Table 1 Protozoan parasites with a cerebral tropism
Parasite | Lifestyle | CNS pathological features and severity | Clinical outcome |
|---|---|---|---|
Plasmodium falciparum | Obligate / erythrocytes | Acute cerebral malaria (CM): blood flow obstruction; altered BBB in brain parenchyma [40] | Seizures, retinopathy, elevated cranial pressure leading to brainstem alterations and brain swelling, coma and mortality |
Acanthamoeba | Free-living | Acute: severe oedema and haemorrhagic necrosis, severe meningeal irritation and encephalitis; amoebic cysts found in brain [23] | Headache, fever, altered state of consciousness, loss of reflex activity, abnormal speech and motor patterns. Acanthamoeba granulomatous encephalitis fatal in 90% of cases |
Trypanosoma brucei rhodesiense | Free-living / blood, lymph, CSF | Acute: severe complications including leptomengitis, early meningo-encepahlitis and encephalitis | Sleep cycle disturbance, headache, tremors, loss of motor control, fatal if left untreated |
Trypanosoma brucei gambiense | Free-living / blood, lymph, CSF | Chronic: complications that develop more slowly are accompanied by T. B. gambiense | Sleep cycle disturbance, headache, tremors, loss of motor control, fatal if left untreated |
Toxoplasma gondii | Obligate / any nucleated cell | Latent infection characterised by cyst formation in the brain parenchyma [26]. The acute stage is characterised by rapid tachyzoite proliferation in the brain parenchyma. Reactivation of a chronic infection can occur in the immunocompromised [26] | The chronic stage is generally asymptomatic, but the infection can reactivate if the patient becomes immunosuppressed. The acute stage is characterised by headache, epilepsy, hemiparesis, psychosis, cognitive impairment or adynamia |