Toxoplasmosis Frequently Asked Questions
What is Toxoplasmosis?
Toxoplasmosis is a disease caused by a common parasite called Toxoplasma gondii, which can infect all mammals and birds and is found throughout the world. Up to one billion of the world's human population has become infected with Toxoplasma. Toxoplasmosis is a notifiable disease in Ireland.
In Ireland toxoplasmosis is reported relatively rarely. However, as symptoms in healthy people are generally mild and non-specific, a significant proportion of cases probably go unnoticed. Studies in the UK have estimated that between 7-34% of people have been infected with T. gondii. In an Irish study, around 13% of children were shown to have been infected. However, the vast majority of these people will not have noticed any symptoms.
Who is at risk of developing severe disease?
Most healthy people who become infected do not experience any symptoms, however about 10% develop a mild flu-like illness. The parasite can form microscopic cysts in muscle tissue, and remain in the body for many years. These cysts do not pose any risk to people with healthy immune systems.
People with living with HIV/AIDS, or taking anticancer therapy, or recent transplant recipients may be at greater risk of developing disease
Babies born to mothers who became infected with Toxoplasma during or just before they became pregnant are also at greater risk of severe toxoplasmosis, as the mother can pass the parasite to the child in the womb.
Toxoplasmosis of the eye (ocular toxoplasmosis) can sometimes develop, particularly in unborn babies of infected mothers and people with immune deficiency. Symptoms include blurred vision, and 'floaters' (dark spots that pass across your field of vision).
Toxoplasmosis in pregnancy
If a woman becomes infected with toxoplasma for the first time while she is pregnant, although she may not experience any symptoms, the infection can be passed on to her unborn child and may lead to congenital toxoplasmosis. How severe congenital toxoplasmosis is depends on the stage of pregnancy at which the mother is infected.
Most children born with congenital toxoplasmosis have no symptoms early on, but a large percentage will show signs of infection months to years later. A few may show signs of infection at birth or within the first month of life. Some babies can be born prematurely or are unusually small at birth. Other signs and symptoms, if there are any at all, may include:
- swollen glands
- enlarged liver or spleen
- large or small head circumference
- easy bruising
Occasionally the brain and nervous system can be affected leading to:
- feeding difficulties
- mental retardation
It is rare for a mother to become infected early in the pregnancy, however if this occurs the effect on the foetus may be severe, and lead to complications such as miscarriage, stillbirth or birth defects. Babies whose mothers are infected during the last 28 weeks of pregnancy very rarely experience any problems or symptoms at birth. Complications of the infection may however develop much later, when they are in their 20s or 30s.
A pilot national congenital toxoplasmosis screening programme was conducted in Ireland for two years from July 1st 2005. Under this programme, babies were screened for congenital toxoplasmosis (unless a parent specifically refused testing) at the National Newborn Screening Laboratory when testing for five other disorders was undertaken using the 'heel prick test'.
Further information is available in the Toxoplasmosis and Pregnancy Information Leaflet
Toxoplasmosis in the immunocompromised
People who have weakened immune systems, such as individuals who are living with HIV, patients who have undergone organ transplantation, or those taking certain types of anticancer therapy are at greater risk of developing severe toxoplasmosis (see above). Symptoms include headaches, confusion, seizures, chest pains, coughing up blood and breathing difficulties. The disease can be fatal in some cases. There is also a risk of developing permanent eye or brain damage, such as encephalitis.
How do people get toxoplasmosis?
The parasite that causes toxoplasmosis can be found in the faeces of infected cats, and in the meat of infected animals. Cats are the only species in which Toxoplasma gondii can multiply and it does this in the cat's gut. From there it is shed in cat faeces as minute eggs (oocysts). Once cats have been infected they can spread the parasite in their faeces for a few weeks. Cats do not usually show symptoms when they are first infected, so people may not know if their cat has been infected. Sheep can also be infected, and Toxoplasma is one of the main causes of abortion in ewes.
Humans can be infected with Toxoplasma by five major routes:
- Swallowing water, food or soil contaminated with the faeces of infected cats
- From a newly infected mother to her unborn baby
- Swallowing or handling undercooked or raw meat (mainly pork or lamb) that contains the tissue cyst form of the parasite
- Handling an infected lambing ewe, the afterbirth, or their newborn lamb
- Receiving organ transplants or blood products from donors with toxoplasmosis, although this is rare
Children and adults do not transmit toxoplasmosis to one another.
What is the treatment for toxoplasmosis?
In healthy individuals treatment for toxoplasmosis is not usually needed. A range of anti-toxoplasma drug treatments are available for those at greater risk of severe toxoplasmosis.
How can I prevent toxoplasmosis?
The main way to prevent Toxoplasma infection is to take general precautions to avoid ingesting the parasite.
For pregnant women and people in other 'at risk' groups,
- Cook your meat completely (no pink should be seen and the juices should be clear). Do not eat undercooked or rare meats.
- Wash your hands with soap and water after any exposure to soil, sand, raw meat, or unwashed vegetables.
- Do not sample meat until it is cooked.
- Wash all cutting boards, utensils and surfaces thoroughly with hot soapy water after each use, and especially after contact with raw meat.
- Wash and/or peel all fruits and vegetables before eating them.
- Avoid unpasteurised goats milk
- Limit your exposure to cat litter and soil contaminated with cat faeces
- Cover children's outdoor sandboxes to prevent cats from using them as litter boxes.
- Wear gloves when gardening or handling sand from a sandbox. Wash hands well afterward.
- Try to limit your contact with stray cats, especially kittens.
- Avoid contact with sheep at lambing time
- Avoid handling dirty clothing used by those handling lambing ewes and newborn lambs
I own a cat. Do I have to give up my cat while pregnant or if I am in another 'at risk' group?
If you own a cat, there is no need to give up your cat while pregnant, if you are planning to become pregnant or if you are in another 'at risk' group, but the following extra precautions can help reduce your risk of exposure to Toxoplasma:
- Provide a litter tray for your cat to minimise utilisation of areas such as garden soil and sandpits
- It is advisable to change the litter tray daily because the parasite does not become infectious until 1 to 5 days after it is shed in cat faeces.
- If possible, have someone else change your cats litter box. If you have to change it, wear disposable gloves and wash your hands thoroughly with soap and water afterwards.
- Feed your cat commercial dry or canned food. Don't feed cats raw meat because this can be a source of Toxoplasma infection.
- During your pregnancy try and keep your cat indoors and away from dead animals and birds.
- Prevent cats hunting birds and other prey, e.g. by use of a bell collar.
- Do not get a new cat while you are pregnant.
Based on CDC, HPA, HSE-SE and HSE-M leaflets
This factsheet is also available in Polish.
Last reviewed: March 2023