Health officials are investigating the source of the contamination of leafy salad greens by a potentially deadly strain of E. coli bacteria, the likely cause of 24 illnesses in 15 states and two deaths in the United States and Canada.
Although there have been no reported illnesses since Dec. 12 in this country, U.S. health officials are still looking into which leafy greens may have caused the illnesses and how an animal pathogen found its way into salad products sold nationwide. Government health officials in Canada, who weeks ago linked 42 illnesses and one death to romaine lettuce, officially called an end to the outbreak in that country earlier this week.
Experts in food safety and public health say the bacterial strain at the epicenter of both the U.S. and Canadian outbreaks — E. coli O157:H7 — is one of the most virulent to contaminate the food supply. And the outbreak is the worst involving salad greens since the devastating one in 2006 linked to spinach.
“We all have E. coli in our own intestines, so it is not uncommon. It is this particular strain that is a problem because it produces a shiga toxin,” said Dr. Brian Harper, medical director for the academic health center at NYIT College of Osteopathic Medicine in Old Westbury and a former Suffolk County health commissioner.
Shiga toxin is a poisonous secretion of this strain of E. coli and is closely related to the toxin of Shigella bacteria, which can cause fatal dysentery.
E. coli O157:H7 can cause profuse bloody diarrhea and a post-diarrheal condition called uremic syndrome, a severe, life-threatening complication affecting about 10 percent of people infected with E. coli O157:H7.
Harper said infections with this strain of E. coli are a “reportable disease” in New York, which means any diagnosis involving the pathogen must be reported to the New York Department of Health because of the bacterium’s virulence. A spokeswoman for the health department Thursday said there was one case in the state linked to the current outbreak involving leafy salad greens. The patient was diagnosed in New York City, she said.
Jean Halloran, director of food policy initiatives at Consumers Union, the policy division of Consumer Reports, said her organization had urged federal health agencies to take more aggressive steps to identify the outbreak’s source.
“This pathogen is most famous for showing up in brown meat because it lives in the guts of cattle,” Halloran told Newsday on Thursday.
“The reported illnesses are just the tip of the iceberg. You have 24 reported illnesses, the people who got really sick enough to go to the hospital and you have to be pretty sick for that to happen. But for each of those people there are probably five to 10 who felt really horrible for a day or so and got over it on their own.
“We really want them to make a big effort to find out where this came from and what the source is,” Halloran said. “Even if we don’t have cases for a while, we need to know where it came from because the contamination can recur.”
The Centers for Disease Control and Prevention said in a statement that it is working with the U.S. Food and Drug Administration as well as state health departments and the Canadian Food Inspection Agency to identify the contamination’s source.