Well, I've read stuff saying there is doubt that giardia can survive through the winter, and the area had been washed by many feet of snow melting away. And I still doubt I got the giardia from the hike.
While looking for info on a similar subject posted on the WPSMB, I ran across this research article:
Quoted from
Effects of the Norwegian winter environment on Giardia cysts and Cryptosporidium oocysts
"Shear forces generated during freeze-thaw cycles are postulated to have disintegrated the parasites exposed to the Norwegian winter and retrospective laboratory studies support this theory. Increased dye inclusion, possibly indicative of viability loss, was also noted. The refrigerated control parasites exhibited no decline in numbers, and alteration in dye inclusion characteristics for refrigerated parasites was slower. Cryptosporidium oocysts were apparently more robust than Giardia cysts; differences between isolates were also noted. These results suggest Cryptosporidium oocysts and Giardia cysts do not persist in the Norwegian terrestrial environment over winter, and when detected, will have been excreted since the previous winter. Differences in the morphological characteristics, matrix effects, and the possible relationship of the dye data to parasite survival are discussed in relation to further studies."
http://www.ncbi.nlm.nih.gov/pubmed/14749905
