The health risks are particularly severe among the young, elderly, pregnant women and those with compromised immune systems.
Between 1993 and 2006 a total of 20 states reported 121 outbreaks caused by contaminated dairy products. Of these 73 percent involved non-pasteurized products and were caused by bacteria (CDC). The bacteria identified in raw milk or non-pasteurized dairy products outbreaks were: Campylobacter (54 percent), Salmonella (22 percent), Shiga-toxin producing Escherichia Coli (13 percent), Brucella (4 percent), Listeria (4 percent), and Shigella (3 percent). The MN Department of Health recently published an extensive (one decade) report on non-outbreak gastro-intestinal infections associated with raw milk (Robinson et al. 2013).
Main causative agents were: Campylobacter, Salmonella, Cryptosporidium, E. coli O157, and E. coli non-O157 with Campylobacter accounting for 77 percent of the cases. Results of this report concluded that sporadic illnesses associated with raw milk consumption far outnumber those reported as outbreaks by the Center for Disease Control (CDC). It also concluded that laboratory-confirmed infections are 25 times greater than reported outbreaks and that 17 percent of Minnesotans that consumed raw milk became ill during the duration of the study.
Campylobacter is the most common intestinal pathogen in Minnesota, with a yearly median of 903 cases between 2001 and 2008. In one of the biggest outbreaks of campylobacter bacteria seen nationally, raw milk from a Pennsylvania dairy sickened 148 people in four states in January 2012 (CDC).
Milk has become safer today than in the past as a result of better understanding of bacteria, improvements in cattle health, and the development of hygienic milk handling practices. However, the best we can do is just to reduce, not eliminate the risk of contamination. A cow producing 80 pounds of milk excretes nearly 100 pounds of wet feces, and no matter how careful dairy farmers are they cannot guarantee milk to be free from bacteria.
Not only does bacteria come from feces but also from infected udders (mastitis), dust, rodents, insects, dirty milking equipment, etc. Quickly, cooling raw milk in sanitary storage containers such as a bulk tank helps preserve it and minimize the growth of these bacteria to a certain extent. Once we drink it however, bacteria enter an environment (our digestive system) abundant in nutrients and optimum temperature for their growth. A fight then ensues between the body cells and the pathogens.
The body of a healthy adult might remember previous similar challenges (immunity) and be prepared to fight. However young children don’t have this acquired memory within their body cells (immunity), and the elderly have lost it or it’s weakened. After extensive studies on food and its safety, pasteurization was developed to protect the end consumer from harmful and sometimes fatal microorganisms that may haphazardly reach the food chain, while simultaneously protecting humans and young calves from unwanted diseases.
Robinson, T.J, J.M. Schefel, and K.E. Smith. 2013. Raw Milk Consumption Among Patients With Non-Outbreak-Related Enteric Infections. Minnesota Department Of Public Health, St. Paul. MN.