Species involved:
(1) various Acanthamoeba species
(2) Balamuthia
Sources: widespread in the environment (soil, dust, environmental water, treated water, compost)
Routes of infection:
(1) nasal inhalation (probably through olfactory plate or from sinusitis)
(2) hematogenous from lung or skin
Time course: weeks to months (as opposed to primary amebic meningoencephalitis, which progresses over days)
Risk factors:
(1) malignancy, including Hodgkin's disease
(2) immunodeficiency
(3) diabetes mellitus
(4) renal failure
(5) cirrhosis and/or alcoholism
(6) tuberculosis
(7) advanced HIV disease
(8) drug abuse
(9) steroid treatment or other immunosuppression
(10) cancer chemotherapy and/or radiation therapy
(11) organ transplantation
(12) general debility
Clinical features:
(1) headache
(2) confusion and mental status abnormalities
(3) nausea and vomiting
(4) fever
(5) lethargy
(6) stiff neck
(7) cranial nerve palsies
(8) hemiparesis
(9) seizures
(10) irritability
(11) hallucinations
(12) photophobia
(13) diplopia
(14) gait ataxia
(15) sleep disturbances
(16) Kernig and/or Babinski sign(s)
Lesions in the CNS:
(1) multifocal inflammatory lesions (granulomatous if immunocompetent)
(2) generalized edema
Diagnosis:
(1) brain biopsy
(2) examination of CSF
(3) culture (NNA seeded with E. coli, supplemented PYG, mammalian cell culture)
(4) indirect immunofluorescence
(5) PCR
