Investigation Update: Salmonella outbreak, Raw Cookie Dough - May 2023

Key points

This outbreak is over. But any raw cookie dough made with unpasteurized eggs or raw flour can have germs like Salmonella and E. coli. Always follow cookie dough baking instructions in the recipe or on the package label.

Papa Murphy’s Chocolate Chip Cookie Dough
Papa Murphy’s Chocolate Chip Cookie Dough

Latest update

July 13, 2023

CDC, public health and regulatory officials in several states, and the U.S. Food and Drug Administration (FDA) investigated a multistate outbreak of Salmonella Enteritidis infections.

Epidemiologic and traceback data showed that Papa Murphy's raw cookie dough made people sick.

As of July 13, this outbreak is over.

Epidemiologic and Traceback Data

A total of 26 people infected with the outbreak strain of Salmonella were reported from 6 states (see map). Illnesses started on dates ranging from February 24, 2023, to May 28, 2023 (see timeline). Of 23 people with information available, 4 were hospitalized. No deaths were reported.

The true number of sick people in this outbreak was likely much higher than the number reported, and the outbreak may not have been limited to the states with known illnesses. This is because many people recover without medical care and are not tested for Salmonella.

Public health officials collected many different types of information from sick people, including their age, race, ethnicity, other demographics, and the foods they ate in the week before they got sick. This information provided clues to help investigators identify the source of the outbreak.

The table below has information about sick people in this outbreak ("n" is the number of people with information available for each demographic).

Demographics
Information
Age
(n=26)
Range from 14 to 81 years
Median age of 48 years
Sex
(n=26)
81% female
19% male
Race
(n=23)
100% White
Ethnicity
(n=20)
100% non-Hispanic

State and local public health officials interviewed people about the foods they ate in the week before they got sick. Of the 22 people interviewed, 17 reported eating food from Papa Murphy's. Fifteen people ate Papa Murphy's raw chocolate chip cookie dough or raw S'mores bars dough, and one person ate baked cookies made with Papa Murphy's chocolate chip cookie dough.

Laboratory Data

Public health investigators used the PulseNet system to identify illnesses that were part of this outbreak. CDC PulseNet manages a national database of DNA fingerprints of bacteria that cause foodborne illnesses. DNA fingerprinting is performed on bacteria using a method called whole genome sequencing (WGS).

WGS showed that bacteria from sick people's samples are closely related genetically. This suggests that people in this outbreak got sick from the same food.

WGS analysis of bacteria from 26 people's samples did not predict resistance to any antibiotics. Standard antibiotic susceptibility testing of one person's sample by CDC's National Antimicrobial Resistance Monitoring System (NARMS) laboratory also showed no resistance.

Public Health Actions

On May 23, Papa Murphy's temporarily stopped selling their raw chocolate chip cookie dough and raw S'mores bars dough in response to this outbreak. As of July 13, Papa Murphy's has not restarted sales of cookie dough and is reviewing their dessert labels to make it clear to customers that their products are not intended to be eaten raw.

CDC always advises people not to eat raw cookie dough, unless it has a label indicating that it is safe to be eaten raw.