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Increase in Outbreaks Associated with Nonpasteurized Milk, United States, 2007-2012

New Publication

  Emerging Infectious Diseases Journal - Volume 21, Number 1—January 2015
Volume 21, Number 1—January 2015 
Increase in Outbreaks Associated with Nonpasteurized Milk, United States, 2007-2012 [PDF - 4 pages]

The  number of outbreaks in the United States caused by nonpasteurized (raw) milk  increased from 30 in 2007-2009 to 51 in 2010-2012.  Most (77%) outbreaks were caused by Campylobacter and most (81%) occurred  from consumption of nonpasteurized milk purchased from states where the sale of  nonpasteurized milk was legal. 

Questions and Answers

What is this study about?

  • This study reviewed outbreaks caused by raw milk–milk that has not been pasteurized to kill disease-causing germs –in the United States that were reported to CDC from 2007-2012.
  • The study analyzed the number of outbreaks, the legal status of raw milk sales in each state, and the number of illnesses, hospitalizations, and deaths associated with these outbreaks.

What did the study show?

The number of outbreaks caused by raw milk has increased.

  • From 2007-2012, 26 states reported 81 outbreaks caused by raw milk to CDC. These outbreaks caused 979 illnesses and 73 hospitalizations.
    • From 2007-2009, 30 outbreaks were linked to raw milk. This increased to 51 outbreaks from 2010-2012.
  • Among outbreaks in which the food causing the outbreak was identified, the percentage caused by raw milk increased from 2% in 2007-2009 to 5% in 2010-2012.
  • Three germs caused most raw milk outbreaks from 2007-2012:
  • The average number of outbreaks caused by raw milk each year was 4 times higher from 2007-2012 than from 1993-2006.

Children were at the highest risk for illness from raw milk.

  • 59% of outbreaks involved at least 1 child younger than 5.
  • 38% of illnesses caused by Salmonella and 28% of illnesses caused by Shiga toxin-producing E. coli were among children ages 1-4.

Common germs and number of outbreaks associated with raw milk from 2007-2012.

Graph: Common germs and number of outbreaks associated with raw milk from 2007-2012

More states are legalizing the sale of raw milk even though this leads to an increase in the number outbreaks.

  • 81% of outbreaks were reported in states where the sale of raw milk was legal.
  • In 2004, there were 22 states where the sale of raw milk was legal in some form; however, this number increased to 30 in 2011.
  • The number of states allowing cow-share programs –in which a person buys part ownership of a cow in return for the milk produced –increased from 5 in 2004 to 10 in 2008.

Where do people buy raw milk?

Dairy farms: farms that keep cows for the purpose of milk production

Licensed/commercial sellers: farms or store fronts separate from a farm

Cow share or herd share: buyers pay farmers a fee to care for a cow in exchange for a percentage of the milk that is produced

Buying club: a group of individuals that gather to purchase food (including dairy products) from farmers at discounted prices

Raw milk sales in one state can lead to outbreaks in neighboring states.

  • The raw milk that caused outbreaks came from:
    • The dairy farm directly 71% of the time
    • Licensed or commercial milk sellers 13% of the time
    • A cow share or herd share 12% of the time
  • Although raw milk is not included in interstate commerce (across state lines), some states do allow sales with varying degrees of restriction.
  • In a 2011 outbreak of Campylobacter infections in North Carolina, where sales were prohibited, raw milk was purchased from a “buying club” in South Carolina where sales were legal.
  • In a 2012 outbreak of Campylobacter infections in Pennsylvania, where raw milk sales were legal, cases were reported from Maryland, West Virginia, and New Jersey, where sales were prohibited.

Why is this study important?

Outbreaks from raw milk continue to pose a public health challenge.

  • Consumers should only consume pasteurized milk and milk products. Look for the word "pasteurized" on product labels.
  • Public health officials can continue to educate the public about the dangers related to consuming raw milk.
  • Federal and state regulators can enforce existing regulations to prevent the distribution of raw milk.

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