"Death cap" mushrooms picked in the greater San Francisco Bay Area last year poisoned 14 people, including an 18-month-old girl, according to a piece published in the June 2 issue of the Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report.
Although all but one recovered completely, three had to have liver transplants. In addition, the toddler suffered "permanent neurological damage" from eating what's considered the world's most dangerous mushroom.
"Death cap" mushrooms, or amanita phalloides, are responsible for more than 90 percent mushroom-related deaths worldwide. In the United States, this species of mushroom is primarily found in cool coastal regions on the west coast, as well as several areas in the mid-Atlantic and northeast, according to the CDC.
The CDC said foragers should be careful when collecting wild mushrooms and should always have a mycologist, or mushroom expert, examine them before eating.
The 14 people described in the report had either eaten wild mushrooms they'd picked or received from someone else.
The poisonings occurred during a two-week period in December of 2016. Around that time, members of the Bay Area Mycological Society notified personnel at the California Poison Control System that there was an unusually large bloom of "death cap" mushrooms in the greater San Fransico Bay area because of "abundant rainfall and recent warm weather."
"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 report noted.
In addition, researchers said the growing number of inexperienced foragers raises a risk for poisoning. Early symptoms of poisoning can include abdominal pain, nausea, vomiting, severe diarrhea and a fever.
The Associated Press contributed to this report.