The study, published in the March CDC journal Emerging Infectious Diseases, reviewed dairy product outbreaks from 1993 to 2006 in all 50 states. The authors compared the amount of milk produced in the United States during the study period (about 2.7 trillion pounds) to the amount that CDC estimates was likely consumed raw (1 percent or 27 billion pounds) to determine the 150 times higher rate for outbreaks caused by raw milk products. Raw milk products include cheese and yogurt.
The study included 121 dairy–related disease outbreaks, which caused 4,413 illnesses, 239 hospitalizations and three deaths. In 60 percent of the outbreaks (73 outbreaks) state health officials determined raw milk products were the cause. Nearly all of the hospitalizations (200 of 239) were in those sickened in the raw milk outbreaks. These dairy-related outbreaks occurred in 30 states, and 75 percent (55 outbreaks) of the raw milk outbreaks occurred in the 21 states where it was legal to sell raw milk products at the time. The study also reported that seven states changed their laws during the study period.
The study also found that the raw milk product outbreaks led to much more severe illnesses, and disproportionately affected people under age 20. In the raw milk outbreaks with known age breakdowns, 60 percent of patients were younger than age 20, compared to 23 percent in outbreaks from pasteurized products. Children are more likely than adults to get seriously ill from the bacteria in raw milk.
Among other key findings:
- Thirteen percent of patients in raw milk outbreaks were hospitalized compared to 1 percent in pasteurized milk outbreaks. This may be because raw milk outbreaks were all caused by bacteria, such as E. coli O157, which tend to produce more severe illnesses, according to the study.
- Pasteurized milk and cheese outbreaks were often caused by relatively mild infections like norovirus and Staphylococcus aureus.