Severe toxoplasmosis

When newly infected with toxoplasmosis, most people either at first feel like they have the flu or do not feel sick at all. This is why people rarely know whether or when they've had toxoplasmosis.

A person with an immune system weakened by HIV infection, organ transplant medicines, or lymphoma can develop life-threatening toxoplasmosis. Antibiotic therapy is often used to prevent this from happening, and severe infection requires aggressive treatment.

Severe symptoms vary depending on which part of the body is affected. If the infection is in the:

  • Brain (encephalitis), symptoms include seizures, sensory changes, weakness, changes in behavior or mental state, and problems with movement.
  • Eye (chorioretinitis), symptoms include eye pain and gradual vision loss in one or both eyes.
  • Lungs (pneumonia), symptoms include fever and chills, breathing problems and a cough that can cause chest wall pain, fatigue, and weakness.
  • Heart (myocarditis), symptoms include irregular heartbeat, signs of pericarditis, and signs of heart failure.

On rare occasions, seemingly healthy people have been known to develop serious symptoms of toxoplasmosis.1


  1. Montoya JG, et al. (2005). Toxoplasma gondii section of Infectious diseases and their etiologic agents. In GL Mandell et al., eds., Principles and Practice of Infectious Diseases, pp. 3170–3198. Philadelphia: Elsevier Churchill Livingstone.

Last Updated: February 23, 2009

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