Toxoplasmosis in pregnancy
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What is toxoplasmosis?
Toxoplasmosis is an infection that's passed on by cats. It usually causes mild illness, although people who are infected don't always get sick. But if you get toxoplasmosis when you're pregnant, it can cause serious health problems for your baby. Toxoplasmosis can also be a serious illness for anyone with a weak immune system.

Toxoplasmosis is caused by a tiny parasite. Parasites live inside the bodies of other living things. Some parasites can make you sick, a bit like viruses or bacteria.

Toxoplasmosis is an infection that's passed on by cats.
The parasite that causes toxoplasmosis grows in the intestines of cats. It comes out in their feces (stools), mainly into litter boxes and garden soil. From the soil the parasite can spread to grass, water, and fruit and vegetables. Also, it can be picked up by other animals such as sheep, pigs or deer.1

You can get toxoplasmosis if you:1 2

  • Touch your mouth with your hands after gardening, cleaning a cat's litter box, or touching anything that has come into contact with cat feces
  • Eat undercooked meat from infected animals, especially pork, lamb or venison
  • Touch your mouth after handling raw contaminated meat
  • Use kitchen utensils, chopping boards or foods that have been in contact with raw contaminated meat
  • Eat unwashed fruit or vegetables from contaminated soil
  • Drink contaminated water
  • Receive an infected organ transplant or blood transfusion (although this is rare).
Once you've had toxoplasmosis, you are usually immune for life. This means you don't get it again.

Toxoplasmosis and pregnancy
Toxoplasmosis is usually harmless and goes away on its own.3 But if you pick up toxoplasmosis when you're pregnant, the infection can cause serious health problems for your unborn baby.2 That's because the baby's immune system hasn't developed enough to fight off the infection. So it can spread and cause serious problems.

If you've had toxoplasmosis in the past, before becoming pregnant, it's highly unlikely to affect your baby.1 2 But if you have it during pregnancy, or in the three months before you conceive, the infection can pass to your baby through the placenta (the organ that passes food and oxygen to your unborn baby).4

What's the risk of the infection being passed to my baby?
If you get toxoplasmosis for the first time during pregnancy, it doesn't always mean your baby will get infected. Some research has found that more than half of pregnant women infected with toxoplasmosis for the first time don't pass the infection to their babies.5

The risk of passing on toxoplasmosis to your baby depends on at what point in your pregnancy you became infected. The risk is:

  • Lowest if you get infected in early pregnancy
  • Highest if you get infected in late pregnancy.
For example, the risk of your baby getting infected is just 2 in 100 if you get toxoplasmosis at eight weeks of pregnancy. But this risk rises to 80 in 100 if you become infected with toxoplasmosis shortly before giving birth.6

Babies infected in early pregnancy are more likely to have serious health problems that those infected later. Also, in early pregnancy you may miscarry (lose your baby).

Researchers have found that the most dangerous time for you to catch toxoplasmosis is at 24 weeks to 30 weeks of pregnancy, when there is a 1 in 10 chance of your baby being severely affected.6

How can I protect myself against toxoplasmosis in pregnancy?
If you're pregnant, it's really important to avoid getting toxoplasmosis.3

  • If you have a cat, avoid changing its litter if possible. Have another family member do it. Or if you have to do it yourself, use gloves and then wash your hands thoroughly.
  • See that the litter box is changed daily. It takes the cat feces several days to become infectious.
  • Ideally keep your cat inside, so it can't come into contact with the parasite that causes toxoplasmosis. Or have someone else look after it while you're pregnant. Don't feed it raw or undercooked meat.
  • Don't handle or adopt stray cats.
You can also get toxoplasmosis from contaminated food or directly from contaminated soil. So it's important to:

  • Avoid eating raw or undercooked meat or poultry. Cook meat to safe temperatures, using a thermometer to make sure it is cooked all the way through
  • Peel or wash fruit and vegetables before eating
  • Wash your hands and all utensils, chopping boards, plates, dishes, and counters that have been in contact with raw meat, poultry, seafood, or unwashed fruit and vegetables
  • Wear gloves when gardening and during contact with soil or sand. Afterward wash your hands thoroughly.
How are babies affected by toxoplasmosis?
A baby who gets toxoplasmosis in the womb is said to have congenital toxoplasmosis. Most babies with this infection seem normal at birth. But they can get health problems months, or even years, later. These include:7

  • Eye infections
  • Hearing problems
  • Learning difficulties.
Babies who are badly affected by toxoplasmosis are at risk of:

  • Blindness
  • Deafness
  • Seizures (fits)
  • Brain damage.
Some badly-affected babies are stillborn or die a few days after birth.

Babies with congenital toxoplasmosis are usually treated with antibiotics for about a year after they're born.

Other people at risk
Apart from pregnant women, toxoplasmosis can be serious for people whose immune system has been weakened by:

  • HIV or AIDS
  • Cancer treatment
  • Drugs given after organ transplantation.
Your immune system is the part of your body that usually helps protect you against infection.

People with weak immune systems get a more severe form of the illness, which can be life-threatening. The illness can cause them to have symptoms such as:

  • Seizures
  • Confusion and other mental problems
  • Being partly paralyzed
  • Speech difficulties.
They can also get serious problems in their eyes, lungs, and other organs.

If you are pregnant and you have a weakened immune system, you will need special care during your pregnancy.



Sources for the information on this page:
  1. Jones J, Lopez A, Wilson M. Congenital toxoplasmosis. American Family Physician. 2003; 67: 2131-2138. 12776962
  2. Centers for Disease Control and Prevention. Fact sheet: toxoplasmosis. January 2008. Available at http://www.cdc.gov/toxoplasmosis (accessed on 3 April 2008).
  3. Centers for Disease Control and Prevention. Preventing congenital toxoplasmosis. March 2004. Available at http://www.cdc.gov (accessed on 3 April 2008).
  4. Montoya JG, Liesenfeld O. Toxoplasmosis. Lancet. 2004; 363: 1965-1976. 15194258
  5. National Collaborating Centre for Women and Children's Health. Antenatal care: routine care for the healthy pregnant woman. October 2003. NICE clinical guideline 6. Available at http://www.nice.org.uk/cg006 (accessed on 4 April 2008).
  6. Dunn D, Wallon M, Peyron F, et al. Mother-to-child transmission of toxoplasmosis: risk estimates for clinical counselling. Lancet. 1999; 353: 1829-1833. 10359407
  7. National Toxicology Program: Center for the Evaluation of Risks to Human Reproduction. Toxoplasmosis. September 2006. Available at http://cerhr.niehs.nih.gov (accessed on 3 April 2008).
This information was last updated in Apr 21, 2008