What Is Toxoplasmosis?

Toxoplasmosis is an infection caused by the parasite Toxoplasma gondii which can infect many animals, including man. Toxoplasma occurs worldwide. Most infections are silent and have no ill effect on the patient; however, occasionally infections can be devastating – in immuno-compromised patients, for instance.

Routes of Infection

Humans become infected when they eat undercooked mean in which Toxoplasma cysts are present. They may also become infected if they ingest oocysts from cat feces. The parasite passes one stage of its life cycle in the gut of cats and another stage of its life cycle in the tissues of other animals. Humans can be infected by both phases.


Most human beings are infected by eating undercooked meat, but exposure to infected cat feces is also a significant hazard, especially for pregnant women. The risk is very low if the research cats have been housed in a rodent-proof facility for a month or more and have been fed only commercial cat food. If there is a chance that feral mice can find their way into the facility, then the risk is much greater. If the cats have been obtained from a random source within the last month, then there is a much greater possibility that their feces may be infectious.


In the research facility, the research facility should be designed so that no rodents have access to the inside of the buildings. Cats should be considered to be at risk if:

  • Evidence of feral rodents are seen around the facility.
  • Cats are fed raw meat.
  • Cats have been obtained within the last 30 days from an outside source.
  • Routine health screens of the cats reveal coccidial oocysts.

Special Note to Women of Childbearing Age

Women who are of childbearing age, or who are contemplating pregnancy, and who work with cats in a research setting should consult with the occupational health physician at Employee Health Services (860-679-2893) and discuss the advisability of having their titer to T. gondii measured as part of their routine prenatal care.