Toxoplasmosis is an illness caused by one of the most common parasites in the world – Toxoplasma Gondii. All warm blooded vertebrates (including humans) are potential hosts for this microscopic parasite, but only cats can help it complete its life cycle.  According to the CDC  more than 60 million humans in the U.S. alone may be infected.

The Life Cycle of Toxoplasma Gondii

  1. Eggs called oocysts are deposited on the ground in cat feces. It will take those oocysts up to 5 days before they become capable of infecting an animal. At this point they may be ingested by an intermediate host such as a bird, rodent, cow, or chicken who eats contaminated soil or plants.

    Toxoplasmosis LIfe Cycle

    Life Cycle of Toxoplasma Gondii
    Photo Courtesy of the CDC

  2. Once the oocysts are ingested, digestive agents in the host’s digestive tract will open the oocysts and the parasites will emerge.
  3. The parasites enter host cells and form a protective layer around themselves.
  4. From within this protective layer, the parasite will duplicate itself every 6-12 hours. It will continue to multiply until it overwhelms it’s protective layer and then it will continue multiplying within the host cell until it i bursts and the new parasites are released to find new host cells. A person or animal is considered to have Toxoplasmosis when the Toxoplasma Gondii parasites are actively multiplying with in them.
  5. A cat ingests something that is infected with Toxoplasma Gondii; soil, plants, or an intermediate host such as a bird or mouse.  The parasite goes through all of the stages above, but also a reproductive phase which leads to the creation of new oocysts.  These new oocysts are excreted in the cat’s feces to begin the life cycle again. Cats can excrete these oocysts for up to 3 weeks after infection.

Before You Start to Panic

Toxoplasmosis Microscopic view

Toxoplasma Gondii under a microscope.
Photo courtesy of the CDC

Unlike many other parasite infections, Toxoplasmosis is not that big of a problem for animals and humans who are otherwise healthy. Most people and animals infected with Toxoplasma Gondii never have any symptoms. Some people who have healthy immune systems may have mild flu-like symptoms that are short lived. Cats with healthy immune systems may experience mild diarrhea and loss of appetite. A healthy immune system is able to keep those parasites under control and their replication never makes it to the point  of causing damage to the host. This is an illness that may have come and gone without you ever knowing it. 

Those for whom Toxoplasmosis is the most worrisome are those with impaired immune systems and pregnant women.  If your immune system can not control the replication of the parasite, Toxoplasmosis can become very serious. At certain stages the parasite can be transmitted to a baby growing inside its mother (the same is true of a mother cat and her kittens). Due to the baby’s inexperienced immune system, the parasite can cause a lot of damage. Most babies born with Toxoplasmosis have no symptoms at birth, but may develop them later in life.

Don’t get rid of your cat! That cat is perfectly safe to keep – even if you have an impaired immune system or are pregnant . It is true that humans can become infected with Toxoplasma Gondii after touching cat feces, but this is seldom the way infections occur in humans. Toxoplasma Gondii can not be absorbed through the skin, it must be ingested. Most frequently, humans with Toxoplasmosis became infected through unsanitary handling infected food or eating uncooked meat or unwashed vegetables . 

Symptoms and Diagnosis

In humans, Toxoplasma Gondii likes to take up residence in muscular tissues and the tissues of the nervous system (in cats the lungs, liver and nervous system are most at risk). Those who do happen to develop a severe case of Toxoplasmosis may experience shortness of breath, neurological conditions like seizures and loss of balance,  reduced vision,  and red, tearing eyes. Some new research is showing that there are connections between certain mental illnesses and Toxoplasmosis. Schizophrenia has shown many positive corralations to Toxoplasmosis. This research, however, has not yet determined whether Toxoplasmosis can cause any mental illness or not.

There are tests for both humans and pets available to test for Toxoplasma Gondii infection. These tests look for the anitbodies that your body creates in response to the infection. Doctors and veterinarians can determine whether there is a past infection or a current infection. Antibiotics are sometimes used to treat the infection though they do not kill the parasites. Methods of dealing with a current infection in pregnant women are available. Cats found to have a current infection should be kept away from people with compromised immune systems or pregnant women just until the period that they could pass the oocysts in passes.

Preventing Toxoplasmosis

There are a lot of simple things that you can do to prevent Toxoplasmosis. For the most part good hygiene can keep you parasite free.

  • Obi Wan and Fish SticksMake sure that meat is thoroughly cooked to kill parasites that may be in it. DO NOT consume under-cooked meat.  Fight Bac is a website recommended by the CDC that lists proper temperatures for food preparation. Be aware that feeding your cat raw meat puts them at risk for infection as well. Freezing meat for 24 hours will also kill Toxoplasma Gondii.
  • Wash your veggies before you eat or cook with them.
  • Keep your cat indoors. The animals that your cat may hunt and eat outside could spread the infection to your cat.
  • Wash your hands, cutting boards, knives, counters, and other cookware after they have touched raw meat.
  • Wear gloves and/or wash your hands after cleaning your cat’s litter box.  Wearing a protective face mask may be helpful too so you don’t breathe in any of those microscopic organisms. If you have a compromised immune system or are pregnant, try to have someone else clean the litter box if possible.
  • Clean the litter box frequently. It takes a couple of days for those oocysts to become infectious after they have left the cat’s body. Removing them from your home before they are infectious will help lower risk of infection.
  • Wear protective gloves when gardening. This will keep you from picking up any of the oocysts that may be on the ground or on the plants.
  • Cover back yard sandboxes. Keeping them covered helps to keep them from becoming a litter box for the neighborhood cats.