U.S. health officials are investigating a separate cluster of Cyclospora infections after dozens of people became ill, adding another layer to a summer that has already seen an unusually large number of foodborne illness cases across the country.

The Food and Drug Administration identified the new cluster in July after 72 people were linked to infections caused by Cyclospora, a microscopic parasite that can trigger prolonged gastrointestinal illness. Unlike a larger Cyclospora outbreak connected to recalled iceberg lettuce, investigators have not identified the source of this particular cluster.

The investigation highlights the difficulty of tracing foodborne illnesses when people may have eaten the same contaminated ingredient at different locations and at different times.

A Second Investigation Adds to a Growing Outbreak Picture

Cyclospora has become an unusually prominent public health concern in the United States this year.

According to the Centers for Disease Control and Prevention, 15,716 laboratory-confirmed cases of domestically acquired cyclosporiasis had been reported between May 1 and August 17. The cases were spread across 47 states, the District of Columbia and Puerto Rico. The agency also said more than 11,800 additional cases may require further investigation.

A large portion of the increase is connected to a separate multistate outbreak involving iceberg lettuce processed by Taylor Farms de Mexico. CDC investigators have concluded that contaminated lettuce made people sick, and the company recalled iceberg lettuce sourced from central Mexico in July. The recalled products are no longer expected to be on store shelves because their best-by dates have passed.

The newly identified 72-person cluster is different. Officials have not connected it to the recalled lettuce, and the search for its source remains underway.

Why Finding the Source Can Take Time

Cyclospora presents a particular challenge for investigators because symptoms may not appear immediately after exposure.

The parasite can cause diarrhea, stomach cramps, nausea, fatigue and other gastrointestinal symptoms. People can become infected by consuming food or water contaminated with the parasite, making traceback investigations dependent on detailed interviews, laboratory testing and information about where people ate or purchased food.

The CDC says recent cases may take weeks to identify as part of an outbreak. Some people also recover without seeking medical attention, meaning the number of actual infections can be higher than official case counts.

For health officials, identifying a common source is important because it can allow authorities to remove contaminated products from circulation and prevent additional infections.

What Consumers Should Know

The investigation does not mean Americans should avoid fresh produce altogether. Instead, health authorities continue to emphasize following specific food recalls and public health warnings.

The CDC is investigating several Cyclospora clusters in addition to the large lettuce-related outbreak. At present, the agency says some of these clusters have no confirmed source.

The broader outbreak has also demonstrated how quickly a food safety problem can affect consumers, restaurants and food suppliers when a contaminated ingredient moves through a large distribution network.

For now, investigators are working to determine what links the 72 illnesses and whether a common food, ingredient or other exposure can explain the infections.

Until that answer emerges, the case remains another reminder of how much of food safety happens behind the scenes, from tracing products through supply chains to identifying patterns in illnesses that may initially appear unrelated.