feces when the cat uses the litter box, a person cleaning the litter box could potentially get the eggs on his/her hands. If the person accidentally puts his/her hands around the mouth, it is possible to swallow Toxoplasma eggs. However, the feces must be at least one day old before the eggs are capable of infecting any animal or human. This is very important to remember because it means that if you clean your cat’s litter box daily, there is a very low risk of contracting Toxoplasmosis. If a cat does become infected, it usually only passes eggs in its feces for 2 weeks and never again after that.

Only those women who become infected during pregnancy are at risk for abortion and fetal birth defects. Most people, who are infected, eliminate the infection within 12 weeks, and they then have antibodies in their blood that protect them from further infection. A woman, who has protective antibodies before she is pregnant, is not at risk for harming her fetus during pregnancy. A woman who has no protective antibodies is at risk, and there are several steps that can be taken to prevent infection.

  • The overall risk of contracting Toxoplasmosis is extremely low.
  • Keep your cat indoors at all times. Indoor cats cannot hunt other animals. This prevents the risk of becoming infected by eating a rabbit or rodent.
  • If you are pregnant, have someone else clean the litter box. If this is not possible, wear gloves when cleaning the litter box and wash your hands afterward. Remove feces from the litter box once daily.
  • It is perfectly safe to hold and pet your cat. If your cat goes outside, you should probably wash your hands after handling it.


This bacterial infection affects a large variety of animals including cats and dogs as well as humans. It is spread via the urine of affected animals. Contact with water, soil, or the affected animals’ bodily fluids can transmit the disease. Leptospirosa has the ability to even penetrate the through the skin. The animals most frequently implicated as a source of infection for dogs and humans include: rodents, deer, raccoons, opossums, and squirrels.

In dogs, symptoms of this infection include: lack of appetite, high fever, vomitting, soreness, and weakness. This is a treatable disease, but it can sometimes lead to chronic liver and kidney disease, as those organs are frequently targeted by the bacteria. There is a vaccine to prevent this disease. There are 7 different types of Leptospirosa bacteria, and the vaccine only protects against 4 types, but because of the serious nature of this infection, and the fact that it is a zoonotic disease, vaccination is extremely important.

A person can acquire this disease by coming in contact with the same contaminated water or soil, or by handling affected wildlife or pets. If your pet has been diagnosed with this infection there are several precautions you should take.

  • It may be wise to consult with your physician as to whether or not you should take antibiotics for this infection just in case.
  • Do not come in contact with any blood or urine as these are a source of infection.
  • If you must handle your pet, wear gloves and clothing you can quickly remove and wash in bleach.
  • Using one part bleach in 10 parts water is an effective way to kill the bacteria on any surfaces.
  • For more information on these topics visit The Center for Disease Control website at www.cdc.gov