,
trophozoites
, and
flagellated forms
, in its
life cycle. The trophozoites replicate by promitosis (nuclear membrane
remains intact)
.
Naegleria fowleri is found in fresh water, soil, thermal discharges of
power plants, heated swimming pools, hydrotherapy and medicinal pools,
aquariums, and sewage. Trophozoites can turn into temporary flagellated
forms which usually revert back to the trophozoite stage. Trophozoites
infect humans or animals by entering the olfactory neuroepithelium
and
reaching the brain. N. fowleri trophozoites are found in
cerebrospinal fluid (CSF) and tissue, while flagellated forms are found in
CSF.Acanthamoeba spp. and Balamuthia mandrillaris are opportunistic free-living amebae capable of causing granulomatous amebic encephalitis (GAE) in individuals with compromised immune systems. Acanthamoeba spp. have been found in soil; fresh, brackish, and sea water; sewage; swimming pools; contact lens equipment; medicinal pools; dental treatment units; dialysis machines; heating, ventilating, and air conditioning systems; mammalian cell cultures; vegetables; human nostrils and throats; and human and animal brain, skin, and lung tissues. B. mandrillaris however, has not been isolated from the environment but has been isolated from autopsy specimens of infected humans and animals. Unlike N. fowleri, Acanthamoeba and Balamuthia have only two stages, cysts
and
trophozoites
, in
their life cycle. No flagellated stage exists as part of the life cycle.
The trophozoites replicate by mitosis (nuclear membrane does not remain
intact) .
The trophozoites are the infective forms and are believed to gain entry into
the body through the lower respiratory tract, ulcerated or broken skin and
invade the central nervous system by hematogenous dissemination
.
Acanthamoeba spp. and Balamuthia mandrillaris cysts and
trophozoites are found in tissue.