A parasite most Americans have never heard of has produced the largest outbreak of its kind in United States history, and it is still going. The CDC has confirmed 15,716 cases of cyclosporiasis across 47 states since May 1, with 828 hospitalizations and two deaths.
For scale, the same period last year produced 1,180 cases. This is more than thirteen times that.
The Numbers
As of the CDC’s August 18 update, using data through August 17: 15,716 laboratory confirmed domestically acquired cases across 47 states plus Washington D.C. and Puerto Rico. Only Delaware, New Mexico and Hawaii have been spared.
There are 828 hospitalizations. Two people have died, both Michigan residents with underlying conditions. Illness onset dates run from May 1 through August 13, with a median onset of July 7. Patients range in age from 1 to 99, median 46, and 57 percent are female.
Another 11,841 cases are still under investigation and not yet in the confirmed count.
Michigan Is Carrying Almost All of It
This is not evenly distributed. Michigan alone accounts for 13,909 cases, 314 hospitalizations and both deaths. That is roughly 88 percent of the national total in a single state.
That concentration is the clearest fingerprint of a distribution problem rather than a widespread contamination event. One supply chain, feeding one region hardest.
It Came From Lettuce
Investigators traced it to processed iceberg lettuce from central Mexico. Taylor Farms de Mexico, part of Taylor Fresh Foods, issued a recall on July 17 covering product with best by dates from July 18 through August 3.
That included Marketside brand lettuce sold at Walmart, with confirmed distribution to 31 states and possible distribution to nine more. The contaminated supply also reached Jack in the Box locations, and reporting has tied it to Taco Bell as well.
The FDA ran an onsite inspection and sampling at the Mexican facility alongside Mexican officials and now says it is confident all recalled lettuce tied to this outbreak is off the market. The investigation remains open.
What Cyclospora Actually Does
Cyclospora cayetanensis is a single celled parasite, not a bacterium. Incubation runs about one to two weeks, which is long enough that most people never connect the illness to the meal.
Symptoms are watery diarrhea, loss of appetite, weight loss, cramping, nausea and fatigue. Untreated it can persist for weeks and relapse. The treatment is trimethoprim sulfamethoxazole for seven to ten days, which means you need an actual diagnosis rather than waiting it out.
The Detail Your Doctor May Not Know
This is the most useful thing in the entire CDC advisory. Routine ova and parasite testing does not reliably detect Cyclospora. Clinicians have to specifically order testing for it.
That means the true case count is higher than 15,716, possibly much higher, because anyone whose doctor ran a standard panel and found nothing was told they had a stomach bug. If you have had persistent watery diarrhea since June and got a clean test, it is worth asking about this by name.
Washing Helps. Disinfecting Does Not.
Chemical disinfection does not reliably kill Cyclospora. Bleach solutions, produce washes and vinegar soaks are not a defense against this particular parasite.
What helps is running water and friction. Wash produce thoroughly under running water. Cooking kills it, but the foods this parasite rides on are almost always eaten raw, which is the recurring problem with produce borne illness. Our coverage of the ongoing jalapeno Salmonella outbreak runs into the same structural issue.
Two Different Case Counts Are Circulating
You will see conflicting numbers this week and both are correct. The CDC’s national surveillance figure is 15,716 cases across 47 states with 828 hospitalizations, counting all domestically acquired cases this season.
The FDA’s outbreak specific count, as of August 13, is 9,481 illnesses with 398 hospitalizations across 17 states, because the FDA counts only cases epidemiologically linked to the Taylor Farms lettuce. Any story quoting one number without saying which is which is going to confuse people.
Why This Got So Little Attention
An outbreak thirteen times larger than last year’s, in 47 states, with two deaths, has generated a fraction of the coverage that a much smaller Salmonella recall would.
Part of that is the name. Salmonella and Listeria are household words and Cyclospora is not. Part of it is the incubation period, which decouples the illness from the meal and makes it feel less like an event. And part of it is that the recall happened a month ago, which the news cycle treats as resolved even when the case count is still climbing.
The other reason is that produce outbreaks have become background noise. Leafy greens have been implicated in so many events over the past decade that a lettuce recall reads as routine, and routine does not travel. That is exactly the environment in which a record breaking outbreak can run for four months without most people knowing it exists.
There is also a diagnostic lag baked into the numbers. Because confirmation requires a specific test that most labs do not run by default, and because the parasite takes one to two weeks to make anyone sick, the case count the CDC publishes on any given Tuesday describes infections that happened weeks earlier. The curve you are looking at is history, not the present.
Frequently Asked Questions
How many people are sick?
15,716 confirmed cases across 47 states, D.C. and Puerto Rico, with 828 hospitalizations and two deaths, per CDC data through August 17.
What caused it?
Processed iceberg lettuce from central Mexico, recalled by Taylor Farms de Mexico on July 17.
Is the recalled lettuce still in stores?
The FDA says it is confident all recalled product tied to this outbreak is off the market. The investigation is still open.
What are the symptoms?
Watery diarrhea, cramping, nausea, loss of appetite, weight loss and fatigue, beginning about one to two weeks after exposure.
How is it treated?
With trimethoprim sulfamethoxazole for seven to ten days. It requires a diagnosis, and doctors have to order Cyclospora testing specifically.
Does washing produce protect you?
Washing under running water helps. Chemical disinfectants and produce washes do not reliably kill this parasite.
