SACRAMENTO – Spoiled milk was likely responsible for an outbreak of gastroenteritis that sickened more than 1,300 inmates and 14 employees at 11 state prisons last month, officials said Friday.
The inmates and employees had symptoms between May 16 and 26 that included fever, headaches, diarrhea, cramping and vomiting caused by campylobacter, a bacteria.
Investigators were never able to find the bacteria in food and milk samples, and they said milk processing equipment tested clean at the Deuel Vocational Institution farm in Tracy, which supplied milk to the 11 prisons.
But milk was “the only food item that had any significant connection” among the sick inmates, said Dr. Mark Starr of the California Department of Health Services. “It was quite a dramatic difference.”
Those who consumed milk were 11 times more likely to have symptoms, he said.
The animal-borne bacteria is commonly spread to humans through meats or animal-contaminated milk or water.
Dr. Stephen Beam, chief of the milk and food safety branch of the California Department of Food and Agriculture, speculated that contaminated containers, packaging equipment or holding tanks may have been the problem, as the farm’s pasteurization process and other procedures met health standards.
California Department of Corrections and Rehabilitation’s acting secretary, James E. Tilton, said there was no evidence of human tampering. A few inmates were treated at prison infirmaries, but most were treated in their cells.
“The outbreak seems to be over,” and the public was never affected, he said.
Dairy production was shut down for a few hours for inspection May 19, and 25,000 half-pint containers of milk produced May 8-18 were recalled and destroyed. Milk containers during that period had a higher bacteria count, Beam said, but the bacteria could not be identified.
The farm at Deuel produces about 6,000 gallons of raw milk each day. It is one of three prison dairies that employ about 300 inmates and supply milk to all but three of the state’s prisons.