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Why Is This Strain of E. Coli So Hard To Trace And So Dangerous To Health?

  • Charles Recknagel

Spanish MEP Francisco Sosa-Wagner holds a cucumber during a debate in the European Parliament on the recent outbreak of E.coli poisoning in Germany.

Spanish MEP Francisco Sosa-Wagner holds a cucumber during a debate in the European Parliament on the recent outbreak of E.coli poisoning in Germany.

Recent data suggests that there is both good news and bad news about the E. coli outbreak that has killed 21 people in Germany and one in Sweden within a month.

The bad news is that 94 more people fell ill on June 7, raising the number of registered infections in Germany to 2,325. There are also 100 more cases in 10 other European countries and the United States.

The good news – or glimmer of good news – is that the latest figures suggest the number of new cases seems to be declining. If the trend continues, it could be a sign that the epidemic may have reached its peak.

But what the mixed news most clearly illustrates is the continuing difficulty health authorities are having in locating the source of the E. coli epidemic to stop its spread.

That difficulty, experts say, is unfortunately not unusual with this kind of food contamination. First you have to find out what kind of food is carrying the infection and where that food came from before you can remove it from the food chain.

And that can take weeks of painstaking detective work that may – or may not – eventually be successful.

Hugh Pennington, professor emeritus in bacteriology from the University of Aberdeen, maintains that that the evidence increasingly points to bean sprouts as the carrier of the E. coli bacterium whose toxins have poisoned so many people in Germany.

"Bean sprout outbreaks generally are quite large," he says. "They affect mostly women; they affect middle-aged people and the outbreaks go on quite a long time before one gets a handle on them to turn them off," he says

"And this fits the German outbreak extremely well, I am afraid to say, and I think the circumstantial evidence [also] points to this."

Eating The Evidence

But, according to Pennington, even if investigators suspect bean sprouts and currently are focusing on a specific farm in Uelzen, south of Hamburg, there is still no guarantee they will find the smoking gun they are looking for.

The reason is that when disease-bearing foods are eaten, the evidence disappears with them. And that can mean that the investigators arrive too late to follow the trail farther.

"I think the circumstantial evidence points to beans," says Pennington. "But by the time we realize that there is a problem, all of the infected material has been eaten or thrown away so it can be very difficult to prove it."

If the bacterium has come from bean sprouts, the source of the contamination may not be the farm where the beans sprouted but rather the beans themselves

It is not yet known whether this will be the case in Germany. But tests on two German farms strongly suspected of being the source of contaminated bean sprouts have so far failed to reveal any evidence.

The head of Germany's Federal Institute for Risk Assessment, Andreas Hensel, warned on June 7 that "it is possible we shall never be able to identify the source" of the contamination.

Pennington says experience shows that it is likely the source of the contamination may not be the farm where the beans sprouted but rather the beans themselves.

Those beans were probably imported to Germany from a tropical country in the kind of partnership that is becoming increasingly common with the globalization of agribusiness:

"The problem usually is the beans that start the process," he says. "The beans are grown not necessarily in the country where the sprouting is done.

"Very often they are imported from tropical countries and the conditions under which they are grown there may well cause them to be contaminated and in most of the bean sprout outbreaks we are familiar with -- and there have been about 50 so far, not all caused by E. coli -- it is usually the beans that are contaminated.

"So, the farm in Germany, for example, may be doing things absolutely perfectly, they may not be to blame, the beans they were bringing in were probably contaminated and they've…long since [disappeared], as it were."

A Fearsome Legacy

For investigators to follow any international trail to the beans' source would mean months more work.

It also would dramatically raise the possibility that the source might never be found, because records of growing conditions at the farm might or might not have been kept.

This strain of E. coli could be the deadliest in modern history.
In the meantime, the best hope for overcoming the immediate crisis is that the epidemic may peak and recede as consumers stay away from suspect vegetables and infected supplies currently on the market perish and are thrown away.

Still, even if the epidemic were to ease tomorrow, it would leave behind a fearsome legacy.

The epidemic is already considered the deadliest E. coli outbreak in modern history as it confronts scientists with a mutant strain of the bacterium.

The strain, dubbed O104, is far more destructive to the human body, and especially the kidneys, than previously seen strains of E. coli.

"In the German outbreak, between a quarter and a third of the people who are getting infected and having gastroenteritis are going on to develop this kidney complication," says Pennington. "And clearly there have been more than 20 deaths as well, which is an added complication."

The kidney complication he refers to is haemolytic uraemic syndrome (HEU), which is characterized by the breakdown of red blood cells and acute kidney failure.

Pennington says that most people who develop HEU will have only mild kidney damage. Others will require kidney dialysis to get over the acute failure of their kidneys and will suffer enough residual damage that they will need to take medicines to control such resulting conditions as high blood pressure.

But in some cases, the kidney failure can be so catastrophic that the only option – if available – is a kidney transplant.

Pennington says this will leave them having to take immunosuppressant medicines for the rest of their lives, which he describes as a "very poor outcome for those people even though they are not killed by the infection."

The number of victims currently hospitalized in intensive care with HEU is over 640.

Cause May Never Be Known

As investigators in Germany rush now to try to find the source of the deadly E. coli breakout, the sense that they face both a powerful enemy and are running out of time to locate it are increasing daily.

An expert at the World Health Organization (WHO) said on June 7 that "if we don't know the culprit in a week's time, we may never know the cause."

Guenael Rodier, director of communicable diseases at WHO, also said that "right now, [the Germans] are interviewing people about foods they ate about a month ago. It's very hard to know how accurate that information is."

The medical director of Berlin's Charite Hospitals, Ulrich Frei, told reporters today that it took Germany's national disease control center weeks to send his hospital questionnaires for E. coli patients to fill out about their eating habits.

Such criticism is likely to mount in the days ahead as German investigators try to piece together a belated picture of what happened.

"It's like looking at camera footage of a traffic intersection today to see what caused an accident three weeks ago," says Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.

He also described the German effort to tackle the bacteria as "an outbreak response that is not being led by the data."

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