Health workers rushed Wednesday to contain an outbreak of acute diarrhea afflicting hundreds of earthquake survivors at a crowded, unsanitary camp on a soccer field here in the capital of Pakistan's part of Kashmir. Tent camps have sprung up in towns and cities across the region, housing local residents and people who fled distant villages that relief workers have struggled to reach. Most camps were set up with official sanction and have sanitary facilities. But others have grown haphazardly wherever people find space, such as the camp on the sports field next to the devastated university in Muzaffarabad, the main city of Pakistani Kashmir.Since the quake, about 3,000 people have gravitated to the field. Living in tents, many barely a yard apart, they share a handful of clogged latrines and wash themselves above a stinking ditch of stagnant water. Humanity First, a German charity that provides health care at the camp, reported an alarming rise in acute diarrhea cases, including dysentery, in the past week. Dr. John Watson of the World Health Organization said more than 200 such cases had been reported at the camp in the past week — none fatal. Acute diarrhea can cause life-threatening dehydration and can indicate the presence of deadly illnesses like as cholera, but WHO officials said there was no immediate evidence of that at the camp.