E. coli bacteria kills 18 Germans, sickens hundreds across 10 countries

Europe's latest scourge is a bug like no other.

The E. coli bacteria blamed for killing 18 Germans and sickening hundreds more in nine other countries is a new strain that has never been seen before, the World Health Organization said Thursday.

Lab tests point to a mutant form of two different E. coli bacteria, with aggressive genes that help explain why the outbreak has been so massive and deadly, the agency said.

\"This is a unique strain that has never been isolated from patients before,\" Hilde Kruse, a food safety expert at the WHO, told The Associated Press.

The killer strain has \"various characteristics that make it more virulent and toxin-producing\" than the many E. coli strains that live in peoples' intestines, Kruse said.

Scientists are scurrying to determine how to fight back against the bacteria. (Colin Anderson/Getty)

How lethal is the new bug? Most of the time, E. coli poses a deadly threat to very young children or to elderly people who are already sick.

This time, two-thirds of the most sickened people have been otherwise healthy women and middle-aged adults.

And of the more than 1,500 people who have been sickened by the mutant E. coli strain, a third have developed a rare kidney failure complication.

Researchers initially thought Spanish cucumbers were to blame for the outbreak, but now scientists suspect the new strain might have originated in contaminated manure used to fertilize vegetables elsewhere.

That's little comfort to Spanish farmers, who lost hundreds of millions of dollars when their produce was pulled off store shelves.