Lettuce Parasite Outbreak Hits 10,930 Cases, Two Deaths

The 17 states on the CDC's outbreak list are Arkansas, Iowa, Illinois, Indiana, Kansas, Kentucky, Massachusetts, Maine, Michigan, Missouri, Nebraska, New Hampshire, North Carolina, Ohio, Oklahoma, Pennsylvania and West Virginia. The count includes people who got sick while traveling in one of those states but live elsewhere.

Michigan is the hardest-hit state and is where both deaths occurred. Within Michigan, Wayne County has the most cases at 2,029, followed by Oakland County at 1,499, and the 30-to-39 age group accounts for the most infections at 2,879, per Reuters. Ohio has reported 3,299 cyclosporiasis cases in its northwestern counties alone, Food Safety Magazine reported Aug. 14.

Those two surveillance figures added together are the source of the roughly 27,000 national case number appearing in some coverage this week. Most of those cases are not linked to the recalled lettuce. The FDA is investigating six other cyclosporiasis clusters — accounting for 2, 8, 11, 18, 25 and 172 illnesses — and has not identified a food source for any of them, Food Safety Magazine reported.

For scale: 1,180 cyclosporiasis cases were reported nationally between May 1 and Aug. 31 of last year.

Cyclospora is unusually hard to catch in a product test. It cannot be grown in a laboratory, and unlike many foodborne pathogens it cannot be identified with the most advanced genetic testing methods. "Because we cannot grow Cyclospora in the lab, testing of food or environmental samples depends on the sensitivity of the test... and concentration of the organism on the food sample," Craig Hedberg, a professor of environmental health sciences at the University of Minnesota, told CIDRAP. "They are usually very low."

The recalled lettuce was distributed and sold in at least 31 states, according to the CDC. The FDA says the best-by dates have passed and the product should no longer be in stores or restaurants.

The traceback started at Taco Bell. The FDA's investigation identified convergence on a single supplier — Taylor Farms de Mexico — that provided shredded iceberg lettuce to the Taco Bell locations where sick people had eaten, initially across Indiana, Kentucky, Michigan, Ohio and West Virginia. Not all Taco Bell locations in those states used the same supplier. The Michigan health department analyzed food exposures for 190 cases who reported eating at Taco Bell and found 90 percent of them had eaten iceberg lettuce, then passed the finding to the CDC.

Symptoms, per the FDA, include watery diarrhea with frequent bowel movements, loss of appetite, weight loss, stomach cramps, bloating, increased gas, nausea and fatigue. Vomiting, body aches, headache and fever can occur. Untreated, the illness can lead to dehydration and complications lasting from a few days to a month or more, and symptoms can seem to clear and then relapse. People with weakened immune systems can get sicker for longer.

Symptoms typically take one to two weeks to appear after exposure, which is a large part of why this outbreak has been so hard to trace.

Three outbreaks, not one

Several food safety stories are running at the same time this month and are being conflated. They are separate outbreaks with separate causes and separate products.

The lettuce outbreak described above is caused by Cyclospora cayetanensis, a microscopic parasite, and is linked to recalled Taylor Farms de Mexico iceberg lettuce.

A different outbreak involves alfalfa sprouts in Minnesota and Wisconsin, which health officials have linked to bacteria — not a parasite — and a different supplier.

A third involves salmonella tied to jalapenos, which has grown past 400 cases nationally. Also a different pathogen, a different food and a different investigation.

None of the counts in this article include cases from those two outbreaks.