A Sexually Active 23-Year-Old With Seizures and Tongue Pain

Manuel Salinas, MD


October 05, 2021


The noncontrast CT scan revealed large, hypodense lesions located in the right frontal cerebral hemisphere, bilateral thalami, and basal ganglia extending into the centrum semiovale, with mild compression of the right lateral ventricle. Subsequent administration of contrast resulted in enhancement of the peripheral zone of the lesions in a typical ring pattern, suggesting CNS toxoplasmosis (images not available).

Toxoplasmosis is caused by the protozoan Toxoplasma gondii.[1,2] The organism is a ubiquitous coccidian parasite that infects more than 50% of individuals in some populations but does not commonly cause active disease. It has the following three forms:

  • Oocysts, which are excreted in cat feces (the definitive host)

  • Tachyzoites, which multiply intracellularly

  • Tissue cysts, the end product of this intracellular multiplication, which can persist as viable parasites in the brain and striated muscles throughout the life of the host

Toxoplasmosis infection usually occurs via the ingestion of oocysts or tissue cysts. The infection has four stages: acute, subacute, chronic, and reactivation. After the organisms invade and multiply within the GI tract, they spread through the lymphatic system and the bloodstream to distant organs (acute stage). Cellular and humoral immune responses then suppress disease progression and limit the parasite burden in organs. In immunocompetent hosts, the parasite encysts and persists without any inflammatory process (chronic stage). When the host becomes immunocompromised, bradyzoites are released and the parasite becomes an opportunistic agent causing disease.

CNS manifestations are the most frequent form of disease and occur in 10%-25% of individuals with AIDS. The affinity of T gondii for brain tissue has been conferred to low local immunity. These manifestations are initially protean and may develop insidiously. Focal neurologic signs may arise, accompanied by generalized cerebral dysfunction (drowsiness progressing into coma). Seizures may be present and may be generalized or focal. Hemianopia, aphasia, ataxia, and cranial nerve palsies may also be observed. Low-grade fever and progressive headaches are frequent symptoms. The clinical signs of CNS toxoplasmosis are typically vague and vary among patients; thus, confirming the diagnosis with radiologic and serologic studies is important.[1.2]


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