i was just at EBC on the south side last week. it was truly like a refuge camp. took a good 40 minutes to walk from one end of the camp to the other along the Khumbu icefall/glacier. saw and talked to some of the "climbers" there and the Everest circus does live up to its reputation.
so i spent two nights at base camp and those were the only two nights i had stomach issues. this is from a guy that has been in Nepal/India the last 8 months without being sick once. so take it for whatever it is.
this story is not just uncommon but expected. for Western "climbers" it is a sport but for the Sherpa it is their livelihood.
region is still beautiful so people are going to continue to come.