More than 200 people have been infected by an intestinal parasite after reportedly eating vegetables from Fresh Del Monte Produce vegetable trays, the federal authorities said.
The Centers for Disease Control and Prevention reported there were 212 cases of the infection, cyclosporiasis, in Iowa, Michigan, Minnesota and Wisconsin as of Thursday.
Those infected reported eating from the prepackaged vegetable trays, which included broccoli, cauliflower, carrots and dill dip. Most of the trays were bought from Kwik Trip or Kwik Star convenience stores in those states, according to the C.D.C.
Del Monte and Kwik Trip could not be immediately reached for comment on Saturday.
Outbreaks of cyclosporiasis in the United States have been linked to imported fresh produce contaminated with a microscopic parasite called Cyclospora cayetanensis. The infection first gained prominence in the United States during an outbreak in the mid-1990s, and has shown up nearly every year since, the C.D.C. said.
The infection can cause a host of stomach-related illnesses, fever and fatigue, and symptoms typically show up one week after the contaminated food was consumed. That means that the number of cases could continue to climb as more people start reporting their illnesses.
It is also one of the main reasons that cyclosporiasis is so difficult to understand, said Michael T. Osterholm, a professor at the University of Minnesota and an international food-borne disease expert.
“By the time cases are detected, the product is long gone,” he said. “It’s very hard to trace back.”
He said he suspected the number of cases was much higher than the 212 confirmed so far by health officials.
In 1996, more than 1,000 people were sickened by cyclospora parasites, catching health officials off guard and prompting them to ramp up food testing to try to trace the source of the outbreak.
Since then, cyclospora-related outbreaks have been linked to raspberries, basil, snow peas, sugar snap peas, cilantro and cabbage. In 2013, more than 600 cases of cyclosporiasis in two dozen states were tied to a salad mix.
Dr. Osterholm, director of the university’s Center for Infectious Disease Research and Policy, said that the prevalence of the infection had been tied to an increase in imported produce from South and Central America and Mexico, but that the source of the infection remained unclear.
According to the C.D.C., the parasite most likely got on the produce through feces. But Dr. Osterholm said it still is not known exactly how and why the produce gets contaminated.
“We have to find out what it is,” he said. “Is it wildlife?”
The outbreaks typically happen in May and June, which could indicate that they are tied to an animal’s life cycle.
“We’re not any farther along in preventing them today than we were back then,” he said.
It’s unclear which vegetable in the trays is behind the current outbreak.
Last month, Del Monte recalled three of its products in stores in six states in the Midwest: six-, 12- and 28-ounce vegetable trays that had broccoli, cauliflower, celery, carrots and dill dip. All those products had a “best if enjoyed by” date of June 17.
The recalls affected Illinois and Indiana, in addition to the four states where the infections have been reported. The C.D.C. encouraged people to throw away any of the recalled vegetable trays.
The federal agencies investigating the outbreak, the C.D.C. and the Food and Drug Administration, are investigating on multiple fronts, analyzing when and where people got sick, and which grocery stores or restaurants people might have patronized.
The process can be challenging. An investigation last year into more than 1,000 cyclosporiasis cases could not identify how the infection was spread or whether it was all part of one outbreak or several smaller outbreaks.
Texas said on Monday it was separately investigating 56 cases of cyclosporiasis that health officials there had found since the beginning of May. It was unclear if those cases were connected to the ones reported in the Midwest.
