Updated: April 2013. Planned review date: April 2015.
Toxoplasmosis (or toxoplasma infection) is caused by a parasite called Toxoplasma gondii. In non-pregnant women it doesn’t have many symptoms.
In fact, many people will never know they have had it. Some people may have mild flu-like symptoms. A few may experience a more long-term illness similar to glandular fever and swollen lymph nodes. However if you are pregnant and become infected, toxoplasmosis may have serious effects on your baby’s development. It might also cause miscarriage and stillbirth.
How common is toxoplasmosis?
It is estimated that between a third and half of the UK population will have the infection at some point in their lives. Once you have had the infection, you are then immune for life – you cannot catch it again. Around 2,000 UK women per year contract toxoplasmosis during pregnancy.
Most pregnant women may never know they have been infected unless they experience problems during their pregnancy that mean they have tests. However the infection often has no symptoms at all.
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How is toxoplasmosis caught?
If you eat anything infected with the parasite you could catch it. This includes raw and undercooked meat from infected animals (particularly lamb and pork, but also beef and venison), raw cured meat, unwashed fruit and vegetables, unpasteurised goats’ milk and goats’ milk products. It also includes eating anything with infected cat faeces in it (for example, soil left on vegetables). Person-to-person infection is not possible, except from mother to unborn child.
The incubation period is 5–23 days after coming into contact with the parasite. However, toxoplasmosis does not usually have any obvious symptoms and many people do not know they are infected. The only conclusive method of detecting if you have become infected is to have a blood test.
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Who is at risk?
Anyone who eats anything infected with the parasite. Pregnant women who work on the land, in catering or farming may be at higher risk as they may be more likely to come into contact with the parasite. Lambing is a particular risk for pregnant women.
Toxoplasmosis cannot be caught by stroking a cat or having a cat as a pet. The infection comes from coming into contact with the infected faeces of a cat.
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Toxoplasmosis in pregnancy
Toxoplasmosis is a risk to your baby only if you catch it for the first time during pregnancy or within a few weeks before you get pregnant. If an unborn baby catches the disease they are said to have ‘congenital toxoplasmosis’. The damage the infection may cause will depend on when in pregnancy you got the infection.
However, if you do get toxoplasmosis while pregnant, your baby won’t necessarily be infected. On average, only 4 in 10 infections pass on to the baby. If the infection is caught, it can cause miscarriage, stillbirth, brain damage or eye damage.
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What do I do if I think I have toxoplasmosis?
Toxoplasmosis is not routinely tested for during pregnancy in the UK. You may however request a blood test from your GP if you feel you may have put yourself at risk, you are concerned about symptoms or you would like to know if you are immune (ie, if you had the infection at some point in the past).
The blood test looks for antibodies – the body’s natural defences – to the infection. It may take three weeks for these antibodies to be present following an infection, so the blood test will only pick up an infection that you’ve had for at least three weeks. Depending on the type of antibodies found and whether levels are stable, rising or falling, it’s possible to determine when the infection took place.
The results may come back in a week, or longer if they have been passed on to a Toxoplasma Reference Laboratory.
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Effects on the baby
The likelihood of your baby getting toxoplasmosis is higher the further in pregnancy you catch the infection.
There is about 10–15 percent risk of transmitting the disease to your baby. If infection does happen, there is a risk of miscarriage or for the baby to develop hydrocephalus (water on the brain), calcifications on the brain or retinochoroiditis (inflammation of the retina).
There is about a 25 percent risk of transmission. The risk of miscarriage is lower, but the same symptoms as above may be developed.
Risk of transmission to your baby may be as high as 70–80 percent. Most babies infected at this stage will be apparently healthy at birth, but may develop symptoms later in life, usually eye damage.
Tests can be carried out to find out if your baby has developed the infection. However, these won’t show if there is any damage to your baby.
- Amniocentesis: amniotic fluid is removed from the amniotic sac (the sac which surrounds your baby in the womb).
- Cordocentesis: a sample of your baby’s blood is taken from the umbilical cord.
Either of these tests will only be carried out if you have been diagnosed with the infection from a previous blood test.
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Treatment in pregnancy
If you have been diagnosed with a current infection of toxoplasmosis, you may be offered an antibiotic called spiramycin, which reduces the risk of transmission to your baby. Spiramycin doesn’t fight the infection. Therefore it can only limit any damage if the baby is already infected.
If there is concern that the baby may be infected and you are more than 15 weeks pregnant, you may be offered an amniocentesis (see above). If your baby has been infected, you may be given a combination of pyrimethamine and sulphadiazine. These antibiotics are stronger and help limit damage to the baby, but they can’t undo any damage. Spiramycin may cause some nausea or rashes, while pyrimethamine and sulphadiazine can have side effects for mother and baby in terms of red-blood cell production.
At 20 weeks an ultrasound scan may also highlight any obvious physical problems in the baby. Termination of pregnancy is also an option for some women, when an infected baby with severe developmental problems has been confirmed.
All babies born to women with confirmed toxoplasmosis in pregnancy will be monitored closely by paediatricians and receive blood tests during their first year.
Breastfeeding is safe if you have toxoplasmosis, the disease cannot be transmitted this way. You are also passing on extra antibodies to your baby, making their immune system stronger. Breastfeeding is therefore recommended.
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Reducing the risk
• Do not eat rare meat with any pinkness or blood in it. Eating raw or undercooked meat is the most common cause of getting toxoplasmosis.
• Do not eat cured meats, such as Parma ham and salami.
• Wash your hands and all cooking utensils and surfaces after preparing raw meat.
• Wash all fruit and vegetables, including ready-prepared salads, thoroughly to remove all traces of soil.
• Do not eat unpasteurised goats’ milk and products made from it.
• Always wear gloves when gardening. Take care not to put hands or gloves to your mouth and wash your hands and gloves when finished to remove all traces of soil.
• Always wear rubber gloves when handling dirty cat litter. Take care not to put hands or gloves to your mouth and wash your hands and gloves when finished. Better still, get someone else to do this job
• Cover children's sandboxes to prevent cats from using them as litter boxes.
• Take care when visiting farms and wash hands thoroughly after any contact with sheep. Avoid handling newborn lambs.
• Cats are the only animals that can shed the parasite in their faeces. If precautions are taken, cats are not a particular risk to a pregnant woman. Like humans, cats can sometimes become sick when infected, so care for a sick cat should be left to someone else.
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UK government policy on toxoplasmosis screening
The UK National Screening Committee recently reported that screening for toxoplasmosis in pregnancy should not be offered routinely as there is not enough evidence that it would help.
The Committee suggests that getting pregnant women to avoid undercooked or cured meat and communicating the best ways of avoiding infection is a better way of controlling toxoplasmosis than antenatal screening.
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What is Tommy's doing to help?
Tommy's has taken over the work of The Toxoplasmosis Trust, an organisation set up to provide information about toxoplasmosis. You can order copies of our leaflet Toxoplasmosis and pregnancy online at Tommy's shop.
Tommy's also runs a Toxoplasmosis Support Network to enable people affected by toxoplasmosis to contact others who have been through similar experiences. If you are interested in being put in contact with someone in this network or in joining the network yourself, please call the Tommy's PregnancyLine on 0800 0147 800.
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Also in this section
1. Ho-Yen, D.O. and Joss, A.W.L. (eds.) (1992) Human Toxoplasmosis. Oxford: Oxford University Press.
2. Joynson, D.H.M., Wreghitt, T.G. (2001) Toxoplasmosis: A Comprehensive Clinical Guide. Cambridge: Cambridge University Press
3. Hall, S. Ryan, M., and Buxton D. (2001) 'The epidemiology of toxoplasma infection' in Joynson, D.H.M., Wreghitt, T.G., (eds) Toxoplasmosis: A Comprehensive Clinical Guide. Cambridge: Cambridge University Press; pp58-124.
4. Thulliez, P. (2001) 'Maternal and foetal infection' in Joynson, D.H.M., Wreghitt, T.G., (eds) Toxoplasmosis: A Comprehensive Clinical Guide. Cambridge: Cambridge University Press; pp193-213.
5. Health Protection Agency (2012) 'Investigation of Toxoplasma Infection in Pregnancy' in UK Standards for Microbiology Investigations. 5, Issue 2.2 http://www.hpa.org.uk/SMI/pdf (accessed December 2012)
6. Remington, J.S., McLeod, R., Desmonts, G. (2000) 'Toxoplasmosis' in Remington, J,S., Krupp, M.A., Klein, J.O., Infectious Diseases of the Fetus and the Newborn Infant, 5th edition Philadelphia: W.B. Saunders Company; pp.205-346.
7. Desmonts, G. Couvreur, J., Thulliez, P. (1990) 'Congenital Toxoplasmosis: Five cases with mother-to-child transmission of pre-pregnancy infection'. Press Med. 19:pp.1445-49.
8. Alex, W., and Joss, L. (1992) 'Treatment' in Ho-Yen, D.O. and Joss, A.W.L. (eds.) (1992) Human Toxoplasmosis. Oxford: Oxford University Press; pp. 119-143.
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