Dr. Christopher Braden, the chief of food- and waterborne diseases at the Centers for Disease Control and Prevention, doesn't expect the Escherichia coli bug causing serious illness in northern Europe to leapfrog the Atlantic anytime soon.
Still, Braden tells Shots, "I am concerned about something similar that could happen in the United States."
That's because the U.S. already sees "quite a few infections every year" from Shiga-toxin-producing E. coli. That's the dangerous kind that can destroy blood cells, clog arteries, cause intestinal bleeding and lead to kidney failure and death.
And a big change has been going on in the type of toxin-producing E. coli causing illness here. An increasing number are so-called "non-O157" types, including the O104 type of bug behind the current European outbreak.
The specific type involved in the European outbreak is O104:H4. Braden says CDC investigators first saw it two years ago in the Republic of Georgia in eastern Europe. At that point it hadn't acquired all the antibiotic resistance genes that the current strain has, Braden says, "but close enough that we would say they're very similar."
The chief culprit in serious E. coli cases used to be a notorious type called O157:H7. It caused a big outbreak in hamburger back in 1982 and in raw spinach five years ago. In between it touched off two dozen other U.S. outbreaks.
"For a number of years, almost all of the strains of this kind of E. coli were that O157:H7," says Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. "Over the past 15 years, we've seen a very sizable increase in the number of non-O157:H7 strains."
That's thought to be due in large part to improvements food safety aimed at detecting and eliminating O157 strains from the food supply. But that has opened a path for other types of toxin-producing strains — of which there are hundreds.
It's unclear how many of these non-O157 strains are involved in U.S. food-borne infections because they're harder to test for. "But when we do studies looking for them, they make up well over half of all the hemorrhagic E. coli illnesses out there," Osterholm tells Shots. "And we think that number is actually increasing, not decreasing."
Officials estimate that at least 100,000 Americans suffer E. coli infections from toxin-producing organisms every year, sending thousands to the hospital and killing about 80 people. That's a much bigger toll than the current German-centered outbreak — more than 2,400 cases, including more than 600 cases of kidney failure, and 23 deaths. But most cases occur one-by-one, not in big outbreaks.
There's controversy over why the European bug is so bad.
Some experts think it's not really more dangerous than earlier strains. It's just that more people got exposed to it, or perhaps there was an unusually high level of contamination on whatever foods affected people ate.
Another hypothesis: Perhaps some of the most seriously ill cases were treated with antibiotics. Paradoxically, some think that can make matters worse. Some say that's because more toxin is released from the E. coli that are killed off. Others think, in the case of a highly antibiotic-resistant bug like O104:H4, antibiotics kill off other intestinal flora but not the E. coli, leaving them a clear field.
University of Wisconsin infectious disease specialist Dr. Dennis Maki dismisses these theories. He has treated lots of people with bad E. coli infections over the years, and he says this one is clearly different.
Earlier strains were far less likely to put victims in the hospital with severe anemia and kidney failure, Braden says, with "rarely over 10 percent" of patients affected.
By contrast, Maki notes the European strain is hospitalizing about a third of its victims. "That's extraordinary," he tells Shots. "This is an extraordinarily virulent strain of E. coli. I think that's becoming clear."
Maki predicts that "we will see U.S. cases" of the European bug as it gets carried back to North America by travelers. "We could have a big outbreak with this strain in a year or two or three," he says. "It's not out of the question at all."
Osterholm agrees that the bug will get around. "Are there going to be more outbreaks like we see in Germany right now occurring around the world?" he says. "I bet you there will be."
That's why experts want to learn everything they can about the European bug - how it got there, why it's so deadly, and above all, how it gets into food.