Treatment training manual

5.11 Toxoplasmosis

Type of infection

Toxoplasmosis (toxo) is an illness caused by a protozoa.

Toxo is mainly transmitted by eating raw or under-cooked meat, or through exposure to cat faeces that is more than 1 day old.

Many adults have been exposed to toxo. But there is usually a risk of illness only when CD4 levels are below 200 cells/mm3.

If untreated, toxo can be fatal.

Main symptoms

Toxo usually affects the brain (toxoplasma encephalitis). Symptoms include:

  • Fever.
  • Headache.
  • Disorientation, confusion.
  • Memory loss.
  • Vision loss.
  • Behaviour change.

Toxo can affect organs, including the eyes and lungs.


Diagnosis is difficult. Blood tests for antibodies, and even viral load tests in CSF (cerebrospinal fluid) are not always positive. Brain scans can highlight any damage to the brain, but rarely provide enough information to diagnose the cause of the damage.

Symptoms are often sufficient to start treatment. If symptoms improve within 2 weeks then toxoplasmosis will have been the cause. A brain scan will show reduced damage within 3 weeks.


  • Treatment with the antibiotics pyrimethamine plus sulphadiazine is effective and usually straight forward.
  • If there is a bad reaction to sulphadiazine, then clindamycin, clarithromycin or azithromycin can be used but they are not as effective.

After a successful response to treatment (usually three weeks) maintenance therapy is continued with low dose pyrimethamine plus either sulphadiazine or clindamycin.

Treatment is life-long while CD4 count remains below 200.

Treatment can be safely stopped sometimes if ARVs brings the CD4 count over 200. This also depends on the severity of the previous illness.


Prophylaxis is used in people with CD4 counts under 200.

  • The first option is co-trimoxazole (Septrin, Bactrim, TMP-SMX) – Co-trimoxazole is made up of two drugs trimethoprim (TMP) and sulphamethoxazole (SMX).
  • For people who can not tolerate co-trimoxazole, either atovaquone or dapsone are options. Sometimes these are used with pyrimethamine.

The drugs used to protect against toxo also protect against PCP.


Alternative antibiotics like azithromycin and doxycycline are being looked at.

Last updated: 1 January 2016.