Michigan Cyclosporiasis Outbreak Grows Amid National Surge

The Michigan Department of Health and Human Services (MDHHS) reported a “large and growing” cyclosporiasis outbreak with >300 confirmed cases in 21 counties by early July—about six times the state’s typical annual total of 50. CDC surveillance through mid-June listed 145 domestically acquired cases in 17 states; later updates suggest the national count exceeds 400 cases in 18 states.

Explosive Diarrhea Parasite Outbreak Expands Across U.S. as Cyclospora Cases Climb;Cyclospora Parasite Sickens 300 in Michigan: CDC Still Cannot Name Food SourceThe Guardian'Large and growing' parasitic infection outbreak spreading in Michigan, health officials sayMichigan Cyclospora Outbreak Hits 300 Cases in 21 CountiesABC7Chicago.com

Cyclosporiasis peaks May-August, matching fresh-produce consumption. Past U.S. clusters involved raspberries, basil, cilantro, snow peas, mesclun lettuce, and bagged salads; no single source is identified for this surge.

Michigan Cyclospora Outbreak Hits 300 Cases in 21 Counties

• Michigan: >300 cases across Monroe, Lenawee, Washtenaw, Wayne, Livingston, Shiawassee, Jackson, and other counties; 27 cases in Wayne County alone. National (CDC, mid-June): 145 cases in 17 states, 20 hospitalizations, no deaths.

Cyclospora Parasite Sickens 300 in Michigan: CDC Still Cannot Name Food Source

MDHHS, the CDC, the FDA, and state partners are interviewing patients, testing stool, and tracing supply chains. Officials advise thorough washing of all fresh produce, refrigeration of pre-cut items, and prompt care for persistent watery diarrhea. The CDC recommends a ten-day regimen of trimethoprim-sulfamethoxazole (TMP-SMX) for confirmed infections.

'Large and growing' parasitic infection outbreak spreading in Michigan, health officials say

Routine stool cultures miss Cyclospora; diagnosis needs an ova-and-parasite exam, acid-fast stain, or PCR. Lack of molecular typing tools hampers linking cases to a common food, and many clinicians do not order these tests, causing under-diagnosis.

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Most healthy adults recover; immunocompromised patients—organ-transplant recipients, cancer patients, elderly—risk severe, prolonged illness and dehydration, and most hospitalizations involve these groups.

Cyclospora Parasite Sickens 300 in Michigan: CDC Still Cannot Name Food Source

• “We are working closely with our state and local partners to identify the source of this outbreak that is making so many people ill as quickly as possible,” — Lynn Sutfin, MDHHS public information officer

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• “But now we're starting to have more domestic cases as well,” — Peter Chin-Hong, MD, UCSF infectious diseases specialist

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• “If you're in an area that's been affected and you have sudden ongoing watery diarrhea, you should definitely seek a physician and get treatment,” — Zoe Weiss, director of clinical microbiology, Tufts Medical Center

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• “Based on the unusual number of cases we have identified in a little over a week, we anticipate additional cases of illness being reported,” — Natasha Bagdasarian, MDHHS chief medical executive

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The CDC’s national tally omits Michigan’s >300 cases, creating a gap between federal (145) and state (>300) data. Media reports vary, citing >400 cases in 18 states or the 145-case figure. No specific food has been confirmed, and the true burden is likely higher due to missed diagnoses.

Cyclospora Parasite Sickens 300 in Michigan: CDC Still Cannot Name Food Source

Investigators will keep interviewing patients, expand testing, and trace fresh-produce supply chains through August, the end of the cyclosporiasis season. The CDC will update counts weekly; the FDA stands ready to issue recalls if a source is found.

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