By Margaret Farley Steele
THURSDAY, June 1, 2017 (HealthDay News) -- A bumper crop of deadly wild "death cap" mushrooms in northern California is likely to blame for the poisonings of 14 people in December, health officials say.
The culprit: Amanita phalloides, believed to be the world's most dangerous mushroom.
All 14 recovered, but three required liver transplants, and a toddler suffered permanent brain damage, the researchers reported.
The U.S. Centers for Disease Control and Prevention recommends that anyone picking wild mushrooms have them evaluated by a specialist before eating them.
"Wild-picked mushrooms should be evaluated by a trained mycologist [fungi expert] before ingestion," according to the report published in the June 2 issue of the CDC's Morbidity and Mortality Weekly Report.
"Inexperienced foragers should be strongly discouraged from eating any wild mushrooms," wrote Dr. Kathy Vo, of the University of California, San Francisco's department of emergency medicine, and colleagues.
The 14 people described in the report had eaten wild mushrooms they picked themselves or received from others.
In previous years, the California Poison Control System had only received a few reports of mushroom poisonings each year.
The large outbreak may be related to a reported increase in the growth of wild mushrooms in 2016, triggered by greater rainfall and warm weather at the end of northern California's autumn.
"Although weather conditions and increased numbers of A. phalloides poisonings do not prove a cause-and-effect relationship, early seasonal rainfall and warmer subsequent temperatures made a substantial contribution to mushroom proliferation," the authors of the report noted.
In addition, an increase in amateur foraging and wild-crafting (gathering plant material for food or medicinal purposes) has raised the risk for poisoning, Vo's team said.
After eating just one that he picked in Santa Rosa, a 37-year-old was hospitalized for six days, according to the report.
An 18-month-old became critically ill after nibbling one-half of a mushroom cap given to her mother by a stranger who had picked mushrooms in the mountains that morning.
The child's mother, father, and two adults who had joined them for dinner also became ill.
The child developed irreversible liver failure that affected her brain. She required a liver transplant and suffered "permanent neurologic impairment," the report said. Another adult who attended that dinner also needed a liver transplant.
Health-care providers should contact their local poison control center for assistance if they see patients who are ill after eating foraged mushrooms, the study authors advised.
A treatment already used in Europe -- intravenous silibinin -- is being tested in clinical trials in the United States, the report noted.