Updated July 10, 2026, 7:00 p.m. ET
- Infectious disease experts provide insights about cyclosporiasis as cases in Michigan are increasing by 20% to 30% daily.
- Since June 22, over 1,500 Michiganders have contracted the cyclospora parasite, leading to severe diarrhea.
- Doctors share information on testing, treatment, and prevention amid the outbreak.
The total number of individuals infected with cyclosporiasis, a parasite that leads to severe gastrointestinal distress, is escalating rapidly in Michigan, according to Dr. Anurag Malani, a health care epidemiologist at Trinity Health Ann Arbor Hospital. The increase stands at 20% to 30% each day.
Without a clear identification of the outbreak’s source, there seems to be no end in sight for this surge, Dr. Malani stated, who is also part of the Infectious Diseases Society of America.
To date, Michigan has reported 1,562 cases since the outbreak began in late June, but this number is likely an underestimate, he added.
“There are certainly more cases than what we’ve seen officially,” Malani mentioned. “Not everyone can get tested, and some might not even show symptoms.”
Given the incubation period of two days to two weeks after exposure and the lack of knowledge regarding the source, it’s probable that infections will continue to rise.
The most ill patients are going to emergency rooms, while others seek help from urgent care centers or their regular doctors.
“Typically, they experience prolonged diarrhea, and some might have additional gastrointestinal symptoms. Those who are hospitalized often complain of significant abdominal pain and nausea, along with dehydration,” he explained.
As of July 10, at least 44 individuals in Michigan have been hospitalized due to this current outbreak, according to state health officials.
What is cyclosporiasis?
Cyclosporiasis is caused by a parasite called cyclospora cayetanensis, as defined by the U.S. Food and Drug Administration.
This single-celled protozoan can infect humans through food or water contaminated by fecal matter, though it doesn’t typically spread from person to person due to its lifecycle, explained Dr. Rebecca Schein, a pediatric infectious disease specialist at the University of Michigan Health-Sparrow.
It can take time for the parasite to become infectious after passing out of an infected individual, which complicates tracing its source.
While cyclospora is not endemic to Michigan, it has historically been contracted by travelers visiting tropical regions or through imported produce from those areas.
In summer, Michigan sees several cases annually, usually about 50 per year, according to Schein.
Research indicates that the global incidence of cyclosporiasis is rising, possibly tied to climate change as suggested by Joseph Eisenberg, a professor of public health and epidemiologist at the University of Michigan’s School of Public Health.
How does Michigan’s outbreak compare to clusters in other states?
Currently, Michigan appears to have the highest number of cyclosporiasis cases in the nation, with 1,562 reported by July 10. However, the CDC data suggests only around half that number nationwide, with 843 cases across 31 states as of July 9.
The CDC remarked that several regions have noted an uptick in cases over the last two weeks compared to prior years, anticipating numbers to continue rising as more data is gathered.
As for nearby Ohio, reports indicate 364 statewide cases, yet local health departments claim numbers might be considerably higher in specific regions.
The Michigan Department of Health recently released a county breakdown showing the most affected counties:
- 1. Monroe: 215 cases
- 2. Wayne: 172 cases, including 12 in Detroit
- 3. Washtenaw: 159 cases
- 4. Lenawee: 155 cases
- 5. Oakland: 88 cases
- 6. Shiawassee: 82 cases
- 7. Jackson: 56 cases
- 8. Ingham: 55 cases
- 9. Livingston: 40 cases
- 10. Genesee: 35 cases
What caused previous cyclosporiasis outbreaks?
Health authorities are investigating this surge in Michigan and beyond without yet pinpointing a common cause. Previously, outbreaks in North America at various points have been linked to bagged salads, fresh herbs, and other produce items.
- In 1997, a significant outbreak occurred due to contaminated raspberries imported from Guatemala.
- In 2005, an outbreak was traced back to basil from South America.
- In 2018, a multistate outbreak emerged from lettuce served at McDonald’s.
- In 2019, imported basil from Mexico caused over 2,400 illnesses across multiple states.
How to protect yourself from cyclosporiasis
The Michigan Department of Health recently advised on cautious practices to reduce cyclosporiasis infection risk. Cooking leafy greens and herbs after washing them thoroughly can help eliminate the parasite.
For those who prefer consuming raw produce, the health authorities recommend:
- Wash hands before and after food preparation.
- Choose whole heads of lettuce over prewashed options and wash them carefully.
- Thoroughly wash herbs, separating leaves during rinsing.
- Trim and clean green onions thoroughly.
- Consider opting for frozen raspberries, as their texture makes them harder to clean.
- Rinse snow peas while rubbing their surface.
- Wash all produce under running water, even if peeling.
- Refrigerate cut or cooked fruits and vegetables quickly.
- Sanitize surfaces and utensils before and after use.
Will washing fruits and vegetables completely eliminate cyclospora?
No, washing alone won’t guarantee elimination. While good hygiene practices are beneficial, Dr. Eisenberg cautioned that cyclospora is particularly resilient.
“Washing won’t completely remove cyclospora, especially on textured fruits like raspberries,” he noted, adding that it may reduce contamination levels, which is still valuable.
The FDA highlights that common disinfectants do not kill cyclospora either, emphasizing the importance of cooking food.
Symptoms of cyclosporiasis infection
Symptoms typically manifest within 2 to 14 days after exposure and may include:
- Watery, potentially explosive diarrhea
- Abdominal cramps and bloating
- Loss of appetite
- Weight loss
- Fatigue
- Nausea
- Low-grade fever
- Less common vomiting
It’s critical for anyone with sudden gastrointestinal symptoms to consult a health care provider, as cyclosporiasis can be treated effectively with antibiotics if caught early.
Is it safer to eat locally grown produce?
With the uncertainty surrounding the outbreak’s source, Dr. Eisenberg notes that choosing locally sourced fresh produce can lower the risk of cyclospora infection.
“Michigan shows a higher rate of disease compared to other states,” he stated. “However, we are still unsure about the current outbreak’s cause.”
This means the risk may still lie within specific produce tied to certain suppliers, he added. The safest way to avoid infection remains to cook produce thoroughly and practice diligent washing.
Should everyone with cyclosporiasis be treated with antibiotics?
Even though many cases would resolve without treatment, there’s a recommendation for those with confirmed cyclosporiasis to receive antibiotics to alleviate symptoms faster.
“While some may experience only a self-limited infection, it’s often unpleasant and can last quite a while,” Dr. Schein concluded.
Individuals with weakened immune systems might need antibiotics to clear the infection more effectively, as they may not recover on their own.
Does it matter which type of antibiotic is used?
Yes, certain antibiotics like trimethoprim sulfamethoxazole, often branded as Bactrim or Septra, have proven most effective against cyclosporiasis.
If someone cannot take sulfa antibiotics, consulting a physician for alternatives is crucial.
Can my pet get cyclosporiasis?
No, Dr. Malani clarified. Only humans can host this parasite.
What should you do if you develop symptoms of cyclosporiasis?
If gastrointestinal symptoms arise, such as prolonged diarrhea and cramping, reaching out to a healthcare provider for testing is essential.
Dr. Adam Ressler from the University of Michigan emphasized the importance of confirming the diagnosis through stool testing prior to starting antibiotics, as using them without confirmation could worsen antibiotic resistance.
How long does it take to get a test result?
There are two test types available using stool samples. One is the Ova and Parasite (O&P) test, generally costing around $20 and taking three to five days for results.
The other is the BIOFIRE Gastrointestinal molecular test, which identifies multiple pathogens including cyclospora and returns results in about a day, although it’s costlier at around $475. Insurance verification is recommended for coverage.
(This story has been updated with new information.)
