lol @ Dusty!
i'd never heard of this before, so i just looked it up on Wiki -
http://en.wikipedia.org/wiki/Giardiasis
considering the nature of Giardiasis, and what it does to the intestinal lining, it does sound quite feasible to me that it could be a factor in developing IBD...
i also found this - really interesting reading -
http://www.ncbi.nlm.nih.gov/pubmed/3227299
"giardiasis is a common finding in patients with Crohn's disease. Treatment of giardiasis can, in individual cases of Crohn's disease, result in a quick recovery from symptoms of high disease activity."