The strain of E. coli that caused nine children to become ill after drinking raw milk obtained from McBee Dairy Farm near Knoxville, Tenn., has been matched to animal waste collected at the dairy, according to a Thursday press release from the Tennessee Health Department.

Five of the nine children, all younger than seven, required hospitalization, and three developed a severe kidney problem known as hemolytic uremic syndrome.

The department’s investigation involved an on-site inspection of the farm (McBee Dairy Farm), interviews of 88 households that purchased milk from the farm, and laboratory analysis of samples and materials to compare bacterial strains. Officials from the Knox County Health Department have also been involved in the investigation and patient outreach efforts.

“This outbreak points out, again, the serious risks associated with drinking unpasteurized or ‘raw’ milk,” said TDH Commissioner John Dreyzehner, M.D., MPH. “While people with stronger immune systems may be able to overcome the bacteria found in raw milk, children, older people, pregnant women and those with health conditions can be seriously harmed by bacteria in non-pasteurized milk products and should not consume them.”

“Milk from the healthiest-appearing cows in the cleanest dairy operations can still contain deadly microorganisms,” said TDH State Epidemiologist Tim Jones, M.D. “Pasteurization, which simply involves heating the milk, kills these microorganisms and leaves the healthy nutrients. Those who consume raw milk are playing Russian roulette with their health; the glass they drink today may not have deadly microorganisms, but the one they drink tomorrow may cause serious health problems or even death.”

The McBee Dairy Farm operates a cowshare program in which the customers own shares in the cows and therefore also own the milk. Under this sort of arrangement, which state officials refer to as a “legal loophole,” the dairy is technically not selling the milk.