Four of 41 people infected have been hospitalized. Those sickened range in age from 2 to 74.
The dried wood ear mushrooms were sold directly to restaurants and not to consumers and were distributed by Wismettac Asian Foods, Inc. in Sante Fe Springs, California.
In interviews, ill people answered questions about the foods they ate and other exposures in the week before they became ill, the FDA said.
According to the CDC, of 18 people with information, 16 (89 percent) reported eating ramen at a restaurant in the week before their illness started.
Four illness clusters were identified at restaurants serving ramen in three states.
Eight (89 percent) of the nine ill people linked to restaurant clusters reported eating wood ear mushrooms or ramen containing wood ear mushrooms in the week before their illness started.
The product was distributed in six packs of five-pound bags to restaurants in 32 states, including New York, Connecticut, Massachusetts and New Jersey, as well as Canada.
For a map of states where illnesses have been reported, click here.
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