Tennessee Department of Health Identifies Source of Shiga Toxin-Producing E. coli O157:H7 as Whispering Willow Farm and Dairy, in Thompson’s Station, Tennessee
In May of 2024, the Tennessee Department of Health (TDH) Foodborne and Enteric Diseases (FED) Program identified a pediatric case of Shiga toxin-producing Escherichia coli (STEC) O157:H7 in a child from Tennessee. The case’s epidemiological investigation revealed exposure to raw cow’s milk obtained through a herd-share agreement with Whispering Willow Farm and Dairy, located in Thompson’s Station, Tennessee. This exposure prompted the immediate initiation of an outbreak investigation that eventually identified at least 13 victims.
Epidemiological Investigation
Whispering Willow Farm is a private operation that claims it sells raw cow and goat milk, cheese, yogurt, eggs, rabbits, and chickens through herd-share agreements—a legal exception to an outright ban on the sale of raw milk products in Tennessee under which customers become partial owners of a dairy animal and are thus allowed to consume its raw milk. While these herd-share agreements are legal under Tennessee law (T.C.A. § 53-3-119), they present a public health concern due to the known risks associated with raw milk consumption. As such, they have very specific requirements that , in this case, it is alleged Whispering Willow failed to follow.
As part of its investigation, the FED team contacted Whispering Willow Farm on May 23, 2024, and requested their herd-share membership list. It appears that the records were not maintained as mandated. In addition, the farm reported no prior knowledge of illnesses at that time. A questionnaire was developed using REDCap and distributed to 186 members on June 3, 2024. Whispering Willow was also ordered to cease production of goat and cow milk on that day.
The case definition used in the investigation was as follows:
- Confirmed Case: A person who consumed or had access to raw milk from Whispering Willow Farm on or after a specific date and tested positive for STEC O157:H7.
- Probable Case: A person who consumed or accessed raw milk from Whispering Willow and developed symptoms consistent with STEC infection (e.g., ≥3 loose stools in 24 hours) on or after the designated date.
- Confirmed Secondary Case: An individual who did not consume the raw milk but was in contact with a confirmed/probable case and tested positive for STEC O157:H7.
Environmental and Laboratory Findings
During the investigation, composite fecal samples from cattle and goats, as well as individual rectal swabs from cows at Whispering Willow, tested positive for STEC O157:H7. Of 36 environmental swabs, at least 11 returned positive for E. Coli O157:H7. Whole genome sequencing confirmed a high degree of genetic relatedness between these animal-derived isolates and clinical isolates from patients, pointing to a common source of infection.
This finding supports the conclusion that both cattle and goats at Whispering Willow Farm were colonized and actively shedding the pathogen. The contamination of raw milk likely resulted from a combination of environmental exposure pathways—such as feces on hides, flies, contaminated milking equipment, and other unsanitary farm conditions.
Previous Outbreaks Linked to Raw Milk in Tennessee
This outbreak of STEC illnesses linked to raw milk in Tennessee follows a 2018 incident that hospitalized four young children and a 2022 outbreak that resulted in Hemolytic Uremic Syndrome (HUS) in an infant.
Whispering Willow’s owners have also admitted family illnesses linked to consumption of raw milk.
Nationally, unpasteurized dairy products have been associated with 840 times more illnesses and 45 times more hospitalizations than pasteurized dairy products. The risk is especially high for children under five, the elderly, and the immunocompromised.
Despite Tennessee’s legal framework allowing herd-share arrangements, TDH emphasizes that pasteurization is essential for eliminating harmful pathogens. And although Whispering Willow Farm complied with TDH’s requests to halt raw milk distribution during the investigation, provide a member list, and submit to environmental testing, it did not provide the mandated warnings that are essential to the proper function of a herd share arrangement.
Secondary Transmission and Underreporting – Final Number of Victims Unclear
As the investigation unfolded, it also identified instances of secondary transmission, indicating that even those who did not directly consume the raw milk became ill through contact with infected individuals. And while 13 victims were identified, the true scope of the outbreak remains uncertain due to a low response rate (approximately 30%) to the outbreak questionnaire, underreporting of self-limiting illnesses, and lack of laboratory confirmation for all symptomatic individuals.
