The creatures, brain eating amoebas, are mostly a bacteria eating organism (actually not amoebas). They are not normally pathogens on people. The cases I have read about are typically with people with some issue that makes it possible for them to infect people. They could be all around us but we never know because we are not exposed to enough at one time to overcome our natural resistance. Below is a quote from a site on the CDC on occurrences in the US:
Also from the CDC:
Given the last quote I think I will start to use a PFD for my water changes, don't want to drown.
Joking aside, I wouldn't worry about it in the slightest. But the House episode was pretty entertaining.
Frequently asked questions about naegleria. Education and information about the brain eating ameba Naegleria fowleri that causes encephalitis and death including frequently asked questions, biology, sources of infection, diagnosis, treatment, prevention and control, and other publications and...
www.cdc.gov