BERLIN—An unusually lethal strain of E. coli bacteria has infected more than 1,500 people in Germany, mystifying public health officials, ravaging Spain’s agricultural heartland, and touching off panic in Europe as people weighed whether it was safe to eat raw vegetables.
The source of the outbreak, similar to the bacteria involved in the Walkerton, Ont., tragedy 11 years ago, remained unknown. It has killed at least 16 people, 15 in Germany and a Swede who visited there recently.
Public health officials are alarmed because a startlingly high proportion of those infected suffer from a potentially lethal complication attacking the kidneys, called hemolytic uremic syndrome, which can provoke comas, seizures and stroke. Dr. Robert Tauxe, deputy director of food-borne disease at the Centers for Disease Control and Prevention in Atlanta, said the rate of cases of acute kidney failure in the outbreak was unprecedented. “That makes this an extraordinarily large and severe event,” he said.
While most of the infections were among people who had traveled to northern Germany, the authorities acknowledged that the outbreak had spread to virtually every corner of the country.
Shoppers and vegetable-sellers in Berlin expressed a blend of confusion, anger and stoicism; about 20 cases of E. coli infection have been reported in the capital city.
“A lot of people are afraid or worried,” said Nursan Usta, 43, who runs a fruit and vegetable stall in Berlin’s blue-collar Neukölln district. “They aren’t even buying cherries” — even though the authorities have only mentioned cucumbers, lettuce and tomatoes as potential sources of infection.
In Motril, a town in Spain’s agricultural heartland, greenhouses were empty of workers as demand for vegetables collapsed after the German authorities initially — and most likely mistakenly — pointed to Spain as a source of the outbreak.
“Working in a greenhouse can be tough, but I’ve never felt more exhausted and empty inside than now,” said Miguel Rodríguez Puentedura, who had been picking cucumbers until Monday, when the greenhouse that employed him shut down.
Health officials in Hamburg, the centre of the outbreak, appealed Wednesday for donors to contribute blood. “We need extra blood for the critically ill patients,” said Singje Köpke, a spokeswoman for the Institute of Hygiene and Environment.
Scientists are at a loss to explain why this little-known organism, identified as E. coli 0104:H4, has proven so virulent.
The European authorities have reported several differences from previous outbreaks, including that women make up more than two-thirds of those affected and that young and middle-aged adults account for a very high percentage of the most severe cases. Dr. J. Glenn Morris, director of the Emerging Pathogens Institute of the University of Florida, said the German strain may have undergone genetic changes or mutations to make it more potent.
Cases that feature acute kidney failure represent a much higher percentage of the total number of illnesses than in previous outbreaks associated with different strains of E. coli. Generally, 5 to 10 percent of E. coli illnesses result in this complication. Among the confirmed cases, according to the Robert Koch Institute, Germany’s disease control agency, 470 people had been diagnosed with the kidney syndrome.
That could be because German doctors are using a broader definition of kidney failure that captures more cases. Or it could mean that the total number of illnesses is much greater than has so far been revealed, which ultimately would lower the percentage of acute cases. Or it could be a signature of this form of E. coli.
There are many types of E. coli, most of which are harmless. But a small number have come under increasing scrutiny as dangerous pathogens. These all produce a poison known as shiga toxin and generally have the ability to cling to a person’s intestinal wall, allowing them to release the poison in large enough amounts to make people sick.
Dr. Phillip Tarr, a professor of microbiology at the Washington University School of Medicine in St. Louis, said that there were two main forms of shiga toxin found in E. coli, and that the strain detected in the outbreak in Germany appeared to have the more potent version of the poison. But he said the organism appeared to have other quirks that made it unusual, and potentially difficult to detect by conventional means.
“This outbreak is still evolving and everyone is still in the fog of case definition,” Tarr said. With the source of the contagion unknown, the Robert Koch Institute on Wednesday warned against eating raw tomatoes, cucumbers and lettuce, particularly in northern Germany.
European and German officials pledged to track down the cause of the outbreak and to pinpoint where in the food supply chain the contamination had taken place.
“Hundreds of tests have been done,” the German agriculture minister, Ilse Aigner , said in a television interview. So far, those tests had determined that “most of the patients who have fallen ill ate cucumbers, tomatoes and leaf lettuce, primarily in northern Germany.”
Two people in the United States were hospitalized with kidney failure after returning from travel to Hamburg, Dr. Tauxe, of the Centers for Disease Control, said. He said tests were being done to see if they were sick with a strain of E. coli that matches the German strain.
Tarr said the outbreak in Germany pointed to a basic gap in public health systems worldwide. If samples from sick patients were routinely tested for the presence of shiga toxin, it could lead to much faster identification of problems — and quicker action to identify the source of an outbreak and stop its spread.
After a lethal outbreak of E. coli in 1993, Tauxe said the United States created a government database that gathered information on laboratory testing of pathogens and shared it with health officials around the country. He said no similar system existed in Europe that would allow separate countries to quickly share lab results.
“This could be an important game-changing event in Europe,” he said.
Despite the mood of alarm, John Dalli , the European Union health commissioner, told a news conference in Brussels that the outbreak was on the decline, with fewer hospitalizations in recent days.
“We would therefore consider a ban on any product as disproportionate,” Dalli said.
Tests by the German authorities on Spanish cucumbers had identified some E. coli, Dalli said. But those tests had not identified the highly virulent strain that had led to such serious health problems. “There is no proof at this point in time that the Spanish cucumbers are the cause of this contamination in Germany,” he said.
Still, some shoppers remained wary. In a store specializing in organically grown produce in the upscale Wilmersdorf area of the capital, Miriam Schäfer, a sales attendant, said Spanish cucumbers had been removed from the shelves — even though they were no longer the direct suspects — and replaced by locally grown ones. “People are buying less,” she said. “They are asking a lot of questions about what is safe.”
But some shoppers insisted the risk was minimal. The cause of the outbreak “is not yet proven,” said Corinna Kasper, 24. “First they say it’s one thing and then another.”
European farmers sought to pre-empt economic damage caused by the outbreak. “It is totally unacceptable to impose trade bans when the source of contamination remains unknown,” said Pekka Pesonen , the secretary general of Copa-Cogeca, a group representing European farmers and cooperatives.
Major growers in Germany are losing up to $7 million daily and two-thirds of all vegetables, including lettuce and tomatoes, produced by his members were being destroyed, according to Karl Schmitz, the director of the German Federal Association of Producers of Fruit and Vegetables. In Spain, the damage is much broader, estimated at about $286 million a week.