The Metro: What’s making hundreds of Michiganders sick? Health officials are still looking

A parasite that causes “explosive diarrhea” has sickened 700 Michiganders, and health officials still haven’t found the source. Oakland County Health Officer Kate Guzman explains the hunt.

KateGuzman

Kate Guzman, the Oakland County health officer, joins The Metro in WDET's Detroit studio on July 6, 2026. Guzman, a nurse by training, spoke with host Robyn Vincent about the cyclospora outbreak that has sickened more than 700 people across Michigan.

A parasite called cyclospora is spreading through Michigan, and health officials still haven’t found the source.

In a normal year, the state sees about 50 cases; in the last two weeks, it has counted 700 infections among people aged 8 to 84, according to Dr. Natasha Bagdasarian, chief medical officer for the state of Michigan.

It usually rides in on fresh produce — berries, herbs, leafy greens — but so far, no food has been named. Oakland County health officer Kate Guzman, a nurse by training, joins host Robyn Vincent to explain how investigators hunt for an invisible source, one interview at a time — and what it means that, a year ago, the Centers for Disease Control and Prevention stopped requiring states to report this exact parasite to one of its main early warning systems.

Editor’s note: This conversation was recorded before the latest case counts were released. The story has been updated to reflect the Michigan Department of Health and Human Services’ latest infection count. The outbreak is ongoing and the number continues to rise.

Hear the full conversation using the media player above.

Listen to The Metro weekdays from 10 a.m. to noon ET on 101.9 FM and streaming on-demand. Never miss an episode — subscribe to The Metro on Apple Podcasts, Spotify, YouTube, or NPR, or wherever you get your podcasts.

Trusted, accurate, up-to-date.

WDET strives to make our journalism accessible to everyone. As a public media institution, we maintain our journalistic integrity through independent support from readers like you. If you value WDET as your source of news, music and conversation, please make a gift today.

Donate today »

More stories from The Metro

Authors

  • Robyn Vincent
    Robyn Vincent is the co-host of The Metro on WDET. She is an award-winning journalist, a lifelong listener of WDET, and a graduate of Wayne State University, where she studied journalism. Before returning home to Detroit, she was a reporter, producer, editor, and executive producer for NPR stations in the Mountain West, including her favorite Western station, KUNC. She received a national fellowship from Investigative Reporters and Editors for her investigative work that probed the unchecked power of sheriffs in Colorado. She was also the editor-in-chief of an alternative weekly newspaper in Wyoming, leading the paper to win its first national award for a series she directed tracing one reporter’s experience living and working with Syrian refugees.
  • The Metro