What is toxoplasmosis?
A single-celled parasite called Toxoplasma gondii causes a disease known as toxoplasmosis. While the parasite is found throughout the world, more than 60 million people in the United States may be infected with the Toxoplasma parasite. Of those who are infected, very few have symptoms because a healthy person’s immune system usually keeps the parasite from causing illness. However, pregnant women and individuals who have compromised immune systems should be cautious; for them, a Toxoplasma infection could cause serious health problems.
How do people get toxoplasmosis?
A Toxoplasma infection occurs by:
- Eating undercooked, contaminated meat (especially pork, lamb, and venison).
- Accidental ingestion of undercooked, contaminated meat after handling it and not washing hands thoroughly (Toxoplasma cannot be absorbed through intact skin).
- Eating food that was contaminated by knives, utensils, cutting boards and other foods that have had contact with raw, contaminated meat.
- Drinking water contaminated with Toxoplasma gondii.
- Accidentally swallowing the parasite through contact with cat feces that contain Toxoplasma. This might happen by
- cleaning a cat’s litter box when the cat has shed Toxoplasma in its feces
- touching or ingesting anything that has come into contact with cat feces that contain Toxoplasma
- accidentally ingesting contaminated soil (e.g., not washing hands after gardening or eating unwashed fruits or vegetables from a garden)
- Mother-to-child (congenital) transmission.
- Receiving an infected organ transplant or infected blood via transfusion, though this is rare.
Symptoms of the infection vary.
- Most people who become infected with Toxoplasma gondii are not aware of it.
- Some people who have toxoplasmosis may feel as if they have the “flu” with swollen lymph glands or muscle aches and pains that last for a month or more.
- Severe toxoplasmosis, causing damage to the brain, eyes, or other organs, can develop from an acute Toxoplasmainfection or one that had occurred earlier in life and is now reactivated. Severe cases are more likely in individuals who have weak immune systems, though occasionally, even persons with healthy immune systems may experience eye damage from toxoplasmosis.
- Signs and symptoms of ocular toxoplasmosis can include reduced vision, blurred vision, pain (often with bright light), redness of the eye, and sometimes tearing. Ophthalmologists sometimes prescribe medicine to treat active disease. Whether or not medication is recommended depends on the size of the eye lesion, the location, and the characteristics of the lesion (acute active, versus chronic not progressing). An ophthalmologist will provide the best care for ocular toxoplasmosis.
- Most infants who are infected while still in the womb have no symptoms at birth, but they may develop symptoms later in life. A small percentage of infected newborns have serious eye or brain damage at birth.
People who are most likely to develop severe toxoplasmosis include:
- Infants born to mothers who are newly infected with Toxoplasma gondii during or just before pregnancy.
- Persons with severely weakened immune systems, such as individuals with AIDS, those taking certain types of chemotherapy, and those who have recently received an organ transplant.
If you are planning to become pregnant, your health care provider may test you for Toxoplasma gondii. If the test is positive it means you have already been infected sometime in your life. There usually is little need to worry about passing the infection to your baby. If the test is negative, take necessary precautions to avoid infection (See below).
If you are already pregnant, you and your health care provider should discuss your risk for toxoplasmosis. Your health care provider may order a blood sample for testing.
If you have a weakened immune system, ask your doctor about having your blood tested for Toxoplasma. If your test is positive, your doctor can tell you if and when you need to take medicine to prevent the infection from reactivating. If your test is negative, it means you need to take precautions to avoid infection. (See below).
If you suspect that you may have toxoplasmosis, talk to your health care provider. Your provider may order one or more varieties of blood tests specific for toxoplasmosis. The results from the different tests can help your provider determine if you have a Toxoplasma gondii infection and whether it is a recent (acute) infection.
Once a diagnosis of toxoplasmosis is confirmed, you and your health care provider can discuss whether treatment is necessary. In an otherwise healthy person who is not pregnant, treatment usually is not needed. If symptoms occur, they typically go away within a few weeks to months. For pregnant women or persons who have weakened immune systems, medications are available to treat toxoplasmosis.
There are several general sanitation and food safety steps you can take to reduce your chances of becoming infected with Toxoplasma gondii.
Cook food to safe temperatures. A food thermometer should be used to measure the internal temperature of cooked meat. Do not sample meat until it is cooked. USDA recommends the following for meat preparation.
For Whole Cuts of Meat (excluding poultry)
Cook to at least 145° F (63° C) as measured with a food thermometer placed in the thickest part of the meat, then allow the meat to rest* for three minutes before carving or consuming.
For Ground Meat (excluding poultry)
Cook to at least 160° F (71° C); ground meats do not require a rest* time.
For All Poultry (whole cuts and ground)
Cook to at least 165° F (74° C), and for whole poultry allow the meat to rest* for three minutes before carving or consuming.
*According to USDA, “A ‘rest time’ is the amount of time the product remains at the final temperature, after it has been removed from a grill, oven, or other heat source. During the three minutes after meat is removed from the heat source, its temperature remains constant or continues to rise, which destroys pathogens.”
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- Freeze meat for several days at sub-zero (0° F) temperatures before cooking to greatly reduce chance of infection.
- Peel or wash fruits and vegetables thoroughly before eating.
- Do not eat raw or undercooked oysters, mussels, or clams (these may be contaminated with Toxoplasma that has washed into sea water).
- Do not drink unpasteurized goat’s milk.
- Wash cutting boards, dishes, counters, utensils, and hands with hot soapy water after contact with raw meat, poultry, seafood, or unwashed fruits or vegetables.
- Wear gloves when gardening and during any contact with soil or sand because it might be contaminated with cat feces that contain Toxoplasma. Wash hands with soap and warm water after gardening or contact with soil or sand.
- Teach children the importance of washing hands to prevent infection.
Yes, you may keep your cat if you are a person at risk for a severe infection (e.g., you have a weakened immune system or are pregnant); however, there are several safety precautions to avoid being exposed to Toxoplasma gondii :
- Ensure the cat litter box is changed daily. The Toxoplasma parasite does not become infectious until 1 to 5 days after it is shed in a cat’s feces.
- If you are pregnant or immunocompromised:
- Avoid changing cat litter if possible. If no one else can perform the task, wear disposable gloves and wash your hands with soap and warm water afterwards.
- Keep cats indoors.
- Do not adopt or handle stray cats, especially kittens. Do not get a new cat while you are pregnant.
- Feed cats only canned or dried commercial food or well-cooked table food, not raw or undercooked meats.
- Keep your outdoor sandboxes covered.
Your veterinarian can answer any other questions you may have regarding your cat and risk for toxoplasmosis.
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No, cats only spread Toxoplasma in their feces for a few weeks following infection with the parasite. Like humans, cats rarely have symptoms when infected, so most people do not know if their cat has been infected. The Toxoplasma shedding in feces will go away on its own; therefore it does not help to have your cat or your cat’s feces tested for Toxoplasma.
From the Center for Disease Control and Prevention (CDC)