Investigators from the U.S. Centers for Disease Control and Prevention and Missouri's health department were in St. Louis on Friday trying to determine the cause of an E. coli outbreak that sickened nearly two dozen people in the city and four surrounding counties.
No one has died but at least six people required hospital stays. Health officials weren't certain when they'd be able to pinpoint the cause, or even if there was a single cause, said John Shelton, spokesman for the St. Louis County Health Department. The first cases were reported earlier this week.
"What we look for is a common link among the patients to determine if everyone got the illness from a single source," Shelton said. "In this case, we have not encountered any common element among the patients."
Grocery stores have not been asked to remove any food, but the region's largest supermarket chain, Schnuck Markets Inc., took voluntary action by taking some items from its in-store salad bars. The chain operates 65 area stores.
Sixteen of the victims are from St. Louis County, ranging in age from 4 to 94. At least six others are from St. Louis city, Jefferson and St. Charles counties in Missouri and St. Clair County, Ill. Officials fear the number could grow because the incubation period for E. coli is 10 days.
E. coli are a group of bacteria that can cause diarrhea, urinary tract infections, respiratory illness and pneumonia. The illness is typically spread through consumption of contaminated food, unpasteurized milk, contaminated water or contact with the feces of infected people.
Young children and the elderly are most at risk of serious illness which can, in rare instances, be fatal. Health officials encouraged immediate medical attention for anyone with bloody or persistent diarrhea, severe stomach cramps or nausea.
Schnuck's spokeswoman Lori Willis said there was no indication any items causing E. coli were purchased at those stores, but the company's food safety team researched what types of foods could be a source and removed them. She declined to name the items removed, saying doing so would be unfair to the vendors because health officials have given no indication of a potential source.
"We were trying to proactively do whatever we could to make sure we were on top of this issue," Willis said.
The other two big grocery chains in St. Louis, Dierberg Markets Inc. and Shop 'n Save, have not removed any items because they've been given no indication of a possible source of the E. coli, representatives said.
In August, one person died and 14 others became ill in an E. coli outbreak in Oregon. Health experts believe deer droppings in a strawberry field caused the outbreak.
The most recent E. coli outbreak linked to produce was in May 2010 and involved romaine lettuce. Missouri was not part of that outbreak, according to the CDC.
Also last year, more than three dozen people in five western states were sickened by E. coli contamination caused by cheese.
Health officials encourage people to wash hands thoroughly, especially after going to the bathroom; wash produce and cooking equipment; and cook all meats to at least 167 degrees, the level at which germs are killed.