Beaver Fever (it's not what you think)
Giardiasis (beaver fever) can be contracted through beaver feces and can cause serious symptoms especially in children.
Here is a website < http://www.cdc.gov/Ncidod/dpd/parasites/giardiasis/default.htm> that gives you idea of what this is all about. My understanding is that Beavers are well known to carry this bacteria, more beavers mean more chance and the higher the nutrient load in the lake will mean the easier it will be for this bacteria to live in our water.