Free-living amoeba can be found in many habitats but water is an important source of human exposure.


Water sources that may be contaminated with free-living amoebae:

(1) freshwater lake or pond

(2) hot springs

(3) water outflow from a power plant

(4) river or stream

(5) bayou or swamp

(6) drainage ditch or irrigation canal

(7) retention or oxidation pond


The risk is increased when the water is warm. Late summer when the water is warm and water volume is low is a high risk period.


Water-related activities:

(1) swimming

(2) diving

(3) water skiing

(4) wakeboarding or tubing

(5) digging in or stirring up sediment


Wearing a nose clip or pinching the nose when diving can reduce the introduction of contaminated water into the nose.


Special precautions should be taken with risk factors for amebic encephalitis:

(1) HIV

(2) transplant recipient

(3) steroid therapy

(4) immunosuppression

(5) SLE

(6) diabetes mellitus

(7) alcoholism

(8) chronic liver disease

(9) malignancy

(10) pregnancy


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