The U.S. Food and Drug Administration says tests did not detect Campylobacter in samples from a South Carolina raw milk dairy that public health investigators suspect made eight people ill in North Carolina.
All of those sickened — three people confirmed with campylobacteriosis and another five people who had probable infections — said they drank unpasteurized milk obtained via a courier from Tucker Adkins Dairy on June 14, the FDA said earlier this month. One person was hospitalized.
The FDA said milk from a June 14 sample was negative for the bacteria, which can cause bloody diarrhea and fever.
The negative lab test result does not rule out raw milk as the cause of the outbreak, according to the FDA. “The pathogen may have been in only one portion of the food. A sample taken from a portion that was not contaminated will have a negative test result,” said Stephanie Yao, of FDA’s Office of Public Affairs, in an email.
“The epidemiologic investigation implicated the raw milk as the cause of this outbreak,” Yao said.
This lack of a “smoking gun” is not unusual in foodborne illness investigations, and a negative test result on samples after the fact is not proof that a product was uncontaminated. One recent example: In the outbreak of E. coli O104:H4 in Europe, epidemiologic evidence points to sprouts sold to local restaurants and markets by a single farm as the source of nearly 4,000 illnesses, yet no sprouts or environmental samples from that grower tested positive for the outbreak pathogen.
The FDA’s Yao said the investigation into the outbreak of Campylobacter in South Carolina/North Carolina is ongoing.
The sale of unpasteurized milk is legal in South Carolina, and Tucker Adkins is licensed to sell raw milk within the state. The state of South Carolina inspects raw milk dairies monthly and tests for bacteria, although not for Campylobacter.
Under federal law, milk transported across state lines must first be pasteurized to protect the public health. The FDA says a courier was delivering Tucker Adkins raw milk twice a month to customers in North Carolina, where raw milk sales are not permitted by state law. There is no law against drinking raw milk: only retail sales are regulated.
In an interview with The Herald of Rock Hill, SC, Tucker Adkins dairy owner Carolyn Adkins said FDA officials investigating the Campylobacter outbreak asked for a list of her customers. She said she knew them by “their first name, by their prayer needs, by their family news,” but did not keep a list of last names or addresses. “This is a cash business,” she told the newspaper, which said Adkins sells raw milk for $6 a gallon. The dairy produces about 80 to 100 gallons of milk per day.