The alarming outbreak of enterohemorrhagic Escherichia coli (EHEC) in Germany has been linked to fresh cucumbers grown in Spain, and perhaps other raw vegetables.  Meanwhile, the epidemic may be spreading to Sweden and other European nations.

(Update: on June 1, 5 days after this story was published, German authorities ruled out Spanish cucumbers as the cause of the outbreak.)

The European Commission late Thursday warned recent visitors to Germany to watch for symptoms, including bloody diarrhea, which could indicate more victims in an outbreak that already has sickened as many as 600, possibly killed five and hospitalized more than 200 with a potentially deadly kidney disease.

On Friday, the Robert Koch Institute, Germany’s national health authority, said more than 60 new cases of hemolytic uremic syndrome (HUS) had been reported in the past 24 hours.

First detected a week ago in Hamburg, the epidemic has been tracked to a still rather unusual strain of bacteria, E. coli 0104:H4, which causes many of the same dangerous effects as the more common and notorious E. coli O157:H7. 

In addition, the German outbreak has resulted in a frighteningly high proportion of life-threatening cases of HUS, a complication of E. coli infection that can lead to kidney failure.  As many as one-third of the known victims — 276 cases — have developed HUS.

German sources yesterday reported that health authorities in Hamburg had isolated the bacterium from four cucumbers, three of which came from a Hamburg market that sells to grocery stores, restaurants and caterers.  The cucumbers were traced to two organic farms in Spain.

According to health authorities in the United Kingdom, organic cucumbers from the Spanish provides of Almeria and Malaga have been identified as the sources of the outbreak, but that a third batch of cucumbers originating from the Netherlands and distributed in Germany is also suspect.

German authorities continue to advise against eating cucumbers from Spain, but also raw tomatoes and lettuce, especially in the north part of the country.

Vegetables had been a primary suspect as a cause of the outbreak because the 70 percent of the victims are adult women.  Most E. coli infections affect young children whose immune systems are less capable of fighting off the poisonous microbes.

Epidemiologists have interviewed many of the victims, seeking common denominators.  Among their findings: Women who have been sickened were far more likely than others to have eaten uncooked tomatoes, cucumbers and lettuce in the early days of the epidemic.

As German authorities groped for clues, illnesses have been detected in neighboring nations, including Sweden, where the Swedish Institute for Communicable Disease Control reported that several adults have fallen ill with E. coli infections, and some have developed HUS. Preliminary lab tests indicate the outbreak strain is likely the one responsible for the illnesses in Germany, and as in the German outbreak, adults are the primary case patients.

E. coli infections possibly linked to the outbreak have also been reported in Denmark, the Netherlands and Britain. The UK’s Health Protection Agency said some of these case patients may have traveled in Germany.

Epidemiologists across Europe and in the U.S. expressed concern about the outbreak, which already compares with some of the worst historical outbreaks of E. coli O157:H7 in the U.S.