AUTHORITIES IN SONOMA COUNTY are investigating the cause of illnesses associated with last weekend’s Tough Mudder event, which took place at Sonoma Raceway and involved a muddy obstacle course. 

Sonoma County officials said they are operating under the assumption that the illnesses are being caused by a waterborne bacterial pathogen known as Aeromonas until the investigation can be fully completed. 

A spokesperson for the Tough Mudder event said Thursday that the organization followed all necessary protocols before and after the event. 

Reports of rashes, fever, vomiting and other ailments prompted Sonoma County officials to issue a health advisory Wednesday. 

 “We are requesting that clinicians obtain cultures from infected patients and report the results to us,” Matt Brown, a spokesperson for the county, said Thursday. “We have received seven confirmed cases of Aeromonas thus far.” 

The Tough Mudder race involved extensive skin exposure to mud, according to the county, adding that the most affected people have pustular rash, fever, myalgias and headache.  

Charlie Bernard, a spokesperson for Tough Mudder, said the health and safety of participants is “always our top priority.” 

“All necessary protocols were followed in preparation for, and during, the event,” said Bernard in an email Thursday. “Our thoughts are with those affected and we are actively investigating to understand exactly what occurred.” 

Bernard said Tough Mudder has reached out to every registered participant and spectator, urging them to contact their medical professional or emergency room if they are experiencing an unresolved or worsening rash, flu-like symptoms, fever, fatigue or myalgia, commonly known as nerve pain.  

The county has provided this Canadian link for people who want to learn more about Aeromonas: 

Katy St. Clair got her start in journalism by working in the classifieds department at the East Bay Express during the height of alt weeklies, then sweet talked her way into becoming staff writer, submissions editor, and music editor. She has been a columnist in the East Bay Express, SF Weekly, and the San Francisco Examiner. Starting in 2015, she begrudgingly scaled the inverted pyramid at dailies such as the Vallejo Times-Herald, The Vacaville Reporter, and the Daily Republic. She has her own independent news site and blog that covers the delightfully dysfunctional town of Vallejo, California, where she also collaborates with the investigative team at Open Vallejo. A passionate advocate for people with developmental disabilities, she serves on both the Board of the Arc of Solano and the Arc of California. She lives in Vallejo.