The National Academies

The National Academies: What You Need To Know About Infectious Disease

What You Need To Know About Infectious Disease


Toxoplasmosis is a disease caused by a parasite called Toxoplasma gondii. Eating undercooked, contaminated meat; drinking water that contains the parasite; and contact with cat feces—by cleaning a litter box, for example—are the most common ways to become infected with the parasite. More than 60 million people carry the parasite in their intestines, but as long as their immune systems are healthy, it does not cause any problems. Pregnant women and people with compromised immune systems, however, are at risk for serious health problems. Pregnant women can transmit the parasite to their fetuses, potentially causing health issues for their babies later in life.

Many people infected with Toxoplasma gondii have no symptoms. Others may have flu-like symptoms, including swollen lymph nodes and muscle aches that may last for more than a month. If the parasite infects the eye, symptoms can range from blurred or reduced vision to redness and tearing. Severe cases of the disease can lead to damage to the eyes, brain, or other organs. Such cases can be the result of an acute episode or a reactivation of an infection that occurred at an earlier time. Individuals with compromised immune systems are at a higher risk for a severe case of toxoplasmosis.

Diagnosis of the infection is confirmed by a blood test. At that point, individuals should discuss their treatment options with their physician. For otherwise healthy people, no treatment may be needed. Symptoms usually go away within a few weeks or months. For pregnant women or individuals with compromised immune systems, medications, such as pyrimethamine and sulfadiazine, plus folinic acid, can be used.

Many simple measures can be taken to avoid toxoplasmosis. Cook all meat thoroughly. Freezing meat before cooking also ensures that the meat is parasite free. Wash all fruits and vegetables carefully, as well as cutting boards and utensils. Encourage all family members to wash their hands multiple times during the day, but especially before eating. When gardening or changing the cat’s litter box, consider wearing gloves to avoid contact with the parasite.


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What do you know about infectious disease?

Which are larger?

  • Correct!

    Bacteria are 10 to 100 times larger than viruses.

  • Sorry, that’s incorrect.

    Bacteria are 10 to 100 times larger than viruses.

Infectious Disease Defined


The relative occurrence of a disease or a condition that causes illness.

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