Iceberg Lettuce Sourced E. Coli Outbreak Update, Michigan, USA

Main Category: Infectious Diseases / Bacteria / Viruses
Also Included In: GastroIntestinal / Gastroenterology;  Public Health
Article Date: 15 Oct 2008 - 6:00 PDT

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Since September 1, 38 cases of E.coli O157:H7 with the same genetic fingerprint have been reported to Michigan Department of Community Health (MDCH) from various counties. Additionally, nine individuals in Illinois and three from the Province of Ontario have also been identified with the same genetic strain of E. coli O157.

Of the 38 cases, 21 have been hospitalized, and one has developed hemolytic uremic syndrome (HUS). No deaths are known to be associated with this outbreak.

Based upon analysis of scientific evidence from MDCH's epidemiological investigation, iceberg lettuce has been identified as the source of the illness outbreak. Case control studies performed independently in Michigan and in Illinois both identified iceberg lettuce as the common source of illness.

Based upon the product traceback investigation conducted by the MI Department of Agriculture (MDA), Fresh Pak/Aunt Mid's was the common processor of the lettuce supplied to the outbreak locations at MSU, Lenawee County Jail, and in Illinois as well as other foodservice locations identified by ill individuals.

The heads of lettuce being supplied to Aunt Mid's for washing, cutting, and bagging during the outbreak timeframe were identified as lettuce from California. However, the point at which the lettuce was contaminated is still unknown. MDA continues to work in close cooperation with our food safety partners at the California Department of Public Health - Food & Drug Branch who are investigating the origin and handling of the lettuce in that state.

MDA conducted product and environmental sample testing at Aunt Mid's the week of September 26. Additional testing was conducted by the firm, MDCH, MSU, and FDA and all those tests were negative for E.coli. However, those were CURRENT products, not products from the outbreak timeframe.

Lettuce from the outbreak timeframe was not available for testing during the investigation due to the perishable nature of the product.

Aunt Mid's has resumed operations on its iceberg lettuce product line. Aunt Mid's is monitoring and testing each lot of lettuce production over the next 30 days and providing testing documentation to MDA. MDA will also be randomly testing production and checking records.

None of the E. coli illnesses that have occurred within the past two weeks have been linked to this outbreak in Michigan. Because the contaminated iceberg lettuce that caused this outbreak of E. coli O157 is no longer available for consumption, no new illnesses linked to the outbreak are expected to occur. However, as the investigation into illnesses that occurred during the identified outbreak period continues, and additional laboratory results are available, more related cases may be identified and reported. MDCH will continue to conduct surveillance and investigate any new cases of E. coli O157 as they occur.

The product traceback process is lengthy and time-consuming. State and federal investigators need to go through the entire supply chain, sorting records, analyzing data, and case history to determine the origin of the patient's illness and the food source involved.

Source
Michigan Department of Community Health