Interesting article on a possible correlation between chronic fatigue and acute giardiasis. This is apropos to my own case history, as many of my health issues (including CFS and IBS) cropped up after being diagnosed and treated with Giardia.
http://www.research1st.com/2011/09/13/giardia-link/
Full text article from Gut:
http://press.psprings.co.uk/gut/september/gut300220.pdf
