For two weeks, the diarrhea does not stop. Twenty episodes a day, sometimes more. The patient loses weight, cannot hold fluids, and presents to a clinic where the standard stool panel comes back clean. Unless the ordering physician thinks specifically to request an assay for Cyclospora cayetanensis — a microscopic, food-borne parasite that standard ova-and-parasite tests routinely miss — she may be sent home undiagnosed, untreated, and contagious. This is the baseline problem with Cyclospora. It was already one of the most under-detected pathogens in the American food system. Then the federal government made the situation structurally worse.

In 2024, the CDC maintained active surveillance for cyclosporiasis through its established enteric disease tracking infrastructure — a system that cross-references state health department case reports, laboratory data, and epidemiological signals to identify clusters and trace contamination back to a food source. Last year, that surveillance was downgraded from active to passive. The distinction matters enormously. Active surveillance means the agency is proactively reaching out to states, standardizing reporting, and running the epidemiological connective tissue between scattered cases. Passive surveillance means the agency waits for states to file reports on their own schedule, in their own formats, with no federal coordinator pulling the threads together.

The result is exactly what epidemiologists warned it would be: a parasite with a notoriously long incubation period of one to two weeks, capable of spreading through fresh produce across a continent-wide supply chain, is now being tracked by a system that cannot move fast enough to identify the contaminated source before millions more servings reach consumers. By the time a cluster is recognized under passive surveillance, the implicated food has already been eaten.

As of this reporting, cyclosporiasis cases have been confirmed across 34 states, with the outbreak appearing to still be in an active phase. Arizona has reported at least 19 confirmed cases; Georgia's numbers have climbed steadily in recent weeks. These are confirmed figures — the actual case count, accounting for the routine under-diagnosis the CDC itself has historically acknowledged for this pathogen, is likely a significant multiple of the official tally. Cyclospora does not show up on the rapid panels used in most urgent care settings. It requires a specific PCR assay or a modified acid-fast staining technique that most community labs do not run unless a physician explicitly requests it. Many do not know to.

The downgrade of active surveillance did not happen in a vacuum. It arrived alongside a broader restructuring of CDC programs and a series of budget and staffing reductions that have been well-documented in public budget requests and agency reorganization announcements. The specific unit responsible for Cyclospora tracking — part of the Division of Foodborne, Waterborne, and Environmental Diseases — lost personnel and had its operational scope narrowed. Officials within the current administration have disputed the causal link, arguing that state-level reporting capacity is sufficient and that the federal role was redundant. That argument is difficult to square with the current map, which shows cases scattered across three dozen states with no publicly confirmed common source.

Cyclospora cayetanensis has a specific epidemiological fingerprint that makes it both dangerous and traceable — when the tracing infrastructure exists. It does not survive cooking. It is almost exclusively transmitted through fresh produce: cilantro, raspberries, basil, snap peas, and leafy greens have all been implicated in past U.S. outbreaks. Many of those produce items are imported. The parasite's oocysts require days to weeks outside a host to become infectious, meaning contamination typically happens pre-harvest, at the farm or in irrigation water. Identifying the source requires rapid, coordinated case interviewing — asking sick patients what they ate and when, before the memory fades and the produce lot number disappears from store records. That work requires active surveillance. Passive surveillance, by design, is too slow.

Physicians treating patients in states where cases have been confirmed are working without the kind of real-time federal signal that would prompt them to add Cyclospora-specific testing to their differential. This is not a theoretical gap. Gastroenterologists and infectious disease specialists have noted in professional forums that the absence of a visible federal alert has meant some clinicians are not thinking of Cyclospora when they see prolonged watery diarrhea in patients who have not recently traveled internationally — the traditional risk profile that triggers the question. Domestic outbreaks tied to domestic or imported produce have repeatedly demonstrated that Cyclospora is not only a traveler's disease, but the clinical index of suspicion has not caught up to that reality, and federal guidance is the mechanism by which it does.

The treatment, when a diagnosis is finally made, is straightforward: trimethoprim-sulfamethoxazole, typically for seven to ten days. Patients improve. The problem is the weeks of illness, the weight loss, the missed work, and in vulnerable populations — immunocompromised individuals, the elderly, young children — the genuine risk of serious dehydration and complications that accumulate before anyone identifies what is wrong. A functioning active surveillance system does not eliminate Cyclospora. It shortens the time between contamination and recall, between outbreak and diagnosis, between a sick patient and an answer. That is precisely what has been removed. The bill for that decision is now being paid in emergency room visits across 34 states.