Five California boys found with genetically matching E. coli O157:H7 infections in the fall of 2011 have been conclusively linked to raw milk produced by Organic Pastures, a Fresno dairy, according to a report published Monday by the California Department of Public Health.

Following an investigation by the state health department and the California Department of Food and Agriculture, public health investigators concluded that Organic Pastures raw milk was the only common exposure between the five boys, who each drank it within the week prior to falling ill.

Raw milk is milk that has not been pasteurized to eliminate harmful pathogens from cow excrement, such as E. coli O157:H7 and Campylobacter, which may contaminate fresh milk.

Environmental samples from the dairy detected E. coli that was genetically identical to the five children’s infections. According to the report, the particular E. coli type in the outbreak is uncommon in California and had not been seen in the state since January 2010.

Three of the boys were hospitalized with hemolytic uremic syndrome (HUS), a potentially deadly disease characterized by the destruction of red blood cells and acute kidney failure. The five victims were residents of four separate counties: Contra Costa (2 brothers), Kings (1), Sacramento (1) and San Diego (1). They ranged in age from one to five years old, with a median age of four. 

The investigators compared the boys’ infections with 47 other cases of E. coli O157:H7 infection in young children with illness onsets in the same timeframe. They found that raw milk was much more closely associated with the five boys whose infections matched the Organic Pastures samples. In fact, none of the other 47 children with E. coli infections had consumed raw milk within a week of becoming ill.

Given that only approximately three percent of Californians drink raw milk, the report explains, the probability of all five victims consuming raw milk is less than one in 10 million.

The report cites a 2006 E. coli O157:H7 outbreak linked to Organic Pastures raw milk or raw colostrum that sickened six children. The dairy has previously initiated recalls of its raw milk products after detecting Campylobacter and Listeria monocytogenes in samples.

The report also noted that there might have been additional E. coli infections from the same lot of Organic Pastures raw milk that went undiagnosed and unreported. By the time the health department initiated its investigation, there were no remaining samples of milk from that lot available to test, as it had all expired or been consumed.

“Nonetheless, data from the epidemiologic, laboratory and environmental investigations strongly implicate Organic Pastures raw milk as the source of the illnesses,” the report stated.

In November 2011, California State Veterinarian Dr. Annette Whiteford announced a statewide recall of all Organic Pastures raw milk products, with the exception of cheese aged to at least 60 days. The dairy was then placed on a quarantine order and not allowed to produce raw milk for retail for 30 days.

Health department officials inspected the dairy and found a number of sanitation problems, including poor equipment maintenance for preventing contamination, rodent droppings and flies in milk storage rooms, and colostrum buckets overturned onto cardboard lying on the floor.

Following the November 2011 outbreak, the state department of health forced Organic Pastures to discontinue production of its raw colostrum permanently, even though that product was not being suspected of causing the outbreak.

The health department’s report concluded by offering support to public education efforts regarding the risks of raw milk consumption. Children, pregnant women, the elderly and those with weakened immune systems are most susceptible to the bacteria that may contaminate iraw milk.

A full environmental investigation report on Organic Pastures’ facility is still forthcoming.