Deadly E coli strain ‘never seen before’

THE E coli bacteria responsible for a mysterious outbreak that has left 18 people dead and sickened hundreds is a new strain that has never been seen before, the World Health Organisation said yesterday.

Preliminary genetic sequencing suggests the strain is a mutant form of two different E coli bacteria, with aggressive genes that could explain why the outbreak appears to be so massive and dangerous, the agency said.

“This is a unique strain that has never been isolated from patients before,” said Hilde Kruse, a food safety expert at WHO. The new strain has “various characteristics that make it more virulent and toxin-producing” than the many E coli strains people naturally carry in their intestines.

Researchers have so far been unable to pinpoint the cause of the illness, which has now spread to at least 10 European countries and fanned uncertainty about eating tomatoes, cucumbers and lettuce. The strain has sickened more than 1,600 people, including 470 who have developed a rare kidney failure complication, and killed 18 — most of them in Germany.

Fearful of the outbreak spreading east to Russia, the country extended a ban on vegetables to the entire European Union from just Germany and Spain, a move the bloc quickly called disproportionate.

Scientists sequencing the bacteria strains found in the outbreak said it was caused by “an entirely new super-toxic E coli strain” that several antibiotic resistant genes, according to a statement from the Shenzhen, China-based laboratory, BGI. The researchers were working together with scientists from the University Medical Centre Hamburg-Eppendorf.

The scientists found the bacteria is similar to a strain isolated in the Central African Republic known to cause serious diarrhoea, the Chinese lab said.

Kruse said it’s not uncommon for bacteria to continually mutate, evolving and swapping genes. It is difficult to explain where the new strain came from, she said, but said strains of bacteria from both humans and animals easily trade genes, similar to how animal viruses like Ebola sometimes jump into humans.

“One should think of an animal source,” Kruse said. “Many animals are hosts of various types of toxin-producing E coli.” Some scientists suspect the deadly E coli might have originated in contaminated manure used to fertilise vegetables.

Previous E coli outbreaks have mainly hit children and the elderly, but the European outbreak is disproportionately affecting adults, especially women.

Kruse cautioned that since people with milder cases probably aren’t seeking medical help, officials don’t know just how big the outbreak is. “It’s hard to say how virulent (this new E coli strain) is because we just don’t know the real number of people affected.”

Nearly all the sick people either live in Germany or recently travelled there.

The WHO recommends that to avoid food-borne illnesses people wash their hands before eating or cooking food, separating raw and cooked meat from other foods, thoroughly cooking food, and washing fruits and vegetables.

One expert said the fact the strain is new may have complicated the response to the outbreak. “Officials may not have had the correct tests to detect it, which may explain the initial delay in reporting,” said Paul Hunter, a professor of health protection at the University of East Anglia in England.

He said the number of new cases would likely slow to a trickle in the next few days. The incubation period for this type of E coli is about three to eight days, and most people recover within 10 days.