In early February 2012, the California Department of Public Health (CDPH), Food and Drug Branch (FDB) was notified by the CDPH Infectious Diseases Branch (IDB) about a cluster of California residents with Campylobacteriosis. All cases had exposure to raw (unpasteurized) milk. IDB determined that the majority of case patients had consumed Claravale Farms brand raw milk products during the period preceding their illnesses. A total of 22 cases of C. jejuni were reported to IDB over the course of this investigation. The age range of case patients was one to 66 years. Illness onset dates ranged from January 29, 2012 to April 9, 2012. Five Campylobacter isolates collected from cases that had exposure to Claravale Farms raw milk were a genetic match using Pulsed field gel electrophoresis (PFGE). These isolates also matched the PFGE patterns from the Claravale Farms raw cream samples collected by FDB and the California Department of Food and Agriculture (pattern designation DBRS16.0024/DBRK02.1142).
Samples of Claravale Farms raw whole milk were collected from four case patients who still had remaining product. Samples were tested for Campylobacter and Escherichia coli O157:H7. Campylobacter was not detected in any of the raw milk samples, however, two unopened bottles of raw whole milk tested positive for E. coli O157:H7. FDB initiated an environmental investigation at the dairy based on the positive findings.
On March 13 and 14, 2012, FDB investigators collected a total of 170 samples at Claravale Farms: 22 product (whole raw cow milk, nonfat raw cow milk, raw cow cream, and raw goat milk), 62 sponge swabs, 11 soil, 17 water, and 58 feces. Of the 22 product samples, one (raw cow cream) was positive for C. jejuni, and two (one whole and one nonfat raw cow milk) were positive for non-O157:H7 E. coli. The California Department of Food and Agriculture (CDFA) also was on-site and collected product samples from the dairy which were tested for standard plate count, coliforms, Campylobacter, Salmonella, E. coli O157:H7, and Listeria. One sample, raw cow cream, was positive for C. jejuni. This finding prompted CDFA to issue a statewide recall and quarantine order to Claravale Farms on March 23, 2012. This order prevented the dairy from selling all raw milk products, and necessitated the removal of their raw cow milk, raw non-fat cow milk, raw cow cream, and raw goat milk from retail locations. Claravale Farms had already ceased distribution on March 19, 2012 due to their knowledge of CDFA’s presumptive positive result of the raw cow cream sample. The firm ceased operations until the quarantine was lifted on March 29, 2012.
FDB and CDFA returned to Claravale Farms on April 23, 2012 due to additional Campylobacteriosis cases associated with raw milk from Claravale Farms subsequent to the CDFA quarantine release. Thirty one additional environmental samples were collected by FDB. C. jejuni was detected in one sample collected from a floor drain in the clean-in-place room. This sample did not match the outbreak strain.
CDPH’s environmental and epidemiological investigation indicated that raw whole cow milk manufactured by Claravale Farms was likely contaminated with C. jejuni that led to illness. Operational deficiencies were reported which could have contributed to contamination of the raw milk.