Cyclosporiasis, a serious parasitic infection that causes “explosive” watery diarrhea, is affecting dozens of people in Michigan and other parts of the United States.
Cases of this gastrointestinal illness, caused by a parasite that is transmitted through contaminated food, have been increasing since May, according to the Centers for Disease Control and Prevention (CDC). At least 20 people have been hospitalized across the country.
CDC is working to identify possible sources of the parasitic infection, which is often linked to fresh produce.
Last week, an unusual outbreak of cases was reported in the Midwest. Michigan health officials are investigating a “sudden and significant” increase in cyclosporiasis cases, the Michigan Department of Health and Human Services (MDHHS) told the show. .
Since June 22, 2026, more than 170 cases of cyclosporiasis have been reported in southeastern Michigan, up from 150 a few days earlier. According to authorities, the numbers are not normal for the state. “In Michigan, typically 50 cases are identified per year,” an MDHHS spokesperson said.
Cyclosporiasis is a seasonal disease in the United States, and cases typically peak between May and August, according to the CDC.
It is not uncommon for infections to increase in the summer. However, the latest surge in Michigan has health officials on high alert and they are urging people to seek medical care if they develop symptoms.
The national panorama
Nationally, at least 145 cases of cyclosporiasis were reported in 17 states across the country between May 1 and June 16, according to the most recent data from the CDC. These do not include the recent increase in cases in Michigan.
New York has reported the highest number of cases, followed by Illinois and Texasaccording to the CDC. Infected people are between 5 and 86 years old. At least 20 hospitalizations have been recorded, but no deaths have been reported so far.
“The actual number of people sick with cyclosporiasis is likely to be higher than the number reported,” the CDC explained.
Since last week, more than 170 cases of cyclosporiasis have been reported in seven Michigan counties: Monroe, Lenawee, Washtenaw, Wayne, Livingston, Shiawassee and Jackson. The MDHHS noted that, at this time, the source of the outbreak has not been identified.
CDC is working with the Food and Drug Administration (FDA) and local authorities to investigate cases in several states. The agency said people became ill after eating food in the United States, and none reported traveling abroad in the previous weeks.
Currently, “there is no evidence of a single outbreak of cyclosporiasis that spans multiple states and links all cases,” the CDC said in a July 1 update. The investigations continue.
Several hundred cases of cyclosporiasis are typically reported in the United States each year. In recent years, the number of infections reported in the country has increased significantly.
In 2019, an unusually high number of cyclosporiasis infections were identified (4,703), according to a 2023 CDC report.
What is cyclosporiasis?
Cyclosporiasis is a type of food poisoning. It can cause severe diarrhea, but is usually not life-threatening, the CDC added.
The cause, the microorganism Cyclospora cayetanensis, is a parasite found in human feces.
Cyclosporiasis is present in many countries, but the infection is more common in tropical and subtropical regions.
How is it transmitted?
Cyclosporiasis is transmitted through the fecal-oral route. People become infected by ingesting the tiny Cyclospora parasite by consuming food or water contaminated with feces.
Infected people shed the parasite in their feces. The CDC explains that it usually takes between one and two weeks outside the body for the parasite to become infectious, so person-to-person transmission is very unlikely.
In the United States, outbreaks of cyclosporiasis have been linked to fresh fruits and vegetables, such as basil, cilantro, raspberries and peas, the CDC added.
In 2022, a large cluster of cases in Florida was traced to a Caesar salad kit containing romaine lettuce.
The best way to prevent infection is to avoid consuming food or water that may be contaminated with feces, the CDC added. Following proper hand hygiene and safe food handling practices can also reduce the risk of contracting foodborne illness.
The symptoms
Symptoms of the disease appear between two and 14 days after ingesting the Cyclospora parasite.
The main symptom of cyclosporiasis is intense, watery, “explosive” diarrhea.
Infected people may also experience loss of appetite, stomach cramps, nausea, vomiting and a low-grade fever, according to the Cleveland Clinic.
Cyclosporiasis can last from a few days to more than a month or even longer. Symptoms may come in waves and come back more than once after they go away, known as “relapses,” the CDC added.
The infection is usually treated with a combination of antibiotics. However, most people with a healthy immune system will recover from cyclosporiasis on their own, according to the CDC.
People with a weak immune system are at higher risk of prolonged illness and relapses of symptoms.
People who develop symptoms of cyclosporiasis or sudden, severe gastrointestinal illness should contact their healthcare provider, the CDC added. If you test positive for the parasite, contact your local health department.
