We have recently seen a small number of illnesses and two deaths due to Listeria in the US. The vector is believed to be cheese manufactured from raw milk. This has reinvigorated debate about the general safety of raw milk and the benefits – or lack thereof – of drinking raw vs pasteurized milk. (Some argue that the best option is to drink no milk…) I haven’t given much thought to raw milk; I don’t drink it or eat raw-milk cheese (to my knowledge). But this recent event caused me to wonder whether raw milk is particularly bad compared to other vectors for food-borne illness.
The short answer is: it’s hard to be certain.
The CDC is a staunch anti-raw milk advocate, primarily on the basis that pasteurization kills the pathogens that lead to most known food-borne illnesses. They are also very certain that raw milk does not provide any nutritional benefit, though some debate that claim. After reading some of the data provided by the CDC, two things are evident: there are a large number of assumptions and estimates that go into their calculations, and; based on their data over 80% of food-borne illnesses are of unknown cause. That’s a sizable bit of not knowing.
It is also tricky business to determine the precise vector of a given pathogen, unless it results in a significant outbreak of disease. Even then it can be tricky, especially for pathogens such as Listeria, which can withstand cooling and freezing, and which can take weeks or even months to cause any recognizable symptoms. And while Listeria outbreaks have been linked to raw milk recently and soft cheeses in previous outbreaks, they have also been associated with produce, deli meats, hot dogs, and even Blue Bell ice cream (using pasteurized milk).
Listeria is particularly concerning due to its high rate of death upon infection, but it does not independently cause the majority of illnesses and deaths. The CDC estimates 1600 Listeria cases annually in the US out of 76 million food-borne illnesses. Of course, Listeria isn’t the only pathogen that raw milk can carry. The CDC tracked an increase in illness attributable to raw milk between 2007 and 2012, where raw milk was the vector in 2% of identified illnesses from 2007 to 200 and 5% between 2010 and 2012, and during this period Listeria was not the top pathogen. The pathogens in raw milk tracked by the CDC were Campylobacter, E. Coli, and Salmonella causing 81%, 17%, and 3% of cases respectively (for a total of 101%??).
Considering that under 20% of illnesses are identified, and that 5% (based on the 2012 data) of those 20% of cases are attributable to raw milk, it’s difficult to make a strong case that raw milk is inherently more dangerous than other vectors. Raw milk doesn’t normally just come from the udder with pathogens; they come from somewhere else and are introduced through improper handling. In all cases, improper food handling is the real culprit behind food-borne illnesses. I think raw milk gets targeted because you really can’t wash milk to get rid of a germ; that’s why pasteurization is recommended. But, even pasteurization of milk does not ensure that a milk product will not be contaminated. (Such as in the Blue Bell incident…)
In summary, avoid milk; drink beer.
*Below are the things I read that drove this bit of writing. I am feeling a little under the weather tonight, so I’m not putting the links in the text. Please forgive me. Or don’t. I’m still leaving it this way.