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Balamuthia mandrillaris • GAE + granulomatous skin and lung lesions
(primarily healthy)
Pathogenic Free-Living Amebae
low nutrients
desiccation
Naegleria Life Cycle
Cyst = dormant form
Trophozoite =feeding and replicating form
Naegleria fowleri• ubiquitous genus found in fresh water
lakes and ponds• PAM first recognized by Fowler (1965)
• initially thought to be Acanthamoeba
• Naegleria fowleri is only species associated with PAM
• ~ 200 documented cases worldwide• 81 in U.S.• 14 cases from same lake in Virginia• 16 cases from same stream feed pool in
Czech Republic
Primary Amebic Meningoencephalitis (PAM)• 1-14 days incubation period• symptoms usually within a few days after
swimming in warm still waters• infection believed to be introduced through
nasal cavity and olfactory bulbs• symptoms include headache, lethargy,
disorientation, coma• rapid clinical course, death in 4-5 days after
onset of symptoms• trophozoites can be detected in spinal fluid, but
diagnosis is usually at autopsy• 4 known survivors treated with Amphotericin B
brain sectionin vitro culture
“lobopodia”
Acanthamoeba life cycle
Acanthamoeba• ubiqutous ameba of the soil and water • Culbertson (1958) fortuitously produced
disease in mice (culture contaminant)• human cases first reported in the early 70's• 73 cases worldwide of GAE as of 1991
• 39 in U.S.• majority of patients are chronically ill,
immunocompromised, or debilitated with other diseases
• also produces amebic keratitis and skin and lung lesions
Acanthamoeba Meningoencephalitis
• portal of entry unknown, possibly respiratory tract, eyes, skin
• presumed hematogenous dissemination to the CNS• infection associated with debilitation or
immunosuppression• onset is insidious with headache, personality
changes, slight fever• progresses to coma and death in weeks to months• amebas not yet detected in spinal fluid• trophozoites and sometimes cysts detectable in
histological examination• no human cures documented
both Acanthamoeba and Balamuthia• no intravascular ameba (this study and literature)• perivascular infiltration frequently observed• propose perivascular route from primary mucosal
lesion
Red Tides• ‘blooms’ of dinoflagellates
• phyto- and zooplankton• usually monospecific
• rapid population increase• nutrients, lack of grazing,