A mid-summer Salmonella outbreak that sickened at least 124 people across the country probably was due to contaminated shredded lettuce.

At least that’s the opinion of William Keene, senior epidemiologist at Oregon’s Public Health Division.  He told The Oregonian’s Lynne Terry that shredded lettuce is the leading suspect for causing the outbreak.

Keene provided the update on the ongoing investigation by the Centers for Disease Control and Prevention (CDC), U.S. Food & Drug Administration (FDA), and state health departments.

The outbreak ran from mid-July to mid-August with one cluster of cases located in the Portland area where seven became sick and two required hospital stays.  Both were released, but one required re-admittance Monday.

“The woman we represent was hospitalized again today due to complications from her previous intestinal surgery, ” said food safety attorney Drew Falkenstein of Seattle’s Marler Clark law firm.  “We do not know yet how her health is going to be in the future, but we’re going to do everything possible to determine who made her sick.”

“It’s ironic that the announcement about this outbreak comes on September 14,” Falkenstein added.  “We are three years removed from the spinach outbreak. I’d love to be able to say that those were three long, productive years–years spent by lettuce and produce companies researching and developing new ways to control microbial hazards on product that they know will be consumed raw.

“But we have seen outbreak after outbreak after outbreak associated with raw produce–seemingly more now than before spinach.  Whatever the case, I just hope that the retailers whose products were contaminated have been helpful and cooperated with investigating health authorities so that the cause of these illnesses can be identified.”

No deaths were associated with the outbreak.

Salmonella Typhimurium is the strain implicated in the outbreak, which makes the investigation more difficult because it is more common than others.

“We’re trying to learn what happened and what steps can be taken to reduce risk,” Keene told the Oregonian.

Interestingly, Tanimura & Antle, Inc. of Salinas, California expanded the geographic scope of its voluntary recall of bulk and wrapped romaine head lettuce last week due to positive Salmonella tests. 

The company extended the U.S. recall to all 50 states,  Puerto Rico and Canada.  Originally, the recall was issued after a random test conducted by the Wisconsin Department of Agriculture tested positive for Salmonella. 

At the time of the recall no illnesses had been linked to the finding.  Romaine lettuce included in the recall was harvested June 25 – July 2. Shelf life of the product typically is 14 n 16 days.  At this point it is unclear if Tanimura & Antle lettuce is the source of this outbreak.

History of outbreaks involving leafy greens:

November-December 2006 – Shredded lettuce contaminated with E. coli that was served at Taco John’s and Taco Bell restaurants sickened hundreds in the Midwest and East
September 2006 – E. coli-contaminated prewashed, bagged baby spinach sickened 205 across the nation and left five people dead 
June 2005 – E. coli-contaminated Dole prepackaged lettuce sickened thirty in three states
September 2005 – Romaine lettuce contaminated with E. coli O157:H7 left 32 people ill with E. coli infections in Minnesota, Wisconsin, and Oregon
April 2004 – Spinach contaminated with E. coli O157:H7 sickened 16 people in California
October 2003 – E. coli-contaminated pre-washed spinach left thirteen residents of a California retirement facility ill with E. coli infection; two died
September 2003 – Bagged, pre-washed lettuce contaminated with E. coli sickened nearly forty patrons of a California restaurant chain
October 2003-May 2004 – Mixed greens containing E. coli-contaminated lettuce resulted in 57 reported illnesses in California
July-August 2002 – E. coli-contaminated Romaine lettuce sold in Washington state and Idaho left 29 people ill with E. coli infection
October 2003-May 2004 – Mixed greens containing E. coli-contaminated lettuce caused an outbreak that resulted in 57 reported E. coli cases in California
February.-March 1999 – E. coli-contaminated iceberg lettuce caused 72 reported E. coli illnesses in Nebraska
May 1998 – E. coli O157:H7-contaminated salad sickened two in California
May-June 1996 – Lettuce (mesclun; red leaf) contaminated with E. coli O157:H7 caused 61 reported cases in Connecticut, Illinois, and New York
July 1995 – Mixed lettuce contaminated with E. coli O157:H7 led to seventy reported cases in Montana
September 1995 – E. coli-contaminated Romaine lettuce sickened twenty people in Idaho
September 1995 – E. coli-contaminated iceberg lettuce led to an e. coli outbreak with thirty reported cases in Maine
October 1995 – Iceberg was believed to be the source of an E. coli O157:H7 outbreak among 11 people in Ohio Illinois, and New York.

August 1993 – An E. coli O157:H7 outbreak was linked to a salad bar, with 53 reported cases in Washington State.