Dudley said what is surprising about the German outbreak is that this novel E. coli strain is causing an unusually high number of HUS cases.

"Most STEC outbreaks in the past caused HUS in approximately 5 percent of patients, and some outbreaks have seen prevalence as high as 15 percent," he said. "But this German strain is causing HUS in more than 30 percent of patients."

Though nobody knows yet why this strain has caused a greater number of cases of HUS -- more than 700 -- Dudley speculates that the strain's ability to persist in the intestinal tract longer increases the risk for HUS.

"This outbreak is the first evidence that such a strain can cause a devastating illness," he said. "This is a terrible tragedy for all those involved, and we need to understand the reason behind it."

Dudley studies enteroaggregative and Shiga toxin-producing E. coli with an eye toward developing improved methods of tracking the spread of these organisms from farm-to-fork. He has concentrated on understanding the mechanisms that cause certain bacteria to become human pathogens.

"E. coli related to the German strain undoubtedly exist elsewhere in the world, so the big question is whether this outbreak is just a random, isolated case," he said. "It's a very big world out there, and we have a huge food supply. Is this something we won't see for 20 or 30 more years, or is this something we will be seeing with increased regularity?"

Almost nothing is known about where this novel strain of E. coli exists in agricultural settings in Europe or in the United States, Dudley noted. He emphasized the importance of finding out where the German outbreak originated, and with what kind of food.

"In order to understand how to prevent possible future outbreaks, we first must know where this strain originates from, and the routes by which it might transmit to the food supply. We must find out if this is something that is prevalent in our farm environments.

"This is a significant event -- it's the third largest outbreak ever recorded by an E. coli that produces Shiga toxin," he said. "We need to know, was this a one-time event, or is some change in agricultural or other practices heightening our risk for this novel strain?"