What Happened to Multistate Cyclosporiasis Outbreak (2026)?

A multistate outbreak of cyclosporiasis, an intestinal illness caused by the Cyclospora cayetanensis parasite, is ongoing in the United States in 2026. As of mid-June 2026, the Centers for Disease Control and Prevention (CDC) reported 145 domestically acquired cases across 17 states. Additionally, Michigan health officials reported a significant surge of over 170 cases across at least seven counties by early July 2026, bringing the total reported cases nationwide to over 300. The illness is characterized by severe, sometimes "explosive," watery diarrhea, abdominal cramps, nausea, and fatigue, and can last for weeks if untreated.

Cyclosporiasis is typically acquired through the consumption of food or water contaminated with Cyclospora cayetanensis feces. Past outbreaks have frequently been linked to fresh, imported produce such as raspberries, basil, cilantro, snow peas, and mesclun lettuce. The parasite is resistant to routine disinfection methods like rinsing with water, making it difficult to remove from produce. While the specific source for the 2026 outbreak is still under investigation, the pattern of previous outbreaks strongly suggests contaminated fresh produce as a likely vehicle. In 2023, CDC scientists also discovered that Cyclospora has at least three distinct genetic populations, a finding that could potentially aid public health officials in tracing outbreak sources more effectively in the future.

Key turning points in the 2026 outbreak began with the official start of the cyclosporiasis season on May 1, 2026, a period when case counts typically rise. Illness onset dates for the initial 145 domestically acquired cases reported by the CDC ranged from May 1 to June 6, 2026. By June 16, 2026, the CDC had officially reported these 145 cases across 17 states. A significant development occurred in late June and early July 2026, when Michigan health officials reported an unusually large surge of over 170 cases across several counties, prompting state-level health alerts and adding considerably to the national tally.

The consequences of this outbreak include at least 20 hospitalizations nationwide as of mid-June 2026, though no deaths have been reported. The ongoing investigation necessitates extensive collaboration between local, state, and federal health agencies, including the CDC and the U.S. Food and Drug Administration (FDA), to identify the precise source of contamination and implement measures to prevent further spread. Public health advisories have been issued, emphasizing the importance of safe food handling practices, such as thorough washing of fruits and vegetables.

As of July 2, 2026, the multistate cyclosporiasis outbreak remains actively ongoing. The CDC is monitoring 145 cases across 17 states, with Michigan reporting an additional 170 cases, bringing the total to over 300. The specific source of contamination for the current outbreak is still under investigation, and public health agencies are continuing their efforts to pinpoint the responsible food items. Given that the cyclosporiasis season typically extends until August 31, health officials anticipate that new cases may continue to emerge.