What You Need to Know About the Parasite Outbreak Spreading in Michigan and Ohio

A parasite called cyclospora is making thousands of people sick in Michigan and Ohio. State health officials report more than 2,800 confirmed cases, with Michigan accounting for the vast majority at 2,640 cases and Ohio reporting 177. The Centers for Disease Control and Prevention, the federal health agency, has counted only 843 confirmed cases so far across 31 states—far fewer than state numbers show. This gap exists because federal reporting moves slower than state reporting, not because anyone is disagreeing about the facts.

Eighty-six people have been hospitalized. No deaths have been reported so far.

Why Do the Numbers Differ?

When someone gets sick and gets tested, the result doesn't instantly reach federal databases. It takes time. A cyclospora infection usually causes symptoms about two weeks after exposure. The CDC assumes it takes another six weeks from symptom onset until a case is officially logged in the national system—time for people to seek care, get results back, and have those results reported upward through the system. States, meanwhile, count cases much faster as doctors report them locally. Think of it like tracking packages: FedEx's local hub counts them immediately, but corporate headquarters takes longer to verify and log everything. Both numbers are accurate for what they're measuring. It just means the federal count will keep climbing for weeks even after the outbreak peaks.

Michigan's outbreak began accelerating in late June. The state health department first announced it on July 1, when it had found more than 170 cases. By July 6, that number jumped to around 700. By July 9, it had more than doubled again to 1,251. By July 13, the total had reached 2,640. Forty-four people in Michigan had been hospitalized as of July 9. The outbreak is concentrated in seven counties in the southeast part of the state: Monroe, Lenawee, Washtenaw, Wayne, Livingston, Shiawassee and Jackson.

Ohio's outbreak is smaller. The state health department reported 177 cases as of July 2, most of them occurring in June after June 20.

Where Is It Coming From?

Neither Michigan nor Ohio has found the source of the outbreak yet. Health officials have not identified a specific farm, food supplier, or restaurant. However, based on what causes cyclospora outbreaks historically, Michigan has warned restaurants and food businesses to be especially careful with leafy greens, snow peas, certain herbs, and raspberries. These foods have been linked to cyclospora outbreaks in the past.

Dr. Natasha Bagdasarian, Michigan's chief medical officer, said "there is clearly a linked outbreak happening right now." That means the cases are connected to the same source, not random individual infections.

Why Can't Health Officials Find the Source Faster?

Public health departments are stretched thin. In March 2025, the federal government cut $11.4 billion in funding to state and local health departments. Michigan's public health labs lost $5.5 million of that. With fewer staff, it takes longer to interview sick people and trace what they ate. Interviews are happening six to eight weeks after people got sick instead of sooner. The longer you wait, the less people remember about the food they ate, making it harder to track down the source.

Cyclosporiasis causes severe watery diarrhea, fatigue, and stomach cramping. Most people get better on their own without needing to go to the hospital. The outbreak is still growing, and investigators are working to find its source.