In most cases, toxoplasmosis doesn't cause any symptoms and the person isn't aware they're infected.
This is because the immune system is normally strong enough to fight the infection and stop it causing serious illness.
However, some people will develop flu-like symptoms. There's also a risk of more serious problems if a woman becomes infected while she's pregnant, or if someone with a weak immune system becomes infected.
About 10-20% of people infected with toxoplasmosis will develop symptoms similar to flu or glandular fever, such as:
These symptoms are usually mild and will normally pass within a few weeks.
Problems in pregnancy
Toxoplasmosis can be serious if a woman becomes infected while she's pregnant or a few weeks before conceiving. This is because there's a chance the infection could be passed to her baby.
However, the risk of getting toxoplasmosis during pregnancy is very low. In the UK, it's estimated that less than 5 in every 1,000 pregnant women will become infected for the first time.
A woman won't usually have any symptoms if she becomes infected during pregnancy, but if the infection spreads to her baby, it can cause:
- congenital toxoplasmosis – where the baby develops toxoplasmosis while they're developing in the womb
Congenital toxoplasmosis can cause serious problems that are either noticeable from birth or develop several months or years later, such as brain damage, hearing loss and vision problems.
Problems in people with weak immune systems
Toxoplasmosis can cause serious problems and be life-threatening for someone with a weakened immune system as their body may not be able to fight off the infection.
Your immune system may be weakened if you:
- have an illness that affects your immune system, such as HIV and AIDS or some types of cancer
- are having chemotherapy
- are taking immunosuppressant medication – for example, after having an organ transplant
If your immune system is weak, the infection could spread to organs such as the eyes, heart, lungs and brain. This can cause problems such as headaches, confusion, poor co-ordination, seizures (fits), difficulty breathing and vision problems.
Read about the complications of toxoplasmosis for more information.