At least ten individuals suffered severe botulism illnesses, with one death, after consuming cheese sauce contaminated with C. botulinum from the Valley Oak Food and Fuel Company store (VOFF) located at 14165 River Road in Walnut Grove, California.
All individuals ultimately tested positive for the C. botulinum bacteria. The California Department of Public Health (CDPH) collaborated with the Sacramento County Public Health (SCPH), the Sacramento County Environmental Management Department (SCEMD), the FDA, the CDC, and other local county public health agencies to investigate the outbreak of botulism illnesses during the months of April and May 2017. The government’s efforts eventually deemed all victims as confirmed cases in the outbreak after identifying the presence C. botulinum toxin type A.
Upon learning that nacho cheese from VOFF was a common food item amongst all interviewed illness cases, health officials conducted an environmental investigation of VOFF in hopes of determining the source of botulism. SCPH and SCEMD impounded a Gehl’s cheese sauce dispenser and an opened bag of Gehl’s Jalapeno cheese sauce with a “Best By” date of “11APR2017” found inside the dispenser. The bag of cheese sauce and dried cheese scrapings collected from inside the cheese dispenser tested presumptive positive for C. botulinum toxin type A and the cheese sauce was later confirmed positive for C. botulinum toxin type A by the CDPH Microbial Diseases Laboratory. Other items collected from VOFF—including an unopened bag of cheese sauce with an expiration date of “DEC2017” and 15 environmental samples—were all negative for the botulism toxin.
Investigating officials also discovered multiple issues surrounding the operation of the cheese sauce dispenser that could have led to the botulism contamination. The opened bag of cheese sauce that tested positive for C. botulinum toxin was being used by VOFF past the “Best By” date of April 11, 2017 and at a temperature of 111ºF—significantly lower than both the manufacturer’s suggested minimum holding temperature of 140ºF and the required holding temperature per the California Retail Food Code of 135ºF. VOFF employees stated that they did not conduct any manual temperature checks, nor did they document replacement dates of the cheese sauce.
Upon further investigation, health officials discovered that many of the operation instructions provided on the cheese sauce packaging and on the cheese dispenser unit were not being followed by VOFF employees. Specifically, VOFF lacked the appropriate tool to open the bags of cheese sauce, did not take temperatures of the cheese sauce to ensure appropriate hot-hold temperatures were maintained, and did not have any records to indicate the bags of cheese sauce were changed at least once every five days. Further, the valve guard was not installed on the dispenser, which possibly caused temperatures to fall below the recommended 140ºF. Despite the multiple failures, the investigating officials were unable to determine a precise method of contamination.