Foodborne Illness: Toxoplasmosis
What is toxoplasmosis?
Toxoplasmosis is infection with the parasite Toxoplasma gondii. Most people who become infected don't have symptoms. This is because the immune system is usually able to fight the disease. Toxoplasmosis is dangerous to a pregnant woman and her fetus.
What causes it?
Toxoplasmosis can result from:
- Accidentally swallowing Toxoplasma gondii eggs from soil or other contaminated surfaces. This can happen by putting your hands to your mouth after gardening, cleaning a cat's litter box, or touching anything that has come into contact with cat feces.
- Eating raw or partly cooked meat, especially pork, lamb, or venison, or touching your hands to your mouth after touching the meat.
If you are pregnant when first infected with Toxoplasma gondii, you can give the infection to your baby.
You may also receive it through an organ transplantation or a transfusion, although this is rare.
What are the symptoms?
Most people with toxoplasmosis don't have symptoms. When symptoms are present, they are often flu-like and may include swollen lymph glands or muscle aches and pains that last for a few days to several weeks.
Severe toxoplasmosis results in damage to the eyes or the brain. Infants who became infected before birth may be born with serious mental or physical problems.
A person with a weakened immune system can develop life-threatening toxoplasmosis.
Severe symptoms vary depending on which part of the body is affected. If the infection is in the:
- Brain (encephalitis), symptoms include seizures, sensory changes, weakness, changes in behaviour or mental state, and problems with movement.
- Eye (chorioretinitis), symptoms include eye pain and gradual vision loss in one or both eyes.
- Lungs (pneumonia), symptoms include fever and chills, breathing problems and a cough that can cause chest wall pain, fatigue, and weakness.
- Heart (myocarditis), symptoms include shortness of breath, chest pain, feeling tired, and palpitations.
How is it diagnosed?
Because there are typically no symptoms, it is hard to know whether you are infected. If you think that you may have toxoplasmosis, talk to your doctor. They may do specific blood tests for toxoplasmosis.
- If you have an impaired immune system, get the blood test for Toxoplasma gondii. If your test is positive, it means that you have been infected at some time in your life. Your doctor can tell you if and when you need to take medicine to prevent the infection from reactivating. If your test is negative, you have not been infected, and you can take precautions to avoid infection.
- If you are planning to become pregnant, consider being tested for Toxoplasma gondii. If the test is positive, it means you have already been infected at some time in your life and you probably don't have to worry about passing the infection to your future baby (discuss this with your doctor). If the test is negative, take precautions to avoid infection.
- If you are pregnant, you and your doctor should discuss your risk of toxoplasmosis. Your doctor may order a blood sample for testing.
How is toxoplasmosis treated?
In an otherwise healthy person who is not pregnant, treatment is not needed. Symptoms will usually go away within a few weeks.
For people who are pregnant or have weakened immune systems, medicines are available to treat toxoplasmosis.
How can you prevent it?
Because toxoplasmosis usually has no symptoms or only mild symptoms, most people don't need to worry about getting it. But if you have a weakened immune system or are pregnant, you should take steps to prevent toxoplasmosis.
- Wear gloves when you garden or do anything outdoors that involves handling soil. Cats may pass the parasite in their feces and often use gardens and sandboxes as litter boxes. Wash your hands well with soap and warm water after outdoor activities, especially before you eat or prepare any food.
- Have someone who is healthy and not pregnant handle raw meat for you. If this is not possible, wear clean disposable gloves when you touch raw meat, and wash cutting boards, sinks, knives, and other utensils that might have touched the raw meat. Wash your hands well with soap and warm water afterwards.
- Cook foods until they are well done. Use a meat thermometer to be sure foods are cooked to a safe temperature. Do not use the colour of the meat (such as when it is no longer "pink") to tell you that it is done.
Cats can spread Toxoplasma gondii in their feces. Don't bring a cat into your house that might have been an outdoor cat or might have been fed raw meat. Avoid handling stray cats and kittens. If you have a cat:
- Help prevent your cat from getting infected with Toxoplasma gondii. Keep the cat indoors, and feed it dry or canned cat food. Cats can become infected by eating or being fed raw or undercooked meat.
- Have someone who is healthy and not pregnant change your cat's litter box. If this is not possible, wear gloves and clean the litter box daily. Wash your hands well with soap and warm water afterwards.
When do cats spread it?
Cats only spread Toxoplasma gondii in their feces for a few weeks after they are first infected with the parasite. They rarely have symptoms when first infected, so most people don't know whether their cat has been exposed to Toxoplasma gondii. Good tests are not available to determine whether your cat is passing Toxoplasma gondii in its feces.
Your veterinarian can answer other questions you may have about your cat and the risk for toxoplasmosis.
Current as of: October 31, 2022
Author: Healthwise Staff
E. Gregory Thompson MD - Internal Medicine
Adam Husney MD - Family Medicine
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