Largest US Cyclospora Outbreak Ends After Thousands Fall Ill

The largest reported outbreak of cyclospora infection in the United States has officially come to an end, according to health officials. The Centers for Disease Control and Prevention (CDC) announced on Friday that the outbreak, which spread across multiple states and sickened thousands of people, had significantly declined.

The outbreak involved cyclosporiasis, an intestinal illness caused by the microscopic parasite Cyclospora cayetanensis. The infection can cause prolonged and sometimes severe diarrhoea, along with other digestive symptoms.

According to the CDC, more than 12,000 people were affected in the outbreak that prompted the latest investigation. Two people died and hundreds required hospital treatment. Health officials in Michigan said both deaths involved people who had serious underlying medical conditions that may have been worsened by cyclosporiasis and dehydration.

What caused the outbreak?

Investigators have linked a significant portion of the outbreak to lettuce imported from Mexico. The lettuce was supplied by Taylor Farms, a major food supplier whose products are used by restaurants and other food businesses across the United States.

Taylor Farms voluntarily recalled certain lettuce sourced from central Mexico after the investigation identified the product as a possible source of contamination.

Taco Bell, one of the restaurant chains affected by the investigation, also removed lettuce supplied by the company from its menu.

Although contaminated lettuce has been strongly associated with many cases, health officials have stressed that not every infection reported during the period was connected to the same source.

The CDC continues to investigate how the parasite entered the food supply and how contamination occurred.

What is cyclospora?

Cyclospora is a microscopic parasite that can infect the digestive system when people consume food or water contaminated with the organism.

The resulting illness, known as cyclosporiasis, primarily affects the intestines. One of the most noticeable symptoms is frequent or severe watery diarrhoea.

Other symptoms can include abdominal cramps, bloating, nausea, fatigue, loss of appetite and weight loss. Some people may experience symptoms for weeks if the infection is not diagnosed and treated.

The illness can be particularly concerning when prolonged diarrhoea results in significant fluid loss. Dehydration can become dangerous, particularly for older adults, young children and people who already have serious medical conditions.

Despite the severity of some cases, the CDC says cyclosporiasis is generally not considered a life-threatening infection.

Thousands of cases reported across the country

CDC data indicate that nearly 20,000 confirmed cases of cyclosporiasis have been reported in the United States since 1 May. More than 1,000 hospitalisations have also been recorded during this period.

Cases have been reported in 49 states and Washington, DC.

The actual number of people who became ill is likely considerably higher because many infections may never be formally diagnosed or reported. People with diarrhoea may recover without visiting a doctor, while others may be diagnosed with a different gastrointestinal illness.

The unusually high number of reported infections made this outbreak particularly significant.

Before the current outbreak, 2019 had been the worst year on record for reported cyclospora infections in the United States, with approximately 4,700 cases.

The latest outbreak therefore represents a substantial increase compared with previous years.

Why food contamination can be difficult to trace

Identifying the source of a foodborne outbreak can be complicated because contaminated ingredients may be distributed across multiple states and used by numerous businesses.

Fresh produce can also pass through several stages before reaching consumers. An ingredient grown in one country may be processed, packaged, transported and distributed to restaurants or supermarkets in another.

In the case of cyclospora, tracing the source can be particularly challenging because symptoms may not appear immediately after exposure. This can make it difficult for people to remember what foods they consumed before becoming sick.

Investigators may therefore need to compare information from many patients, examine food distribution records and conduct laboratory testing before identifying a likely source.

What does the end of the outbreak mean?

The CDC's announcement that the outbreak is over does not necessarily mean that cyclospora infections have disappeared.

Instead, it means that the number of illnesses associated with the outbreak has fallen significantly and no longer meets the agency's criteria for an ongoing outbreak investigation.

People can still become infected with cyclospora through contaminated food or water. Cases unrelated to the specific outbreak may continue to occur.

The CDC has also said that its investigation into the cause of the outbreak is continuing.

This distinction is important because declaring an outbreak over does not mean that every possible source of contamination has been completely explained.

UK officials also monitoring the situation

The outbreak has attracted attention outside the United States as well.

UK health authorities have issued warnings following recent cases involving travellers who had returned from the United States. This highlights how foodborne and intestinal infections can cross borders through international travel.

Travellers who develop persistent diarrhoea after visiting an area where cyclospora infections are occurring may need to seek medical advice.

Healthcare professionals can use laboratory testing to help identify the parasite, since its symptoms can overlap with other gastrointestinal infections.

How can people reduce the risk?

Preventing cyclospora infections can be difficult because contamination is not always visible. Food may look, smell and taste normal even when harmful microorganisms or parasites are present.

General food safety measures remain important. Consumers should wash fresh produce under running water where appropriate, keep food preparation surfaces clean and avoid cross-contamination between raw and ready-to-eat foods.

However, washing produce does not necessarily eliminate every parasite. Following official recalls and public health warnings is therefore especially important.

People should also avoid consuming recalled products if they have been identified by health authorities.

When should you seek medical advice?

Persistent or severe diarrhoea should not be ignored, particularly when it is accompanied by signs of dehydration.

Symptoms such as extreme thirst, dizziness, weakness, reduced urination or confusion can indicate significant fluid loss and may require urgent medical attention.

Anyone who develops prolonged digestive symptoms after travelling or eating food associated with a public health warning should tell a healthcare professional about their recent food and travel history.

Treatment is available for cyclosporiasis, but the appropriate diagnosis and medication should be determined by a healthcare professional.

A major public health warning

The end of the latest US cyclospora outbreak offers some reassurance, but the scale of the incident demonstrates the challenges involved in protecting the food supply.

With thousands of confirmed infections and more than 1,000 hospitalisations reported nationally, the outbreak was far larger than previous major years for cyclospora.

The CDC's decision to continue investigating the source also shows that ending an outbreak does not necessarily end the search for answers.

For consumers, the episode is another reminder of the importance of paying attention to food recalls and public health announcements, particularly when illnesses are linked to widely distributed fresh produce.

While cyclospora infections are usually treatable and deaths are uncommon, severe diarrhoea can lead to dehydration and serious complications, especially among vulnerable people.

The latest outbreak may now be considered over, but health authorities will continue monitoring new infections and investigating how contamination occurred to help prevent another large-scale outbreak in the future.

Sources

• U.S. Centers for Disease Control and Prevention (CDC), information and outbreak updates concerning cyclospora and cyclosporiasis.
• BBC News, report on the US cyclospora outbreak, published 12 September 2026.
• Michigan health officials, information concerning the two reported deaths associated with the outbreak.
• Taylor Farms, voluntary recall information concerning lettuce sourced from central Mexico.

Disclaimer

This article is intended for general informational and educational purposes only. It is not medical advice and should not be used as a substitute for consultation with a qualified healthcare professional. Symptoms can have many possible causes. Anyone experiencing persistent, severe or concerning symptoms should seek appropriate medical advice. Public health information can change as investigations develop, so readers should check current guidance from official health authorities for the latest information.