According to the Centers for Disease Control (CDC), 41 affected U.S. states have produced more than 4,000 confirmed cases with an estimated 7,000 or more unconfirmed cases to date.

Michigan is believed to be the most affected state, with more than 8,000 cases reported by the Michigan Department of Health and Human Services (MDHHS) as of July 24. Michigan typically has around 50 cases each year. Usually, the presence of cyclospora risk continues through the end of August.

Cyclosporiasis is an intestinal illness caused by ingestion of microscopic cyclospora parasites from water or food that has been contaminated with germs from feces. It may occur when contaminated water is used to grow or wash produce. There is no evidence that it spreads from person to person.

In the summer months, cyclospora can be especially prominent because the organism requires warm, humid conditions to mature and become infectious after leaving the human body.

“Cyclospora is not a new foodborne illness,” Michigan State University Extension food safety expert Wade Syers said. “The U.S. has experienced numerous produce-associated outbreaks over the years. Fresh produce such as leafy greens, herbs, and other fruits and vegetables have been linked to Cyclospora outbreaks in the past.”

“What makes this outbreak notable is the large number of reported illnesses and the extensive geographic area affected,” Syers added.

Ingham County is among the Michigan counties believed to be the most affected by the cyclospora outbreak, with nearly 700 cases reported by MDHHS.

Local officials at the Ingham County Health Department (ICHD) are working diligently to investigate all laboratory-confirmed Cyclospora cases in the area.

ICHD Deputy Health Officer Anne Barna said that the influx and backlog of cases in recent days have led to the department’s decision to focus efforts on the most recent cases first, since those cases are most likely to still be causing people to get cyclospora.

Barna explained that positive test results are delivered to them in a statewide electronic system, which they use to follow up with patients by survey or phone call.

“The purpose of following up with them is to do an investigation. The investigation is the way that we understand what their symptoms have been, as well as what they've eaten or places they have been to eat or places that they have bought food,” Barna said. “That makes it easier when you're looking across the state to understand patterns. That's what our epidemiologists are looking for: to understand what's happening: Is this restaurant a potential source? Is this product bought at this store a potential source, et cetera?”

That follow-up procedure is just one way Michigan experts are trying to track the source of the outbreak. Because some people may have the parasite for multiple weeks before showing symptoms, cyclospora can be difficult to track.

MSU fisheries and wildlife professor and microbiology expert Nishita D’Souza is working to track Cyclospora through wastewater. Her team already had procedures in place for monitoring other bacterial, fungal, or viral targets, such as COVID-19, but now they’re trying to adapt them for parasitic targets like cyclospora.

“The real goal of what we are trying to do with wastewater is to see if we can understand the burden of disease in the community,” D’Souza said. “So ideally, before an outbreak, if we were monitoring, we would be able to see when that onset came in, if people were shedding it.”

During an outbreak, that information can help local health departments figure out how many infected people there are, which regions are higher risk, where they should prioritize clinical testing or resources and when the outbreak is dying down.

The FDA initially linked the outbreak to Taco Bell lettuce on July 16 and named Taylor Farms de Mexico as the source on July 17. Taylor Farms issued a voluntary recall of all iceberg lettuce sourced from Mexico in the U.S. market, including a recall notice for bagged lettuce products they sold at Walmart, also on July 17. Additionally, Taco Bell indicated they are no longer using lettuce from Taylor Farms de Mexico as of July 17.

Then on July 19, the FDA walked back on its findings, claiming that it was a false positive test result.

However, Taylor Farms’ recall still stands, and the traceback of thousands of cases to that lettuce still stands, which is based on epidemiological information collected by the CDC.

According to reporting by The New York Times, Taylor Farms company executives met with White House and FDA officials on the evening of July 16 as the company sought to distance itself from the outbreak.

Now, the FDA announced an additional separate cyclospora outbreak that is affecting at least 72 people nationwide. There are also four more separate cyclospora outbreaks that are affecting at least 38 people total nationwide. The FDA has not yet identified a source of any of these outbreaks.

The FDA and state partners are actively investigating the source and scope of the contamination, including tracking any additional implicated brands or distribution channels, according to their website.

A full list of affected stores and recalled products and their identifying information can be found on the FDA Taylor Farms safety alert webpage. A full list of current cyclospora outbreaks and their investigation status can be found on the FDA Investigations of Foodborne Illness Outbreaks webpage.

The unprecedented outbreak comes months after the Trump administration cut state and federal health programs and departments that dealt with cyclospora, contributing to the lag in response.

Although the first illnesses began in mid-May, the CDC didn’t notify the public or healthcare providers about the outbreak until July 14. The Michigan Department of Health and Human Services (MDHHS) warned the public of the outbreak two weeks earlier.

Barna said that while local agencies like ICHD are trying to communicate statewide guidelines to consumers, the federal response has confused many about how they should react.

“In terms of the changes at the federal level, what I have been concerned with and what I have observed is the communication challenges of this outbreak have been really significant,” Barna said. “The issuing of a recall, and then the clarification that they had a false positive, and then the clarification that the epidemiological evidence still points to this bagged lettuce product from this manufacturer — it's just been very confusing, and it's been very difficult to figure out what to message to our community.”

Barna said that ICHD wants to give clear, understandable information to the community so they can take appropriate actions to stay safe. She added that the federal government has made it difficult to do that with its response.

According to the CDC data project, the CDC has seen about a 25% workforce reduction and an 80% leadership reduction since Feb. 2025. For example, the CDC laboratory specializing in cyclospora has been reduced from 11 people to three.

In March 2025, the Trump administration cut $12 billion in federal public health funding and grants, including disease monitoring and outbreak investigation. After the cuts in Michigan, 123 local health department staff were lost, as well as 23 state bureau of infectious diseases staff.

As of July 1, 2025, the Trump administration scaled down the Foodborne Diseases Active Surveillance Network (FoodNet), a surveillance system that had been in place for three decades. FoodNet is a collaboration between the CDC, the FDA, the Department of Agriculture, and 10 state health departments.

Before this change, FoodNet was responsible for tracking infections caused by eight pathogens that can cause foodborne illness, including cyclosporiasis. Now, it’s responsible for just two pathogens: salmonella and shiga toxin-producing E. coli (STEC), while reporting on others is optional.

Additionally, last summer, as part of DOGE cuts, the CDC’s Division of Parasitic Diseases and Malaria was quietly disbanded. The division helped track, test, research, consult on and provide treatment for diseases including cyclospora.

Fruits and veggies tied to past cyclosporiasis outbreaks in the U.S. include bagged salads and salad mixes, basil, cilantro, parsley, mesclun lettuce, raspberries, snow peas and sweet peas.

Barna and D’Souza echoed that one may want to take extra precautions if in a vulnerable group, such as immunocompromised or pregnant. Individuals may want to opt for frozen or canned produce rather than fresh or pre-packaged. The only sure-fire way to completely kill the parasite is to cook your food to at least 158°F.

“For Michigan consumers, rinsing fresh produce under running water, using a produce brush where appropriate, and keeping raw produce separate from other foods are important food safety practices,” Syers said. “Consumers concerned about risk may want to consider purchasing whole heads of lettuce, removing the outer leaves, and preparing them at home rather than buying pre-cut or bagged salad products.”

Syers also said that people should follow recall notices and public health advisories to stay informed and seek medical attention if they develop prolonged watery diarrhea consistent with cyclospora infection.

For more information about how to avoid the parasite, visit the FDA Cyclospora Information webpage.

Some of the symptoms associated with cyclospora include frequent bouts of watery diarrhea, loss of appetite and weight, nausea, fatigue, low-grade fever, cramping and bloating that may last weeks.

If not treated, the illness may lead to dehydration and severe complications that may require higher levels of care.

“Anyone experiencing gastrointestinal illness, such as sudden and ongoing diarrhea, should contact their health care provider and their local health department,” MDHHS said in a statement last week.

Call the MSU Food Safety Hotline 1-877-643-9882 for any questions about food safety, Mon-Fri 9:00 a.m. to 5:00 p.m.