The Cyclospora Outbreak, By the Numbers

The cyclosporiasis outbreak that gripped the United States this summer has officially concluded, according to the Centers for Disease Control and Prevention (CDC), which announced the end on Friday. The outbreak was the largest recorded case of cyclosporiasis in the nation's history. Individuals contract the parasite by consuming contaminated food or water; in the U.S., fresh produce has often been implicated in such outbreaks.

Symptoms of cyclosporiasis can range from mild to severe, with some individuals showing no signs at all. However, those who do fall ill may experience "explosive" bowel movements. Health officials first announced an investigation into an outbreak of these infections in multiple states in July, which was later traced back to contaminated processed iceberg lettuce from Taylor Farms de Mexico.

The company subsequently recalled all its iceberg lettuce products sourced from central Mexico, stating it was a precautionary measure.

The CDC reported on Friday that the number of recent cyclosporiasis cases linked to this summer's outbreak had significantly dropped. While over 1,000 cases were being reported in a single day at the outbreak's peak, in August, the number had dwindled to fewer than two cases daily. The CDC emphasized that there was no longer any risk of people getting sick from this source, as the best-by dates for all products linked to the outbreak had passed.

However, the Food and Drug Administration is still conducting its investigation to ascertain how the lettuce product associated with the outbreak this summer became contaminated with Cyclospora cayetanensis.

The impact of the cyclosporiasis outbreak was substantial. The CDC confirmed that two individuals in Michigan died from cyclosporiasis during the summer outbreak. Both had significant underlying health conditions that may have contributed to their demise. It's important to note that cyclosporiasis rarely proves fatal; most individuals without such conditions usually recover even without treatment.

The CDC reported that a total of 12,883 people across the country became ill from the parasite during this summer's outbreak, though the agency noted that the actual number is likely higher due to many people recovering without seeking medical attention and therefore not being tested for the parasite. Of these confirmed cases, 570 individuals were hospitalized.

In a typical year, the U.S. sees only a few thousand cases of cyclosporiasis, with a five-year average between 2018-2022 of just 3,285 cases, according to data from the Colorado Department of Public Health & Environment. On average, less than 200 individuals were hospitalized each year. The outbreak affected 21 states, with Michigan, Ohio, and Missouri among the hardest-hit, reporting over 5,700, 2,871, and 1,071 cases respectively.

Other states such as Indiana, Kentucky, Kansas, Nebraska, Illinois, Pennsylvania, and Oklahoma also saw case numbers in the triple digits.