Thursday, February 16, 2012

Campylobacter and raw milk

Over 30 years ago as a young dairy veterinarian, I rambled through the Cumberland valley, near Chambersburg, PA, caring for cows in dairies such as the “The Family Cow”. Recently, this Southern Pennsylvania farm was linked to over 75 cases of campylobacteriosis in four states: Pennsylvania, Maryland, West Virginia, and New Jersey.  The outbreak ranks as one of Pennsylvania's three most severe raw milk outbreaks in the past five years.  This farm and many others in the area symbolize the local family farm ideal. So how can it be responsible for so much suffering?

Campylobacter is not the fault of the dairy farmer or the cow. Studies have shown that,on average 30%of fecal samples (Sato et al. 2004) and 9% of bulk tank samples test positive for Campylobacter (Jayaro and Henning, 2001). The bacterium lives happily in cattle, dogs and many other animals. However, in humans Campylobacter causes diarrhea (often bloody), abdominal pain, nausea, vomiting, and occasionally typhoid-like symptoms, including fever, anorexia, and headache. After infection, long term effects may include Guillian-Barré syndrome (which can cause paralysis) and arthritis (Heyman, 2004).

It boggles my mind that people come from Pittsburg, Philadelphia, and out of state to get their dose of diarrhea from the “Family Cow”. This farm sells 130,000 servings of raw (unpasteurized) milk per month, likely at a premium price. Pasteurization was/is one of the greatest food safety interventions ever implemented, besides cooking. Pasteurization would have prevented these and many other unreported illnesses.

My grandpa had a milk cow and I LOVED raw milk!  I likely was exposed to Campylobacter, but became accustomed to those particular strains. Thankfully, I never got tuberculosis, which was once the number one killer of young adults at the turn of the 20th century (Cramer and Frey, 2006). It was stopped by pasteurization, followed by the testing and removal of TB positive cattle. Many many years of research have gone into making the pasteurization process so that it does not alter the nutritional content of the milk, unless of course you want to keep the fecal bacteria.

Food safety officials and inspectors work constantly and frantically to prevent illness from a wide variety of bacteria and food sources. Why does society not let them solve this problem by requiring pasteurization In Pennsylvania, raw milk is labeled with a warning. But, I suppose anyone who is craving a good case of diarrhea will not take time to read the warning label. 

Additional reading and references

Campylobacter blog
Center for Disease Control and Prevention: Campylobacter

Cramer, D., Frey, R. 2006. Tuberculosis. Gale Encyclopedia of Medicine, 3rd edition. Available online at:
Food and Drug Administration. The Dangers of Raw Milk: Unpasteurized milk can pose a serious health risk.  <>

Heyman, D. 2004. Control of Communicable Diseases Manual. p. 81.

Jayaro, B.M, Henning, D.R. 2001. Prevalence of foodborne pathogens in bulk tank milk. J Dairy Sci. 84(10):2157-2162. Available online at: <>
Sato, K., Bartlett, P.C., Kaneene, J.B., Downes, F.P. 2004. Comparison of prevalence and antimicrobial susceptibilities of Campylobacter spp. isolates from organic and conventional dairy herds in Wisconsin.
Appl Environ Microbiol 70(3): 1442-1447. Available online at: <>