US parasitic illness cases surge to nearly four times annual average, linked to contaminated lettuce

The number of cases of a parasitic illness that causes explosive diarrhea has risen to levels nearly four times the average annual total in the United States, federal data revealed Tuesday.

There have been 4,173 confirmed cases of cyclosporiasis across 41 states, the Centers for Disease Control and Prevention said. An additional 7,400 cases reported to the agency have yet to be confirmed.

Michigan state health officials have reported 6,571 cases, the most in the country. Cases there have been tied to contaminated lettuce. Cyclosporiasis spreads from exposure to produce contaminated with the cyclospora parasite.

In a typical year, there are only around 40-50 cases in Michigan and 1,000 infections across the U.S., according to the American Medical Association.

Infections are not life-threatening but they are particularly unpleasant. Cases often lead to vomiting, body aches, fever, fatigue and gastrointestinal distress that can leave patients dehydrated. “You’re barely able to make it to the toilet,” Dr. Alejandro Macías, an epidemiologist and physician at the University of Guanajuato in central Mexico, told The New York Times Wednesday.

Health Secretary Robert F. Kennedy Jr. said Tuesday that the outbreaks were “under control,” despite ballooning case numbers.

"We have done extensive forensics, epidemiological forensics and we have identified the source of the outbreak. We, and the companies that are involved, have implemented a recall," he told reporters during a news conference.

A voluntary recall of iceberg lettuce, sourced from central Mexico, was issued by California’s Taylor Farms last week based on an investigation from the Food and Drug Administration.

That investigation led to some confusion earlier this week after the FDA announced a “false positive test” - but insisted that reevaluating the sample did not alter data supporting an advisory that led to the Taylor Farms recall.

“To clarify, this false-positive lab sample DOES NOT change the basis for FDA’s ongoing outbreak investigation or the overwhelming epidemiological data supporting the current voluntary recall by Taylor Farms,” the agency wrote in a social media post.

To date, no positive tests have been reported from any source and the source of outbreaks nationwide remains under investigation, the agency says.

Unfortunately, case counts aren’t likely to slow any time soon. They may rise through August, the CDC says.

That’s partly due to how cyclosporiasis symptoms develop. Signs of infection usually appear a week after consuming the contaminated food or water but can take as little as two days or up to two weeks to appear, according to New York health officials.

And some people may not experience any symptoms at all.

The best way to reduce exposure to cyclospora is to avoid any potentially-contaminated sources, as well as to cook and thoroughly clean food, the CDC says. Heating food to 158 degrees Fahrenheit kills cyclospora.