|
Getting your Trinity Audio player ready...
|
Presented by
This content is made possible by our sponsor. It is not written by and does not necessarily reflect the views of the editorial staff.
What to know about cyclosporiasis
The latest foodborne illness goes by the name cyclosporiasis (sigh-klo-spor-eye-uh-sis). Since the first known case in Michigan in June 2026, the parasitic disease has stricken thousands of people.
What are the symptoms of cyclosporiasis?
The signature symptom of cyclosporiasis is copious, watery diarrhea, which can lead to dangerous dehydration and electrolyte imbalance, posing kidney damage risks and requiring hospitalization, with some patients experiencing as much as 10% weight loss. Other common symptoms include nausea, loss of appetite, cramping, bloating, gas, fatigue, and weight loss.
“Cyclosporiasis is a potentially very serious infection, especially for people who are young, elderly, immune-impaired, or sick for other reasons,” said David Relman, MD, the Thomas C. and Joan M. Merigan Professor of Medicine and professor of microbiology and immunology at Stanford Medicine. “Even for healthy people, cyclosporiasis can be pretty debilitating.” Relman’s work characterizing the parasitic organism that causes cyclosporiasis helped revolutionize diagnosis of this infection and outbreak tracing.
What causes cyclosporiasis?
Nearly all foodborne illness in the U.S. stems from bacterial and viral infections. Cyclosporiasis, however, arises from a single-celled parasite called Cyclospora cayetanensis, which is more closely related to animals than to bacteria and viruses.
How do you get infected with cyclospora?
Cyclospora enters our bodies when we eat food, usually fresh produce, that is contaminated with the microbe. Among the likeliest foods to harbor cyclospora are leafy greens, fruits such as raspberries, and herbs, including basil and cilantro. The parasite is not endemic to the United States, and outbreaks are usually connected to food imported from other countries – for instance, in Central America. The lifecycle of Cyclospora cayetanensis requires that it enter a human digestive tract to grow and reproduce. The parasite reenters the environment and contaminates crops through traces of human feces that end up in water supplies for irrigation.
What is the incubation period?
The typical time it takes from consumption of sporulated cyclospora oocysts to active disease is about a week, though this so-called incubation period varies from patient to patient and may depend on how many cyclospora oocysts they ingest. “The incubation period is actually highly variable,” Relman said. “People often cite a week, but it can be quicker, especially if you get a huge infectious dose. The common understanding is that the incubation period can vary from two days to two weeks.”
How do you diagnose cyclosporiasis?
Definitive diagnosis requires a stool sample test. The conventional ova and parasite test, however, won’t suffice. Instead, quick diagnosis is usually done in hospitals or in outpatient clinical settings through modern molecular testing, which looks for the DNA or the RNA of infectious agents. Research by Relman, who is also a senior fellow at the Freeman Spogli Institute for International Studies at Stanford University, in the early to mid-1990s pioneered the use of PCR for classifying and detecting cyclospora and other infectious agents.
How do you treat cyclosporiasis?
Thankfully, if properly diagnosed, cyclosporiasis is easily treatable with a seven- to 10-day course of the antibiotic trimethoprim-sulfamethoxazole, which disrupts the microbe’s ability to produce the folic acid needed to replicate itself. Most people start feeling better in a few days. Fluid replacement is also an integral part of successful treatment and recovery.
Does washing food get rid of cyclospora?
Washing in cold water for at least a minute absolutely helps. But because cysts can still get stuck in nooks and crannies of fruits and veggies, a safer alternative can be cooking the food in question, as heat kills the parasite. “If you don’t have a strong need to immediately consume suspicious produce in a raw form and have the option of cooking it, why not?” Relman said.
Does buying locally grown produce reduce risk of exposure to cyclospora?
Yes. Cyclospora usually comes to the U.S. through imported foods. Relman pointed out that lettuce is “often mixed from all over the place and then sorted into prepackaged bags and sold widely … that’s going to increase your chances [of exposure].” A good alternative is to buy produce at a local farmer’s market. “If you’re able to purchase produce locally from a known vendor who’s not sourcing it from all over the place but rather from one local farm, that’s probably a safer bet,” Relman said.
Read the full story as originally published by Stanford Medicine.
Do you live close to campus? Sign up now to receive a new weekly email designed specifically for our neighbors. Starting this fall, we’ll let you know about events and activities on campus and deliver Stanford news, research, and expert insights right to your inbox.
Stanford is committed to supporting our community by advancing interdisciplinary teaching and research, providing world-class medical care, and extending knowledge and discovery to our neighbors. Stanford invites its neighbors to enjoy its open lands and participate in learning, athletic, and arts events on campus.
Learn more about Stanford University
