Last Updated on 2 hours ago by TodayWhy Editorial
The CDC parasite outbreak making headlines this summer has a name: cyclosporiasis. It’s a gut infection caused by a tiny parasite called Cyclospora. As of mid-June, CDC surveillance data counted 145 cases across 17 states. Michigan alone has since reported over 300 more. So why are cases climbing right now, and why is it so hard to find the cause?
Why Is the CDC Parasite Outbreak Growing?
Three things are happening at once.
1. It’s the parasite’s natural season. Cyclospora cases rise every year between May and August in the US. This year’s rise started right on schedule, on May 1.
2. Most doctors don’t test for it. Cyclospora is not part of a standard stool test. A doctor has to order the test by name. That means many sick people are never diagnosed. Their illness just looks like a long stomach bug. Health officials say the real number of cases is almost certainly much higher than 145.
3. A separate spike in Michigan is adding to the alarm. Michigan usually sees about 50 cyclosporiasis cases a year. In just over a week at the end of June, it recorded more than 170 cases. By July 2, that number had passed 300. Health officials don’t yet know if these cases share the same source as the national count. It could be a second, separate cluster.
Why Can’t the CDC Find the Source?
Past Cyclospora outbreaks in the US have usually been traced back to fresh produce. Common culprits include cilantro, basil, raspberries, snow peas, and bagged salad kits. A 2022 outbreak in Florida was linked to a Caesar salad kit.
But as of early July 2026, investigators have not confirmed a source for this year’s cases. The parasite spreads through food or water contaminated with feces. Symptoms can take one to two weeks to show up after eating something contaminated. That long delay makes it hard to trace an illness back to a single meal.
What Are the Symptoms?
- Watery, “explosive” diarrhea
- Loss of appetite
- Stomach cramps and bloating
- Nausea or vomiting
- A mild fever, in some cases
Symptoms can last from a few days to more than a month. They can also fade and then come back if the infection isn’t treated. The illness does not spread from person to person — you have to eat or drink something contaminated to catch it.
What Should You Do?
If you have watery diarrhea for more than a few days, see a doctor. Ask specifically about Cyclospora testing. The infection is treated with a short course of antibiotics. Most healthy people recover on their own. People with weaker immune systems can get sicker and take longer to heal. To lower your risk, wash fresh fruit and vegetables well under running water, and scrub firm produce before eating it.
This isn’t the only illness spreading in the US this year that’s easy to miss at first. Hantavirus is another example. Its early symptoms are often mistaken for the flu.
Frequently Asked Questions
How many cases are in the CDC parasite outbreak?
The CDC had confirmed 145 domestically acquired cases across 17 states as of June 16, 2026. That count does not include Michigan’s separate cluster of over 300 cases reported since late June.
Is cyclosporiasis contagious?
No. It does not spread from person to person. You get it by eating or drinking something contaminated with the parasite.
How long do symptoms last?
Symptoms usually appear one to two weeks after eating contaminated food. Untreated, the illness can last from a few days to more than a month, and symptoms can come back after they seem to fade.
What food is causing the outbreak?
As of early July 2026, no specific food has been confirmed as the source. Past outbreaks have been linked to fresh herbs and produce like cilantro, basil, and bagged salad kits.
Sources: CDC cyclosporiasis surveillance data (cdc.gov), updated June 2026; Michigan Department of Health and Human Services; reporting from ABC News, NBC News and TODAY, July 1-3, 2026.