The CDC’s final outbreak report, issued September 11, revealed a staggering 12,883 confirmed illnesses across 21 states.
At least 570 people were hospitalized.
Two deaths were reported, both in Michigan.
Federal health officials say the outbreak has now ended and the contaminated lettuce is no longer being sold or served. Most illnesses occurred before the affected products were recalled on July 17.
The outbreak became one of the year’s most significant food-safety events.
At its peak, according to the CDC, more than 1,000 infections occurred in a single day.
Cases later collapsed dramatically. By August, fewer than two new infections per day were occurring on average.
The CDC warned that the actual number of Americans infected may have been considerably higher than the official count because people with mild illnesses may recover without seeking medical attention or being tested.
The Michigan deaths were particularly notable because fatal cases of cyclosporiasis are extraordinarily unusual.
Michigan had experienced an explosive rise in cases earlier in the summer.
State health officials announced on July 1 that more than 170 infections had been identified in just nine days in several counties. Michigan ordinarily records only about 50 cases during an entire year.
Dr. Natasha Bagdasarian, Michigan’s chief medical executive, warned at the time that officials expected the numbers to continue climbing.
“Outbreaks of cyclosporiasis have been occurring across the United States and now here in Michigan,” Bagdasarian said. “Based on the unusual number of cases we have identified in a little over a week, we anticipate additional cases of illness being reported. We recommend Michiganders contact their health care provider if they experience sudden, ongoing diarrhea and reach out to their local health department if additional members of their family are suffering from the same symptoms.”
That warning proved well-founded.
By early August, Michigan authorities reported more than 12,000 cyclosporiasis cases in the state since June, although not every reported Michigan illness was necessarily part of the specific lettuce-linked multistate outbreak.
What Is Cyclospora?
Unlike familiar foodborne bacteria such as Salmonella or E. coli, Cyclospora is a parasite.
People can become infected after consuming food or water contaminated with the parasite.
The resulting disease, cyclosporiasis, primarily attacks the intestinal system and can cause prolonged gastrointestinal problems.
Common symptoms include watery diarrhea, loss of appetite, weight loss, stomach cramps, bloating, nausea and fatigue. Some patients may also experience fever or muscle aches.
Symptoms generally begin about a week after infection.
Without treatment, the illness can drag on for weeks or even longer, sometimes disappearing and then returning.
One of the biggest concerns is dehydration, particularly for older patients and people already dealing with serious medical conditions.
Patients experiencing symptoms are advised to remain hydrated and contact a health care provider. Testing for Cyclospora may need to be specifically requested because the parasite is not necessarily detected through every routine laboratory test.
Imported Lettuce Identified as Source
Investigators initially struggled to determine what was driving the sudden wave of illnesses.
Michigan officials said in early July that lettuce and salad greens repeatedly appeared during interviews with infected patients, but authorities initially could not identify a specific product or supplier.
“Although we do not have a definite product identified as the source of the outbreak, we want to let Michiganders know what we have learned so far so they can take steps to protect their families,” Bagdasarian said on July 13. “Early information has shown lettuce as a common product that regularly comes up during the investigation. We will continue to provide updates as we learn more.”
Federal investigators ultimately traced the major multistate outbreak to processed iceberg lettuce supplied by Taylor Farms de Mexico.
The lettuce had been distributed to multiple locations, including certain Taco Bell restaurants. The investigation eventually expanded well beyond the states initially identified.
Illnesses associated with the outbreak began June 14 and continued through August 17.
The affected lettuce was recalled in July, and the relevant best-by dates have since passed.
The CDC formally declared the outbreak over on September 11.
However, the Food and Drug Administration was still investigating exactly how the lettuce became contaminated when the CDC issued its final update.
The outbreak serves as another reminder that fresh produce — food Americans routinely put on their plates without a second thought — can become the vehicle for a major nationwide health emergency when contamination enters the supply chain.
For thousands of Americans this summer, a microscopic parasite hidden in ordinary iceberg lettuce resulted in weeks of illness.
For hundreds, it meant hospitalization.
And in Michigan, two cases ended in death.
