California Combats Largest Mushroom Poisoning Outbreak in the Country

State health officials on Wednesday issued their second warning this season to avoid mushroom foraging as illness and deaths from eating wild mushrooms known as death caps rise to unprecedented highs.

Thirty-five people have gotten sick so far this season, three needed liver transplants, and three died, compared to a typical year that sees only three to five cases. Doctors worry more cases are coming amid a “super bloom” of death caps, sparked by early rains and warm temperatures in the fall.

“We anticipate that these mushrooms could continue to be fruiting in abundance throughout the rainy season in California,” said Dr. Craig Smollin, medical director of the San Francisco division of the California Poison Control System.

Immigrants from Mexico and China make up a disproportionate number of the cases, as death caps, or Amanita phalloides, look very similar to edible mushrooms that grow in those countries. The California Department of Public Health released a series of fact sheets and videos on Wednesday in multiple languages, including Mixteco, an indigenous language of Mexico spoken by communities in Monterey County, where the first poisonings emerged in November.

Since then, people have been treated in hospitals throughout the Bay Area after eating mushrooms found in the Oakland Hills, Stinson Beach and Pinnacles National Park, among other sites, though Smollin said that they grow along the West Coast and that no part of California is a death cap-free zone. Some dogs have also died.

“It’s a really dangerous time to be mushroom hunting and foraging right now,” said Dr. Rita Nguyen, assistant state public health director. “It can be very hard, even for experts, to identify the difference between edible mushrooms and not.”

Symptoms of death cap poisoning include nausea, vomiting and diarrhea, and can occur 6 to 24 hours after ingestion. Extreme cases can lead to liver failure, necessitating an urgent liver transplant or death. Cooking, boiling or freezing the mushrooms does not inactivate the toxin.

“A single bite of the mushroom could cause significant toxicity,” Smollin said.

Local mushroom experts and enthusiasts have bemoaned the state’s messaging around the poisonings as narrow and fear-based. Many would prefer to see an emphasis on education, rather than a prohibition on all foraging, and point out that touching, smelling and looking at mushrooms is safe.

“There’s a lot more nuance,” said Debbie Viess, co-founder of the Bay Area Mycological Society. “It’s much more important to steer people to places where they can educate themselves about the safety and the dangers of eating wild mushrooms.”

Viess said field reports coming into her organization suggest the growth of death caps may be slowing in the Bay Area, while another kind of poisonous mushroom known as the destroying angel, or Amanita ocreata, is starting to pop up.

People who believe they or a family member may have ingested a toxic mushroom — or health care providers who have a patient showing signs of mushroom toxicity — can call the state’s toll-free poison control hotline 24/7, free of charge for advice: 1-800-222-1222.

Translation services are available in any language, and all personal information is kept confidential, said Dr. Cyrus Rangan, a pediatrician and toxicologist with poison control.

“We can then determine whether you need to go into the emergency department or whether we, as poison experts, can help you treat the situation at home,” he said.