On October 18, 2023, an investigation of an outbreak associated with Raw Farm, LLC products was initiated. At least eight Salmonella cases who had reported consuming raw milk from Raw Farm, LLC of Fresno County, California, were discovered and reported to the California Department of Public Health (CDPH). Another nine cases from another county were discovered to be infected with Salmonella Typhimurium. Local health departments, CDPH, and the California Department of Food and Agriculture (CDFA) investigated this outbreak. This outbreak was assigned the CDC ID 2310MLJPX-2.

For this investigation, a confirmed case was defined as a laboratory confirmed infection of S. Typhimurium, within 2 alleles of code SALM1.0 – 6745.4.2.1x, that was highly related (within 4 SNPs) based on whole-genome sequencing (WGS) to the outbreak strain in a person with symptom onset since September 15, 2023. A probable case was defined as a laboratory-confirmed Salmonella infection, in a person who reported consumption of Raw Farm raw milk and had symptom onset since September 15, 2023.

As of February 12, 2024, 165 cases have been reported from four states: CA (162), NM (1), WA (1), and PA (1). Illness onsets ranged from September 21 to December 20, 2023. Symptoms included fever, bloody or watery diarrhea, nausea, vomiting, and headache. The age range of cases was <1 to 87 years (median 7). Sixty-five percent of cases were male. Twenty cases (14%) were known to require hospitalization; no deaths were reported. Four cases were discovered to have co-infections with S. Typhimurium and Campylobacter and/or STEC.

All cases who met the confirmed case definition, regardless of raw milk exposure, and all cases who met the probable case definition were also interviewed with a raw dairy supplemental questionnaire to ascertain the brand and purchase location of their exposure and whether they had any leftover product, along with any other details of raw dairy exposures prior to illness onset. Seventy-two percent (91/127) of cases reported consuming raw milk in the initial and/or supplemental questionnaire. Eighty-five percent (46/54) of California cases, in interviews with the supplemental questionnaire, reported consuming raw milk. Of those who consumed raw milk and recalled brand information, 93% (41/44) consumed Raw Farm brand raw milk. 

The proportion of confirmed patients who reported raw milk consumption during the week prior to illness was significantly higher (binomial p-value <0.001) than expected by chance alone, compared to the estimated 1.9% background rate of raw milk consumption during the prior week based on 2018 and 2019 FoodNet CA population survey estimates. All five patients who reported consuming or likely consumed other types of raw dairy products (including various cheeses, cream, and butter) also confirmed drinking Raw Farm raw milk.

Based on epidemiologic, laboratory, and traceback investigations conducted by local and state officials that indicated that raw milk consumed by cases was produced at Raw Farm, Raw Farm, LLC recalled their raw milk and raw heavy cream on October 24, 2023, including products with best by dates from October 11, 2023 to November 6, 2023. Products were sold at the following locations: Bristol Farm, Clark’s Nutrition, Elliott’s Natural Foods, Erewhon Market, Frazier Farm Market, Jimbo’s, Lassen’s Natural Foods, Lazy Acres, Lunardi’s, Mother’s Market, Nugget Market, and Sprouts Farmers Market locations. Specifically, the recalled products included the Raw Whole Milk in a gallon container (128 ounce) with item number 1000 and the barcode 835204006004, the Raw Whole Milk in half gallon (64 ounce) container with item number 1005 and the barcode 835204000095, the Raw Whole Milk in quart containers (32 ounce) with item number 1010 and the barcode 835204000019, and Raw Heavy Cream in 16 ounce containers with item number 3050 and the barcode 835204000132.

Beginning October 19, 2023, the CDPH, CDFA, and local health departments collected Raw Farm product samples (raw milk, cream, kefir and cheese) from the Raw Farm dairy, retail stores, and patients’ homes. Samples were tested for Salmonella and underwent WGS if positive. A total of four samples were found to be positive for the outbreak strain: A sample of raw milk collected by CDFA at the Raw Farm dairy in Fresno, CA on October 19, 2023, was found to be positive for S. Typhimurium matching the outbreak strain; Another sample from the Raw Farm dairy, collected by CDFA on October 25, 2023, was also positive for the outbreak strain of S. Typhimurium; One other sample collected on an unknown date from the dairy farm was also found to be positive for the outbreak strain; One retail sample of raw milk in a 64 oz. container with a best by date of 10/27/2023 tested positive for the outbreak strain of S. Typhimurium. The remaining samples from retail stores and patients’ homes were negative for Salmonella. 

Epidemiologic, laboratory, and traceback investigations have identified Raw Farm brand raw (unpasteurized) milk as the source of this outbreak. The investigation was ongoing as of February 2024.

Dairy products from Raw Farm LLC in Fresno, CA were previously recalled in May 2023 following detection of Campylobacter, and later recalled in August 2023 due to Salmonella in cheese products. A plethora of other outbreaks (STEC O157, STEC O103, Campylobacter) associated with Raw Farm products have been detected since 2006.