Cerebral toxoplasmosis (toxoplasma infection of the brain): symptoms and treatment

Toxoplasmosis is an infection caused by the parasite Toxoplasma gondii. The NHS says it is a common infection that you can catch from the poo of infected cats, or infected meat, and that it is usually harmless. UKHSA describes it as an infection that can pass from mammals to humans.

Toxoplasma infection of the central nervous system, which is the brain and spinal cord, is the form that affects people whose immune defences are weak. The NHS notes that if you have a weakened immune system toxoplasmosis may cause problems with your eyes, brain, heart or lungs. The brain infection is sometimes called toxoplasma encephalitis or cerebral toxoplasmosis.

UKHSA says that those at most risk are pregnant women, who can pass congenital toxoplasmosis to their unborn babies, and people with weakened immune systems. The NHS gives examples of a weakened immune system as having HIV, taking immunosuppressant medicines or having chemotherapy.

The NHS HIV page explains that HIV weakens the immune system and, if not treated, may eventually cause more serious illnesses, known as advanced HIV, late-stage HIV or AIDS, but that in the UK most people being treated for HIV do not develop AIDS. Brain infection with toxoplasma is therefore mainly a concern for people with untreated or late-diagnosed HIV, or those on strong immunosuppression after a transplant or for cancer or autoimmune disease.

The NHS says most people with toxoplasmosis have no symptoms, though some have flu-like symptoms such as a high temperature, headache, sore throat, aching body, swollen glands and tiredness. More serious symptoms are confusion, blurred vision, slurred speech and unsteady walking.

The NHS encephalitis page, describing brain inflammation more generally, lists confusion or disorientation, seizures, changes in personality and behaviour, difficulty speaking, weakness or loss of movement in parts of the body and loss of consciousness as serious symptoms for which you should dial 999 immediately. A person with a weakened immune system who develops a new headache, fever, confusion, fits, weakness or speech or vision change should be assessed urgently.

• New or worsening headache with fever.

• Confusion, drowsiness or personality change.

• Seizures or fits.

• Weakness or loss of feeling on one side, or unsteady walking.

• Slurred speech or blurred vision.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you are pregnant or have a weakened immune system and have any symptoms of toxoplasmosis, if you have blurred vision or if you have difficulty walking. It says to go to A&E or call 999 if you or someone else suddenly gets confused or has slurred speech, and not to drive yourself to A&E.

The NHS says a GP may do blood tests to see if you have been infected with toxoplasmosis and can prescribe medicines to treat the infection if necessary. UKHSA explains that Public Health England, in collaboration with Public Health Wales, reviews cases of infection diagnosed each quarter by the Toxoplasma reference laboratory in Swansea, and that laboratories can contact the reference laboratory for information about tests.

Where brain infection is suspected in someone with a weakened immune system, the hospital team will look for the underlying immune problem. The NHS HIV page says that an HIV test can be arranged through a GP or sexual health clinic, and the NHS says encephalitis-type illnesses need to be treated in hospital.

The NHS says that most people who get toxoplasmosis get better without treatment, but that you will usually be given medicines, including antibiotics, if you are pregnant, have a weakened immune system such as HIV or immunosuppressant medicines, or have symptoms affecting the eyes. It adds that if you are seriously ill you may need to be treated in hospital.

For the brain infection the treating specialist chooses the medicines and how long they are given. Where HIV is the cause, starting or optimising HIV treatment is a key part of care, because the NHS says that with treatment most people with HIV can live a long and healthy life.

The NHS says the parasite can be found in the poo of infected cats, in undercooked meat and in soil contaminated by cat poo. If you are pregnant or have a weakened immune system it advises wearing gloves for gardening and washing hands afterwards, washing hands before preparing food and eating, washing hands, knives and chopping boards after preparing raw meat, washing fruit and vegetables thoroughly, cooking meat thoroughly, especially lamb, pork and venison, and avoiding cat poo in litter and soil, wearing gloves if you must empty litter trays.

It says not to eat raw or undercooked meat or cured meats like salami or parma ham, not to have unpasteurised goats' milk, not to touch pregnant sheep or lambs and not to feed cats raw meat. It also says you cannot catch toxoplasmosis from stroking a cat or having a cat as a pet. UKHSA's case-control study found a strong association with beef, which emphasises thorough cooking and hygienic food handling for vulnerable groups.

Cerebral toxoplasmosis is managed in hospital by infectious diseases, HIV or neurology specialists, with emergency admission usually needed. HIV care in the NHS is provided free through sexual health and HIV clinics. Private care generally follows the same specialist principles but is not usually the first route for an acute neurological illness.