After eight weeks, more than 3,700 illnesses and 40 deaths, Germany’s E. coli outbreak is finally waning, but health officials and scientists around the world remain fixed on followup investigations and analysis, anxious to answer some of the crucial questions raised by Europe’s worst epidemic of food poisoning in recent memory.
Among the questions they’re asking:
What is this bug?
Genetic sequencing by two different labs identified the offending microbe as E. coli O104:H4, which carries the same virulent shiga toxin as the more familiar E coli O157:H7. But little is known about this microbe, and scientists are anxious to learn more about it. Stay tuned.
Why does it appear to be more toxic than other E. coli? In an epidemic of E. coli O157:H7, health authorities expect between 5 and 10 percent of the cases to come down with the serious complication call hemolytic uremic syndrome (HUS). Germany reports 857 cases of HUS — three times the normal rate.
It is possible that far more people were sickened, but weathered the diarrhea and recovered without seeking treatment, officials say. Or it could be that German doctors were using different criteria to define HUS, which is essentially a complication of E. coli sickness. Yet the staggering number of deaths would seem to support the German count of 850 HUS cases.
The other theory: This strain is dangerously more toxic than strains that U.S. officials have dealt with. And that is not what officials want to hear.
Either way, what is the risk that this bug will emerge in the U.S.? In the long run, it’s highly probable, experts say.
Food is now a world commodity, routinely shipped around the globe. A microbe that contaminates food in Germany will inevitably cross the Atlantic, and vice versa.
And that may depend in part on how the German sprouts became contaminated, according to Dr. John Kobayashi, a widely respected epidemiologist at the University of Washington. If contamination occurred at the German farm, via an employee or farm animal, then the infection might be contained – though some 3,700 sick people, and perhaps thousands more that were not diagnosed, have become potential carriers.
“But if the seeds were contaminated, then we should be very concerned,” Kobayashi warned. And, based on experience with sprouts, that scenario appears more likely. Sprout seeds are prone to contamination, which can survive washing by “hiding” in the microscopic crevices on the surface of the seed. And if the seeds used at the German farm were the culprit, then contaminated seeds could have been sold and used in other sprout operations.
Why was such a huge outbreak contained to one region?
Most food poisoning outbreaks are relatively small – five or ten people who fall sick after one evening at a local restaurant or church potluck. That’s been changing, because of huge food conglomerates that distribute products coast-to-coast, and because of genetic technology that makes it possible to recognize and regional and national outbreaks and trace them to a source–be it ground beef, peanut butter or raw cookie dough.
Given that, epidemiologists were surprised to learn that the German outbreak was caused by sprouts from a single farm. “It seems strange that the cases are so focused in Germany,” said Kobayashi. “With central contamination, I would expect wider distribution, especially in European countries … Could it be that the implicated food was distributed only within Germany?”
How did German health authorities get sidetracked onto cucumbers?
Experts say Germany’s outbreak was worsened by the fact it took weeks to identify the source. And they remain puzzled by why it took them so long.
From early in the outbreak, they questioned the response at the Robert Koch Institute, the German equivalent to the Centers for Disease Control in the U.S. In the U.S., the standard response to an outbreak is to quickly interview the sickened people, quizzing them about what they have eaten over the previous days and weeks, and where they obtained it. Using standard questionnaires, investigators try to zero in on common denonminators: Did all or most of the victims eat ground beef or chicken or salad? Did they all eat at the same restaurant?
Since virtually all the sick people lived in or had visited northern Germany, investigators should have been able to quickly identify one or more suspect foods, experts say. The greater the number of cases, the easier it should be to find the source.
Timing is crucial, says Dr. Kirk Smith, who directs foodborne illness operations for the Minnesota Department of Health. “The longer you wait, the more people forget and the less likely you will get clear data.”
Meanwhile, every day of delay allows the contaminated food to remain in the marketplace, sickening more people.
RKI’s own report last week acknowledged that its surveillance system was “not sufficient for an adequate response.” Under the German system, local physicians may take up to a week to report food poisoning cases to state authorities, who may take another week to alert national authorities. As a result, it was three weeks before RKI began interviewing patients.
And when they did begin their investigation, RKI decided that the evidence pointed to salad fixings – especially cucumbers. That meant it was another week or more before they corrected themselves and zeroed in on sprouts – which are notoriously susceptible to contamination.