Toxoplasmosis is a common infection caused by a parasite. This parasite is called Toxoplasma gondii. It develops inside cats and can then infect other animals or humans.
People who have healthy immune systems often have mild or no symptoms. Many adults have had toxoplasmosis without even knowing it. However, people with weaker immune systems are at a much greater risk for serious complications. These complications may include damage to your:
Pregnant woman who develop the infection can pass the infection to their baby. This can cause the baby to develop serious birth defects.
There are several ways humans can become infected with toxoplasma:
Eating Contaminated Food
Toxoplasma cysts may be present in undercooked meat or on fruits and vegetables that have come into contact with contaminated soil or cat feces.
Inhaling Sporulated Cysts (Oocysts) from Contaminated Dirt or Cat Litter
The development of toxoplasma typically begins when a cat eats meat (often rodents) containing infectious toxoplasma cysts. The parasite then multiplies inside of the cat’s intestines. Over the next several weeks, millions of infectious cysts are shed in the cat’s feces through the sporulation process. During sporulation, the cyst walls harden while the cysts enter a dormant, but infectious stage for up to one year.
Acquiring It from an Infected Person
If a pregnant woman is infected, the parasite can cross the placenta and infect the fetus. However, people who have toxoplasmosis are not contagious. This includes young children and babies infected before birth.
Less commonly, you can get it from an organ transplantation or blood transfusion from an infected person. Laboratories screen closely to prevent this.
The frequency of toxoplasmosis varies greatly worldwide. It’s most common in Central America and Central Africa. This is most likely because of the climate in these areas. Humidity affects how long toxoplasma cysts remain infectious.
Local culinary customs also play a role. Areas where meat is served raw or undercooked have higher rates of infection. The use of fresh meat that has not been previously frozen is also associated with a greater risk of infection.
In the United States, an estimated 11 percent of people between ages 6 to 49 have been infected by toxoplasmosis.
Most people who have toxoplasmosis experience few, if any, symptoms. If you develop symptoms, you’ll most likely experience:
- swelling of the lymph nodes in your neck
- low-grade fever
- muscle aches
These symptoms could be caused by other conditions. You should always talk to your doctor if you’re concerned about any symptoms you have developed.
Toxoplasma infection during pregnancy can be serious because the parasite can cross the placenta and infect the baby. An infected baby may suffer damage to the:
The mother is also at increased risk for miscarriage if she has a recent toxoplasmosis infection.
Some babies show signs of infection on an ultrasound. Your doctor may notice abnormalities in the brain and less commonly in the liver. Toxoplasmosis cysts can be found in the baby’s organs after the infection develops. The most serious damage occurs from nervous system infection. This can include damage to the baby's brain and eyes, either in the womb or after birth. It may cause visual impairment or blindness, intellectual disability, and developmental delay.
Toxoplasmosis and HIV
HIV weakens the immune system. This means people who are HIV-positive are more likely to contract other infections. Women who are pregnant and have HIV are at a greater risk of developing toxoplasmosis. They’re also at greater risk of serious problems from the infection.
All pregnant women should be tested for HIV. If you’re pregnant and you test positive for HIV, talk to your doctor about how to prevent toxoplasmosis.
You have several treatment options if you develop toxoplasmosis during pregnancy.
If you suspect you have a new and first toxoplasmosis infection, your amniotic fluid can be tested to confirm. Medication may prevent fetal death or serious neurologic problems, but it’s unclear if it can decrease eye damage. These medications also have their own side effects.
If there’s no evidence of infection in your baby, your doctor may prescribe an antibiotic called spiramycin for the rest of your pregnancy. This can help reduce your baby’s risk of infection.
If your baby is infected, your doctor will probably prescribe a combination of pyrimethamine (Daraprim) and sulfadiazine for the rest of your pregnancy. Your baby will usually take these antibiotics for up to one year after birth.
The most extreme option is termination of pregnancy. This is only suggested if you develop an infection between conception and the 24th week of your pregnancy. It’s typically not recommended since most children have a good prognosis.
The most common ways to become infected with Toxoplasmosis are eating contaminated meat or produce, or inhaling microscopic toxoplasmosis cysts or spores. You can reduce your risk of infection by:
- eating fully cooked meat
- washing raw vegetables and fruit thoroughly
- washing your hands thoroughly after handling raw meat or vegetables
- avoiding travel to developing countries with a high prevalence of toxoplasma, such as South America
- avoiding cat feces
If you have a cat, change the litter box every two days and periodically wash the litter tray with boiling water. Wear gloves and a mask when you change the litter box. Also, keep your pet indoors and do not feed it raw meat.
There are no vaccines for toxoplasmosis and no medications that can be taken to prevent the infection.
If you’re planning a pregnancy, you should practice the preventive measures outlined above. Also, you should see your doctor at least three months before becoming pregnant to discuss your risk factors. Your doctor can perform a blood test to find out if you have had toxoplasmosis before. If so, you’re immune to getting the infection again because your body produces antibodies. If your blood test shows that you have never been infected, you should continue to practice prevention measures and have an additional test as you progress through your pregnancy.