Associated Press
 
November 30, 2009
 
PORTLAND, Ore. -- Health officials say they haven't seen evidence of an outbreak of human sickness linked to the contamination of a Portland reservoir and say they may not find the source of the contamination.
 
Officials say they're trying to find a laboratory that could do DNA testing of the E. coli bacteria, but health officer Dr. Gary Oxman says such testing might not be readily available.
 
Some kinds of E. coli prefer birds as hosts. Others prefer humans, cattle or other animals.
 
Officials have lifted their notice advising water customers west of the Willamette River to boil the water they consume.