According to a U.S. Centers for Disease Control and Prevention report released Friday 26 August, it took time for federal investigators to identify the source of a listeria outbreak ultimately linked to Dole’s Springfield facility, in part because it marked the first time a listeria outbreak was tied to leafy vegetables.
A standard questionnaire commonly used by investigators to gather information about foods consumed during an outbreak did not include leafy greens as an option when investigators questioned patients in November, the report said. Investigators eventually closed in on the source of the outbreak after interviewing those patients again in December and January, using open-ended questionnaires and reviewing shopping card records that were available.
“The Dole case was the first outbreak of listeria linked to leafy greens, but not the first illness connected to leafy greens,” said Brittany Behm, a spokeswoman for the CDC.
The CDC has since adjusted its listeria questionnaire to add questions about leafy greens for future cases, she said.
When patients were interviewed a second time, the report showed they reported eating leafy greens before becoming ill.
The outbreak affected at least 19 people in the U.S., including one person from Michigan who died. The CDC’s report Friday also noted one illness in a pregnant woman resulted in a preterm live birth, and one otherwise healthy child developed meningitis.
Officials from Dole did not respond to a request for comment Friday afternoon. Company officials have previously said they are cooperating with the U.S. Department of Justice, which has launched an investigation into the outbreak.