A deadly new E. Coli bacterium that is spreading rapidly through Europe has doctors and scientists stumped.
According to NPR, the new E. Coli strain is so virulent and deadly that it is "very rare" and has never been seen in an outbreak form before.
The new bacterium is similar to the E. Coli strain that doctors have seen in the United States. But the new strain is resistant to most antibiotics and it has a different method of making people ill.
The bacterium causes full-blown haemolytic uraemic syndrome (HUS), a condition that results in bloody diarrhea and large volume of blood in urine.
So far, 18 people have died, and 470 people have been sickened in Europe since the World Health Organization (WHO) sounded the alarm on May 20.
The new strain of E. Coli attaches itself to the intestinal walls and releases a deadly toxin that is absorbed through the intestinal walls into the bloodstream.
"What we think happens is the toxins get into the blood stream and injure the blood vessels. And the blood vessels form little clots, and there's impaired blood flow to organs throughout the body," said Dr. Phillip Tarr from Washington University in St. Louis.
This type of serious injury to blood vessels leads to kidney and liver failure, and can cause death. More than half of the people sickened by the new E. Coli require kidney dialysis.
"In almost all cases it's temporary," Dr. Tarr says. "Dialysis lasts a median of about 8 days."
But dialysis doesn't save everybody -- as evidenced by the 18 people who died in Europe in the last 2 weeks.
Surveys of people who got sick found they were more likely to have eaten fresh tomatoes, lettuce and cucumbers. But tracing fresh vegetables back to the original farm source can be difficult.
Besides that, if the contaminated food is a fresh vegetable, the normal food safety tips won't necessarily protect you.
"Unfortunately these bacteria tend to be sticky and it's difficult to wash them off fresh vegetables," says Tauxe. "And sometimes they're even inside."
Three new cases are suspected in the United States. The CDC is awaiting test results before making that determination. All three people visited Europe within the last two weeks. No deaths have been reported in the U.S. yet.