Granulomatous amoebic encephalitis (GAE)
Acanthamoeba GAE is an insidious, multifocal, slowly progressive infection which spans from several weeks to months. This long incubation period makes the portal of entry difficult to establish, but inhalation of the amoeba through the nasal passages and lungs or introduction through skin lesions are the most likely routes of infection. Primarily affected are individuals with compromised immune systems, and while very uncommon, healthy individuals have also been known to become infected. GAE typically presents as an inflammation of the lungs, sinuses, or skin infections with the potential to spread to the brain. Common early symptoms may include headache, altered mental status, hemiparesis, and fever. Nausea and vomiting may also be an early symptom. There is limited information concerning the pathogenesis of the infection or the human host response to the infection. It is felt that the course of infection is the result of different mechanisms. Much of the damage is done by the trophozoites through phagocytosis which destroys the host’s cells and by the secretion of enzymes which facilitates the invasion of the amoebae and provides nutrients by lysis of the host’s cells. Mortality of GAE is high, reaching almost 100% if the patient presents with both skin lesions and CNS involvement.