New England Journal of Medicine releases interim report on Michigan’s cyclosporiasis outbreak

New England Journal of Medicine releases interim report on Michigan’s cyclosporiasis outbreak

The cyclospora outbreak in Michigan this summer was closely linked to iceberg lettuce and a single restaurant chain, according to a new interim report on the outbreak published today in the New England Journal of Medicine.

“Food history data, obtained from 51.3% of patients, indicated that iceberg lettuce and consumption at one restaurant chain were potential exposure sources,” according to the interim report.

The report looked in detail at the early weeks, from May 10 through July 18, which was the beginning of one of the largest outbreaks of the diarrheal illness in U.S. history.

The NEJM interim report does not name the restaurant chain and most of the national Centers for Disease Control alerts and reports referenced identify a supplier, Taylor Farms, but one of the supporting links in the NEJM study goes to a July FDA alert which identifies Taco Bell, and does not name any other restaurant chains, as having stopped its supply from Taylor Farms.

The interim report uses data from 3,114 patients who were interviewed, with 70% of them having eaten at that restaurant chain and 90% of those people having eaten iceberg lettuce. The report notes that there were likely two batches, or one staggered batch, of contaminated food because of bimodal outbreaks in Michigan.

From June 22 through Aug. 26, Michigan had 14,492 cases, 356 reported hospitalizations and two deaths associated with cyclosporiasis.

The NEJM report found that “iceberg lettuce at restaurant Chain A was a strong epidemiologic indicator” but there were many cyclospora patients surveyed in detail who did not recall eating lettuce or at the restaurant.

The study also included chain B, which had 27% of respondents recalling eating there, and chains C and D, which had about 10%.