Which waterborne disease, caused by a protozoan present in the intestinal tract of both humans and wild animals, may occur among campers in wilderness areas who unwittingly swallow pathogenic cysts when they drink unfiltered water from mountain streams?

The waterborne disease that is caused by the protozoan present in both humans and wild animals' intestinal tract, that also occurs to the campers who are staying in the wilderness areas and were able to swallow pathogenic cysts when they are able to drink the water that is not even unfiltered, the water they usually drink are from the mountain and stream and the one responsible for it is the giardiasis.