Summer of Cyclospora!
This summer, the CDC reported a surge in the number of cyclosporiasis cases across the US. Read the following article to learn more about Cyclospora, the "explosive diarrhea" parasite causing the outbreak, and how it spreads. Afterwards, download our FREE Cyclosporiasis Outbreak Resource (attached as a PDF below) to practice reading and interpreting graphs with real world data in your classroom!
Fruits and vegetables are an important part of a healthy, balanced diet. The produce that you eat is grown year-round, all over the world, and then harvested, packaged, and shipped right to your local grocery store! During the long journey from the ground to your stomach, produce can come in contact with contaminated water or soil that carries microscopic organisms. These microorganisms can hitch a ride on the leaves and skin of fruits and vegetables and end up in our stomachs without us even knowing.
Many of the microorganisms on produce are completely harmless, but there are a few types that can make us sick. Foodborne illnesses are commonly caused by harmful bacteria like E. coli and Salmonella. When food is left out for too long or not cooked properly, these bacteria can quickly multiply or produce toxins that, when ingested, cause severe gastrointestinal issues.
Food poisoning can also be caused by parasites. A parasite is any organism that requires a host organism to live on or inside. Parasites cause harm to their hosts by stealing nutrients, damaging tissues, or triggering immune responses (much like a virus). Some parasites only need one host for their whole life, while other parasites need different hosts at different stages of their life cycle.1
Cyclospora cayetanensis is one type of microscopic, single-celled parasite that, when ingested, causes a gastrointestinal illness called cyclosporiasis.
The most common symptoms of cyclosporiasis are watery diarrhea and intense stomach pain that can last for months if left untreated.
Unlike other foodborne illnesses, such as norovirus, cyclosporiasis does not spread directly from person to person. After an infected person passes the parasite in their feces, Cyclospora must remain in the environment for 1–2 weeks before it becomes infectious. During this time, the parasite is protected inside an oocyst, a tiny, tough shell that helps it survive outside the body. Oocysts can survive in contaminated soil or irrigation water and may stick to fresh fruits and vegetables. If a person eats contaminated produce or drinks contaminated water, they can become infected and the cycle begins again.2
An outbreak is a sudden rise in the number of cases of an illness within a community or region that exceeds what is normally expected. According to the CDC, there over 18,000 lab documented cases of cyclosporiasis were reported across the US, making it one of the largest food-borne illness outbreaks in recent years.3 The FDA has linked a large portion of the outbreak to shredded iceberg lettuce grown in Mexico by Taylor Farms. Taylor Farms issued a voluntary recall of their product on July 17, 2026.
Although cyclosporiasis can cause unpleasant intestinal symptoms, the infection can usually be treated with an antibiotic called trimethoprim-sulfamethoxazole. Preventing infection is also an important part of protecting public health. People can reduce their risk by washing their hands, rinsing fresh produce with clean water, and following safe food preparation practices. Cooking certain foods can also help reduce the risk of illness by destroying some harmful organisms.4
Preventing cyclosporiasis outbreaks also requires safety measures before food gets to your grocery store. Farmers follow strict sanitation practices to reduce the chance that produce becomes contaminated. One important area of study for agricultural scientists is the use of water. Wastewater used for irrigation can provide crops with water and nutrients, but if it is not properly managed, it may also contain harmful microorganisms, including parasites such as Cyclospora. Research has shown that properly treating wastewater for crop irrigation can reduce many public health risks, although some treatment methods may affect crop productivity or influence the spread of antibiotic-resistant microorganisms.5 Furthermore, many countries across the globe that grow our produce from have different regulations regarding water treatment or lack the infrastructure and resources to easily treat irrigation water.
Because of this, preventing outbreaks requires multiple layers of protection, including safe water practices, careful monitoring of irrigation systems, proper sanitation, and safe handling of fresh produce from farms to your kitchen.
Glossary:
Microorganisms- Living organisms that are so small that can only be seen under a microscope
Gastrointestinal- Relating to the digestive system, especially the stomach and intestines
Parasite- Any living organism that lives on or in another living organism for nutrients or protection and causes harm to that organism
Host- The organism that a parasite lives in or on
Symptoms- The physical changes you feel when you are sick or hurt
Cyclospora- The common name for the single-celled parasite (Cyclospora cayetanensis) that can make humans sick if ingested
Cyclosporiasis- An intestinal illness caused by the cyclospora parasite
Oocyst- (OH-uh-sist) A hard, shell-like structure that protects a parasite from harsh environments after it has been shed from its host
Outbreak- A sudden rise in the number of cases of an illness within a community or region that exceeds what is normally expected
Antibiotics- The group of medicines that treat bacterial infections by killing bacteria or preventing them from growing, some antibiotics can also treat infections caused by parasites
Free Classroom Resource: Cyclospora Reading & Graph Activity
This summer's Cyclosporiasis outbreak is a great opportunity to connect science, health, and graphing with a real-world event. Students can learn about food safety, how foodborne illnesses spread, and how scientists investigate outbreaks while practicing graph interpretation skills with our FREE resource below!
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