TABLE 2.

Differences among the free-living amebae causing disease in humans^a

Characteristic	Acanthamoeba			Balamuthia	Naegleria
	GAE	AK	Cutaneous lesions, sinusitis	GAE	PAME
Portal of entry	Olfactory epithelium, respiratory tract, skin, sinuses	Corneal abrasion	Skin, sinuses, respiratory tract	Olfactory epithelium, skin, respiratory tract	Olfactory epithelium
Incubation Period	Weeks to months	Days	Weeks to months	Weeks to months	Days
Clinical signs	Confusion, headache, stiff neck, irritability	Blurred vision, photophobia, inflammation, corneal ring	Skin lesions, nodules, sinus lesions, sinusitis	Slurred speech, muscle weakness, headache, nausea, seizures	Headache, nausea, vomiting, confusion, fever, stiff neck
Pathology	Focal necrosis, granulomas	Ulceration of cornea	Granulomatous reaction in skin, inflammation	Multiple necrotic foci, inflammation, cerebral edema	Hemorrhagic necrosis
Diagnosis	Brain biopsy, CSF smear/wet prep, culture, IIFb of tissue, PCR	Corneal scrape, corneal biopsy, calcofluor white, culture of material, confocal microscopy	Skin lesion biopsy, culture, IIF of tissue	Brain biopsy, culture on mammalian cells, IIF of tissue	Brain biopsy, CSF wet prep, CSF culture, IIF of tissue, PCR

^aData from references 113, 286, and 387.

^bIIF, indirect immunofluorescence.