ICD-11

A disease caused by an infection with the protozoan parasite Toxoplasma gondii. This disease is characterised by fever, lymphadenitis, sore throat, or rash. Transmission is by direct ingestion of contaminated food, indirectly by food or water contaminated with infected cat faeces, or vertical transmission. Confirmation is by detection of antibodies against Toxoplasma gondii, or identification of Toxoplasma gondii in tissue, cerebrospinal fluid, blood, or other body fluids.

Toxoplasmosis is caused by infection with Toxoplasma gondii, an obligate intracellular parasite. The infection produces a wide range of clinical syndromes in humans, land and sea mammals, and various bird species. T gondii infects a large proportion of the world's population but uncommonly causes clinically significant disease. However, certain individuals are at high risk for severe or life-threatening toxoplasmosis. Individuals at risk for toxoplasmosis include fetuses, newborns, and immunologically impaired patients.

In immunodeficient patients, toxoplasmosis most often occurs in persons with defects in T cell–mediated immunity such as those receiving corticosteroids, anti–tumour necrosis factor (TNF) therapies, or cytotoxic drugs and those with hematologic malignancies, organ transplants, or acquired immunodeficiency syndrome (AIDS).

Pulmonary toxoplasmosis in the immunodeficient patient may appear in the form of interstitial pneumonitis, necrotizing pneumonitis, consolidation, pleural effusion, or empyema, or all of these.

AIDS patients with Toxoplasma pneumonia present with cough, dyspnoea, and fever. As toxoplasmosis is generally seen only in advanced HIV infection with CD4 counts below 100, the majority of AIDS patients who develop toxoplasma pneumonia already have had previous HIV-associated opportunistic infections. In solid organ transplant patients, this is most commonly due to transplantation of a toxoplasma-seropositive lung or heart into a seronegative recipient, resulting in primary pulmonary disease. In bone marrow transplant patients, pulmonary toxoplasmosis occurs in 0.28% to 0.45% of patients. Unlike solid organ transplant patients, most of these patients have reactivation, not primary disease.