As detailed in their study, which was published in the journal Emerging Infectious Diseases, CDC researchers reviewed all US foodborne outbreaks between 2007 and 2012 in which the "food vehicle" was unpasteurized milk.
During the six-year period, 81 outbreaks across 26 US states, which resulted 979 illnesses, 73 cases of hospitalization, but no deaths, were attributed to raw milk consumption.
Compared with the period 1993 to 2006, the average number of raw milk-related outbreaks "more than quadrupled" from 3.3 per year to 13.5 between 2007 and 2012.
“As more states have allowed the legal sales of raw milk, there has been a rapid increase in the number of raw milk associated outbreaks,” CDC said in an accompanying statement.
The US Food and Drug Administration (FDA) currently prohibits the interstate sale of unpasteurized milk for human consumption.
But an increasing number of US states permit the sale of raw milk in some form within state lines.
“Since 2004, eight additional states have begun allowing the sale of raw milk, bringing the number of states where raw milk sales are legal to 30.”
“At least five additional states allow cow shares – practice where people can pay a fee for a cow’s care in return for some of the cow’s raw milk – for a total of 10 states as of the most recent survey.”
“If more states begin allowing sales of raw milk, the number of outbreaks and illnesses will continue to rise," it predicted.
"Public health challenge"
Of the 81 raw milk-related outbreaks recorded between 2007 and 2012, Campylobacter was responsible for 62 (81%).
Shiga toxin producing E.coli (STEC) was to blame for 13 (17%), Salmonella enterica for two (3%), and Coxiella burnetii for one (1%).
The three remaining outbreaks were caused by multiple pathogens.
Sixty-six of the 81 outbreaks were reported in US states where the sale of raw milk was legal in some form.
The other 15 outbreaks were reported in eight states where sales were prohibited.
An increase in the number of raw milk-related outbreaks was also evident in this period.
Thirty US raw milk-related foodborne outbreaks (2% of all that implicated food) were recorded in 2007, 2008 and 2009.
Between 2010 and 2012, 51 outbreaks were attributed to raw milk - 5% of the total number.
On the back of its findings, CDC has called on lawmakers to consider the "dangers."
"Outbreaks associated with non-pasteurized milk continue to pose a public health challenge. Legalization of the sale of non-pasteurized milk in additional states would probably lead to more outbreaks and illnesses," the study concluded.
"Public health officials should continue to educate legislators and consumers about the dangers associated with consuming non-pasteurized milk."
"In addition, federal and state regulators should enforce existing regulations to prevent distribution of non-pasteurized milk," it added.
Source: Emerging Infectious Diseases http://wwwnc.cdc.gov/eid/article/21/1/14-0447_article
Title: Increased Outbreaks Associated with Non-pasteurized Milk, United States, 2007-2012
Authors: Elizabeth Mungai, Casey Barton Behravesh, L Hannah Gould