Tourists may be behind 'unprecedented' surge in Calif. mushroom poisonings

"Over the weekend, three adults were hospitalized after eating wild mushrooms they collected in the rural area of Deer Park, the county's Health and Human Services Agency said in a Tuesday news release. The three people were not Napa County residents and were foraging mushrooms specifically between Deer Park Road, Fawn Road and Silverado Trail."

"The agency said the poisonings are part of an "unprecedented outbreak" of mushroom-related illnesses and deaths across California. According to the California Department of Public Health, there have been 47 cases, including four deaths, since Nov. 18, 2025. Of these cases, hospitalizations occurred in six Bay Area counties: Alameda, Contra Costa, San Francisco, San Mateo, Santa Clara and Sonoma."

""These cases are a continuation of a mushroom poisoning outbreak that began in November and is continuing for longer than usual. It is also unusually large and widespread," he said. "These cases are a continuation of a mushroom poisoning outbreak that began in November and is continuing for longer than usual. It is also unusually large and widespread," he said."

"Health officials said recent rains have boosted wild mushroom growth and could be one of the main factors driving the outbreak, including the most recent poisoning in Napa. "It's possible that allowed for another crop of these mushrooms to come up. It's not unheard of that these mushrooms can grow year-round, not just during the rainy season," Smollin said."

Bay Area health officials are warning the public about an unusual increase in mushroom poisonings across the region and the state, including recent cases in Napa County. Three adults were hospitalized after eating wild mushrooms they collected in the Deer Park area, specifically between Deer Park Road, Fawn Road, and Silverado Trail. The poisonings are described as part of an unprecedented outbreak of mushroom-related illnesses and deaths across California. The California Department of Public Health reported 47 cases and four deaths since Nov. 18, 2025, with hospitalizations in multiple Bay Area counties. Health officials began tracking the outbreak after noticing the increase in November, noting that California typically sees about five cases per year. Recent rains may have boosted wild mushroom growth and enabled another crop to appear, potentially contributing to the outbreak.

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