Health

When will cyclospora outbreak be over? Expert predictions revealed

Newsweek · Jul 21, 2026 18:32 · 5 min read

Close up of washing organic lettuce leaves for fresh salad preparation

A "best-case scenario" could still see the cyclospora outbreak lasting into August, one expert said.

As health officials continue investigating a multistate cyclospora outbreak linked to recalled iceberg lettuce, many Americans may be wondering how long it will take before the outbreak is over. Experts say that reported case numbers could continue rising even after contaminated products have been removed from store shelves.

What to Know About Cyclospora Outbreak in U.S.

A cyclospora outbreak has spread across the United States this summer, with the Centers for Disease Control and Prevention (CDC) reporting 1,645 confirmed cases and 141 hospitalizations. However, state health officials have reported significantly higher totals, including more than 6,000 cases in Michigan, the state hardest hit by the outbreak.

On Tuesday, Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. said the national outbreak is now “under control,” stating that officials have identified the source and removed affected products from the market.

On July 17, Taylor Farms de Mexico recalled several shredded iceberg lettuce products linked to the investigation. The company later said the Food and Drug Administration (FDA) informed it that an initial test result was a “false positive,” though federal investigators continue to identify Taylor Farms lettuce as the likely source of the outbreak.

When will cyclospora outbreak be over? Expert predictions revealed — Stock image: A person washes lettuce leaves.

When Will Cyclospora Outbreak End?

While the recall is an important step toward ending the outbreak, experts told Newsweek that cases are likely to continue emerging for weeks.

“An outbreak like this ends in stages, not all at once,” Dr. Tyler Evans, founder and CEO of Wellness Equity Alliance, told Newsweek. “On July 17, Taylor Farms de Mexico recalled all iceberg lettuce sourced from central Mexico, which removed the identified source from stores and restaurants. When you pull the contaminated product, new exposures start to fall.”

That does not mean infections stop immediately, however. Cyclospora infections often take time to appear after someone consumes contaminated food. According to Evans, people can develop symptoms anywhere from two days to two weeks after exposure.

“Cases will keep being reported for a few weeks after the last contaminated lettuce is gone,” he said.

The delay means public health data may continue to show rising case counts even if the outbreak has already peaked in terms of new exposures. Additional reports can also emerge because diagnosing cyclospora is not always straightforward. Patients may undergo specialized testing and, in some cases, provide multiple stool samples before the parasite is identified.

As long as the outbreak has a single source, there should soon be an improvement in case numbers, Johns Hopkins University professor Cindy Spears told Newsweek. However, if case numbers don’t improve, that implies “there is more than one contaminated source for this large outbreak—which can occur.”

“Locally produced veggies should be unaffected and if one can be certain that the bag of lettuce is not linked to Taylor Farms, the lettuce may be fine,” Sears said. “Even though I saw an investigator purport that most lettuce is safe, I feel more cautious given how food is distributed in the United States and sources relabeled on the packages—at least that is my understanding from evaluating prior outbreaks and food sources.”

Bill Hanage, an epidemiologist at Harvard T.H. Chan School of Public Health, said outbreaks linked to a specific food source typically come to an end when that source is removed from circulation. Hanage said the ongoing cyclospora outbreak will last into August in the best-case scenario.

“Outbreaks like this come to an end when the contamination of the food supply is ended,” Hanage told Newsweek. “That can happen because the source is identified and removed, or because all the contaminated food gets eaten.”

Weather may also influence how the outbreak evolves in the coming weeks and months. Unlike many bacteria and viruses, cyclospora is a parasite that requires time in the environment before it becomes infectious.

“In the case of this parasite, the weather also plays a role,” Hanage said. “Because it needs days to weeks of warm temperatures to mature and become infectious, once we hit cooler temperatures that will make a difference and case counts should decline. At least for some of the country.”

Cyclospora outbreaks in the United States are often associated with warmer months, when imported produce and favorable environmental conditions can contribute to transmission. Experts caution, however, that weather alone will not immediately halt an outbreak if contaminated food is already in circulation. However, for consumers, health specialists stress that the outbreak should not be a reason to avoid fresh produce altogether.

“For the average healthy person, there is no reason to stop eating fruits and vegetables,” Evans said. “Produce belongs in a healthy diet, and the risk right now is narrow.”

He advises consumers to wash fresh produce under running water before eating it, while noting that washing alone cannot fully eliminate cyclospora contamination. That is why identifying and removing contaminated products remains the most effective way to stop an outbreak.

People who develop persistent gastrointestinal symptoms should consider seeking medical care and asking to be tested for cyclospora, particularly if diarrhea lasts for several days or returns after appearing to improve.

“The infection is very treatable with the right antibiotic once it is identified, but it gets missed when no one thinks to look for it,” Evans said.

For now, experts say the outbreak’s trajectory will depend largely on whether the recall successfully removes contaminated lettuce from the food supply and whether investigators identify any additional contaminated products linked to the outbreak. Even so, reported infections are expected to lag behind those efforts because cyclospora can take days or even weeks to cause symptoms, meaning case counts may continue to rise for some time after the source has been addressed.

Where Did Cyclospora Come From?

Cyclospora is a microscopic parasite called Cyclospora cayetanensis that spreads when people consume food or water contaminated with human feces containing the organism. In the United States, outbreaks have most often been linked to fresh produce such as leafy greens, herbs, berries and other foods that are eaten raw. Because the parasite needs time to mature in the environment before it becomes infectious, direct person-to-person transmission is considered unlikely.

How Do You Know If You Have Cyclospora?

The hallmark symptom of cyclosporiasis is explosive diarrhea. Other common signs include loss of appetite, weight loss, stomach cramps, bloating, gas, nausea and fatigue. Because the illness can resemble other gastrointestinal infections, a diagnosis usually requires a specialized stool test, and some patients may need to submit multiple samples collected on different days because the parasite can be difficult to detect. Without treatment, symptoms can last for weeks and may improve before returning again.