The Wyoming Department of Health has confirmed three cases in 2026 of cyclosporiasis, or “explosive diarrhea”, according to Surveillance Epidemiologist Matt Peterson.
The illness is caused by the microscopic parasite Cyclospora cayetanensis, which commonly triggers profuse watery diarrhea, severe cramping, bloating, nausea, fatigue, loss of appetite, and weight loss.
The Centers for Disease Control and Prevention says symptoms typically begin two days to two weeks after a person consumes contaminated food or water, making it difficult for many patients to remember exactly what they ate before becoming sick.
Two Wyoming patients likely contracted the parasite while traveling to countries where Cyclospora is endemic, Peterson told Cowboy State Daily.
The third patient, however, had no history of international travel.
The department did not identify the locations of the affected individuals.
The CDC is investigating a growing number of Cyclospora infections across the United States while working with state health departments and the U.S. Food and Drug Administration to identify the contaminated food responsible.
"At this time, we do not know if that case is related to any existing cluster or outbreak, but we are continuing to investigate the possibility," Peterson said.
Weeks In The Bathroom
Peterson said anyone experiencing prolonged watery diarrhea, especially if symptoms disappear and later return, should contact a physician and ask about testing.
Without treatment, cyclosporiasis can linger for weeks or even months, sometimes improving just enough to make people think they're recovering before roaring back with another round of illness.
Unlike viruses such as norovirus, Cyclospora generally does not spread directly from one sick person to another.
The CDC notes the parasite isn't infectious when it leaves a person's body. Instead, it must spend days to weeks maturing in the environment before it can infect someone else, making person-to-person transmission extremely uncommon.
Diagnosing the illness can also be challenging. Routine stool tests don't always detect Cyclospora, and physicians often must order specialized testing if they suspect the parasite.
Nearly all U.S. infections are linked to contaminated food or water.
What's Causing It?
Health officials still don't know exactly what's fueling this summer's outbreak.
Investigators with the CDC, FDA and state health departments are interviewing patients about everything they ate in the weeks before becoming ill, searching for common ingredients that could reveal the source. Because symptoms might not appear for up to two weeks, tracing the outbreak has proven especially difficult.
Past U.S. outbreaks have been linked to fresh produce, including cilantro, basil, raspberries, lettuce, mesclun greens and snow peas.
The FDA says washing produce helps remove dirt and many germs but might not completely remove Cyclospora. The parasite can cling tightly to fresh fruits and vegetables, making cooking the most effective way to eliminate it.
That makes Wyoming vulnerable even though the parasite isn't naturally found here.
"Because Cyclospora is not endemic here, imported fresh produce is always the most likely vehicle," Peterson said.
He said cooking food to an internal temperature of 158 degrees Fahrenheit will kill or inactivate the parasite. Choosing locally grown produce when available might also reduce the risk.
Peterson said Wyoming residents aren't insulated simply because they live far from major farming regions. Grocery stores across the state receive produce through the same national distribution networks that supply much of the country.
Significant Growth
The Wyoming cases come as public health officials investigate what has become one of the country's most significant Cyclospora outbreaks in years.
While the CDC's most recent nationwide surveillance report documented 145 domestically acquired cases across 17 states through mid-June, the outbreak has grown rapidly. Michigan has reported nearly 1,000 illnesses, prompting state officials to describe it as the largest Cyclospora outbreak in the state's history. Ohio has also confirmed hundreds of cases as investigators continue searching for a common source.
Although the CDC has not yet linked every state to a single contaminated product, the scale of illnesses has made this one of the largest Cyclospora outbreaks the United States has experienced in recent years.
While the Wyoming Department of Health is still investigating whether the state's lone non-travel-related case is connected to the broader outbreak, Peterson emphasized that residents shouldn't panic.
Wyoming health-care providers are equipped to diagnose and report cyclosporiasis, and the department will continue working with the CDC to determine whether Wyoming's cases become linked to the national investigation.
If a contaminated food product tied to Wyoming is identified, public health officials say they will notify residents and coordinate guidance with the Wyoming Department of Agriculture.
Until then, health officials recommend washing fresh produce, cooking foods when appropriate, choosing locally grown produce when available and contacting a health-care provider if diarrhea lasts for days, returns after improving or is accompanied by significant weight loss.
Kolby Fedore can be reached at kolby@cowboystatedaily.com.
