Food-borne Pathogenic Bacteria & Milk

Source – Wikimedia. Licensed under Creative Commons

In my initial reading on the controversial science topic of ‘raw’ milk (debate, consumption, movement), the risk of contracting food-borne pathogenic bacteria featured prominently. In one of my first posts on the ‘raw’ milk controversy – Raw Milk & Pasteurisation, I posed a few questions that I wished to answer. Until now I haven’t delved too deep into these questions (I briefly touched on the risk of contracting a food-borne illness from consuming ‘raw’ milk in my post – Risk Assessment of ‘Raw’ Cow Milk in Australia last week). These unanswered questions are –

• If ‘raw’ milk is unpasteurised, are pathogenic bacteria such as Campylobacter jejuni, Salmonella species and Escherichia coli (E. coli) present in ‘raw’ milk?
• And what risk does drinking ‘raw’ milk pose?
• Are you likely to suffer food poisoning from drinking ‘raw’ milk?

Pathogenic bacteria isolated from ‘raw’ milk may include Salmonella species Campylobacter species, Listeria monocytogenes and E.coli, aetiological agents of gastroenteritis and more serious complications such Haemolytic Uremic Syndrome (which can lead to kidney failure) and Guillian-Barre Syndrome (a form of flaccid paralysis) (CDC, 2014a and Foodsafety.gov).

The Centers of Disease Control (2014) states that individuals are 150 more times likely to contract a food-borne illness from ‘raw’ milk than pasteurised milk. Unpasteurised milk results in 13 times more hospitalisations than illnesses involving pasteurised dairy products.

In a epidemiological study of disease outbreaks contracted from unpasteurised dairy products from 1993 to 2006 (Nonpasteurised Dairy Products, Disease Outbreaks, and State Laws – United States, 1993 – 2006), the CDC reported that of 121 outbreaks due to dairy products reported to the CDC, 73 (60%) outbreaks were caused by ‘raw’ milk (CDC, 2014b). To directly quote the CDC –

“Probably no more than 1% of the milk consumed in the United States is raw, yet more outbreaks were caused by raw milk than by pasteurised milk. If you consider the number of outbreaks caused by raw milk in light of the very small amount of milk that is consumed raw, the risk of outbreaks caused by raw milk is at least 150 times greater than the risk of outbreaks caused by pasteurised milk.”

The CDC also reported in this article that the hospitalisation rate for patients in outbreaks caused by raw milk was 13 times higher (13% vs. 1%) than the rate for people in outbreaks caused by pasteurised milk, likely due to outbreaks from ‘raw’ milk being caused by bacteria that cause more severe illnesses, such as E. coli o157:H7 (CDC, 2014b).

As a follow on from the CDC report described above, James Andrews at Food Safety News reported in 2012 that – “Since January 2007, the end of the study’s review window, there have been at least 56 additional food-borne illness outbreaks associated with raw milk. Between 2010 and 2011, raw dairy products were linked to 21 outbreaks and 201 illnesses, while pasteurised dairy products caused two outbreaks and 39 illnesses.”

‘Raw’ dairy products are linked to more food-borne illness outbreaks than pasteurised dairy products. And only a small proportion of the United States population consumes ‘raw’ dairy products. How do the numbers of food-borne illness outbreaks linked to dairy products (pasteurised and unpasteurised) compare to those caused by other food sources such as poultry, beef, shellfish and vegetables?

A CDC report on food-borne disease outbreaks in the United States from 1998 to 2008 by Gould et al, 2013 (Surveillance for Foodborne Disease Outbreaks — United States, 1998–2008, summarised on the Surveillance for Foodborne Disease Outbreaks – United States, 1998-2008 webpage) reported that the most common commodities implicated in food-borne illness outbreaks for which a food vehicle could be assigned (3,264 outbreaks) were poultry (19%), fish (19%) and beef (12%). Dairy products (presumably pasteurised and unpasteurised (‘raw’) dairy products) were implicated in about 6% of outbreaks (Gould et al, 2013). The percentage of outbreaks associated with dairy products increased from 4% of outbreaks in 1998 – 1999 to 7% during 2006 – 2008 (CDC, 2013). Interestingly, the CDC states that the increase in the number of outbreaks caused by dairy products is due to an increase in the number of outbreaks caused by unpasteurised (‘raw’) milk (CDC, 2013).

The CDC, on the website summarising the surveillance report,  reports states that “leafy vegetables, poultry, beef, and foods in the category that contains fruits and nuts were responsible for the most outbreak-associated illnesses.” In the surveillance report itself, Gould et al state that dairy products (and other food commodities such as fruits/nuts and vine-stalk vegetables) contribute to a relatively larger percentage of illnesses than outbreaks, and based on the percentage of outbreak-related illnesses associated with each commodity, analysis attributed the majority of foodborne illnesses to leafy vegetables, dairy, fruits/nuts, and poultry.

In conclusion, according to CDC statistics, someone is a lot more likely to contract a food-borne illness (caused by pathogenic bacteria such as E. coli, Campylobacter or Salmonella species) from unpasteurised (‘raw’) dairy products, than pasteurised dairy products.

Dear readers, would you drink ‘raw’ milk given these statistics?

References

Andrews, James (2012). CDC: Raw Milk Much More Likely to Cause Illness. Food Safety News. Retrieved 26 October 2014 from http://www.foodsafetynews.com/2012/02/cdc-raw-milk-much-more-likely-to-cause-illness/#.VExl4r7N78s

Centers for Disease Control. (2013). Surveillance for Foodborne Disease Outbreaks – United States, 1998-2008. Retrieved 26 October 2014 from http://www.cdc.gov/foodsafety/fdoss/data/annual-summaries/mmwr-questions-and-answers-1998-2008.html

CDC report summarised by CDC 2013 – Gould, L. H., Walsh, K. A., Vieira, A. R., Herman, K., Williams, I. T., Hall, A. J. & Cole, D. (2013). Surveillance for Foodborne Disease Outbreaks — United States, 1998–2008. Surveillance Summaries. 62(SS01), 1-34. Retrieved 26 October 2014 from http://www.cdc.gov/mmwr/preview/mmwrhtml/ss6202a1.htm?s_cid=ss6202a1_w

Centers for Disease Control. (2014a). Raw Milk Questions and Answers. Retrieved 21 August 2014 from http://www.cdc.gov/foodsafety/rawmilk/raw-milk-questions-and-answers.html,

Centers for Disease Control. (2014b). Nonpasteurized Disease Outbreaks, 1993-2006. Retrieved 26 October 2014 from http://www.cdc.gov/foodsafety/rawmilk/nonpasteurized-outbreaks.html

CDC Report – summarised by CDC, 2014b – Langer, A. J., Ayers, T., Grass, J., Lynch, M., Angulo, F. J. and Mahon, B. E. (2012) Nonpasteurized Dairy Products, Disease Outbreaks, and State Laws—United States, 1993–2006. Emerging Infectious Diseases 18(3). 386 – 391. retrieved 26 October 2014 from http://wwwnc.cdc.gov/eid/article/18/3/pdfs/11-1370.pdf

Foodsafety.gov – Milk, Cheese, and Dairy Products – Myths About Raw Milk. Retrieved 26 October 2014 from http://www.foodsafety.gov/keep/types/milk/index.html

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Thoughts on Dairy Farming & Milk Processing

In my post The ‘Raw’ Milk Controversy from September I touched the key elements involved in the controversy around ‘raw’ milk. One element in the controversy that I haven’t discussed so far is –

Industry – Animal Husbandry & Food Manufacturing 

• Modern animal husbandry and dairy-farming practises
• Mass production and increased risk of contamination of animal products
• Pasteurisation as standard practise in the dairy industry
• An industry driven by greed and profit VS organic farming techniques; small-scale farming with better conditions for dairy cattle; more traditional methods; and support for local farmers

I’m not qualified nor very knowledgeable on dairy-farming or milk processing techniques, but I have been wondering if the following may have changed the taste, quality and safety of milk, and thus influence consumers to seek out ‘raw’ milk for consumption –

• Modern dairy-farming and animal husbandry practises
  • Certain breeds of cows (milk sourced from only a few breeds)
  • Cows being grain fed
  • Use of antibiotics and prophylactics
  • The rise of pathogenic strains of bacterial species such as E. coli 0157:H7
• Modern milk processing practises
  • Mixing of milk from multiple herds
  • Pasteurisation
  • Homogenisation
  • Fortification

And do the following choices / options also influence consumers –

• Non-organic VS organic milk
• Confined VS free range dairy cattle
• Milk mixed from multiple dairy herds VS milk from a single herd
• Homogenised VS non-homogenised
• Milk sourced from more traditional breeds of cow

Discussions around traditional breeds, milk from single herds, and a free-range grass grazing for herds feature on pro-‘raw’ milk websites. Such discussions are also used as pro-‘raw’ milk consumption arguments. Perhaps the ‘raw’ milk advocates have a point. Many people in developed countries, as they seek healthier, more ‘natural’ food for themselves and their families, lean towards food sourced from more traditional style farms and processors. The rise in the organic food movement is a perfect example. Is this such a bad thing?

Perhaps modern dairy-farming and milk processing practises have altered the taste and some properties of milk. Is it such a good idea to mix milk from multiple herds? Should dairy cattle be allowed to be free range? Is homogenisation a good idea and does it alter proteins in milk? Is it a good idea to fortify milk with vitamins? Perhaps ‘raw’ milk that is organic, free range and not homogenised is more ‘natural’ and resembles milk as it exits a cow’s udder than that which is pasteurised, homogenised, fortified and source from grain fed confined cows? Yes, I think it would. And this I can see is a big incentive for some people to consume ‘raw’ milk.

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More on Experts & the ‘Raw’ Milk Debate

While researching the debate / controversy surrounding the consumption of ‘raw’ milk I have come across a number of websites and ‘raw’ milk advocacy organisations that list scientists as members of staff, contributors or active campaigners. I find this rather interesting.

Does this lend these pro-‘raw’ milk groups air of legitimacy? Does it indicate to readers (members of the lay public, farmers and perhaps other scientists) that there is backing by those in the scientific community for some of the claims made about health benefits or the safety of ‘raw’ milk? Does it lend credibility to their side of the argument?

Scientists and medical doctors may not necessarily be experts in food-borne illness, infectious disease and bacteriology, or dairy farming and milk processing. Are these individuals working outside of their area of ‘expertise’, training and knowledge? Are they qualified to comment on such topics as the risks involved in consuming ‘raw’ milk, bacterial pathogens in ‘raw’ milk, the safety of ‘raw’ milk, health claims and modern dairy farming and milk processing practises?

The Raw Milk Institute, is an interesting case of an organisation that has a clear pro-‘raw’ milk message “uses and promotes science-based food safety principles to help create a secure foundation for the growing raw-milk movement.” The Institute has developed standards for raw milk production. Although there appears to be a lot of weight given to scientific qualification of its staff and the scientific research it conducts, there is still some pro-‘raw’ milk rhetoric throughout the content on the website, e.g. ” big believer in raw milk and used raw milk to fuel herself in the world’s hardest race.” Staff and members of the advisory council include a veterinary epidemiologist, alternative health practitioners, ‘raw’ milk farmers, artisan food producers, medical doctors, a biologist, ‘raw’ milk consumers and ‘raw’ milk advocates. Although the Institute “encourages, promotes and undertakes research, using approved scientific methods,” I am a little skeptical as the organisation is clearly biased towards ‘raw’ milk and clearly have an advocacy role to play. The fact that the Institute has developed standards by which dairy supplying consumers with ‘raw’ milk can work by is perhaps a good first step for regulation or ‘raw’ milk producers.

Maybe some medical doctors and scientists are suitably qualified to common on the issues around ‘raw’ milk. Perhaps others are simply advocates that use their qualifications to lend credence to the pro-‘raw’ milk argument.

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Consumer Rights

Following on from my post – Social Components to the ‘Raw’ Milk Debate, I am wondering if ‘consumer rights’ plays a large role in the active protest movements of the ‘raw’ milk advocates? And should the government take more notice of individual’s rights along with personal opinions and wishes.

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‘Raw’ Milk, Probiotics and Lactose Intolerance

I am intrigued by the health claims that are made about ‘raw’ milk. Claims including –

• It contains probiotic bacteria
• It cures asthma
• It cures allergies
• It lactose intolerance

But what is the truth in these claims and is there any scientific evidence to back up these claims. Over the last few months of reading and blogging about ‘raw’ milk, I (with my scientific and critical thinking) have wondered whether there are research studies that back up or refute these claims, and perhaps controversially would a study comprehensively ‘proving’ or ‘disproving’ this claims close the debate over ‘raw’ milk. I acknowledge that the debate / controversy is a lot more complex, but perhaps scientific evidence, improved risk communication and a changed communication strategy (moving away from the deficit (‘you know nothing so we have to tell you everything’) way of communicating) may solve this debate /controversy.

But back to the health claims made by ‘raw’ milk advocates (the pro-‘raw’ milk side) and a critical examination and analysis of research study results concerning these claims. Below I have quoted from the Hot Topics page of the Real Raw Milk Facts website (accessed 18th August 2014), a website run by veterinarians, food safety academics and ‘raw’ milk consumers with support from a legal firm that represents victims of food-borne illness.

On probiotics and bacteria in ‘raw’ milk –  “In consumer surveys, raw milk drinkers often cite “good bacteria” or “probiotics” as the most important reason for choosing to drink raw milk. The international definition of probiotics is “live microorganisms which when administered in adequate amounts confer a health benefit on the host. While raw milk is widely promoted by producers as a probiotic, there are no studies showing that it meets the definition of a probiotic. In fact, raw milk produced using good hygiene should have hardly any bacteria in it at all. Milk from a healthy animal (or human) is sterile when it leaves the mammary gland. As the milk moves through the skin/teat canal, it may pick up small numbers of bacteria from the skin (not enough to be a probiotic). Once the milk is outside the animal, any other bacteria or viruses that get into the milk would have to come from the environment (faeces, flies, dust, equipment). Bacteria from the environment, especially feces and flies, are not likely to be probiotic, and may even be pathogenic.”

On lactose intolerance and ‘raw’ milk – “A number of consumers have also said that they choose raw milk because they believe it relieves or eliminates lactose intolerance. To study this claim, Stanford University scientists conducted a study to compare lactose intolerance symptoms in people given raw milk with those given pasteurized milk (the study was “blinded” so the participants did not know which one they were drinking). The authors concluded “Claims that raw milk is well-tolerated by lactose intolerant individuals, as examined in this study, are unsupported and misleading for individuals with true lactose malabsorption.” A 2010 study conducted by Stanford University researchers (http://www.marlerclark.com/pdfs/RawMilkPoster14Oct10-1.pdf) explored the effect of raw milk on lactose intolerance symptoms. They concluded, “These results, collected under standardized and controlled conditions, do not support the widespread anecdotal claims by proponents that raw milk has benefits over pasteurized milk regarding the symptoms of lactose intolerance.”

Asthma and other allergic conditions – “Among the various health claims about raw milk, asthma and other allergic conditions are the only diseases that have been studied by scientists. Researchers in Europe suggested that raw milk consumption by children at an early age may have a protective effect against asthma and eczema (http://www.ncbi.nlm.nih.gov/pubmed/17456213). However, it is not clear if the protection against allergic conditions was due to raw milk consumption, living in a farm environment, or both. The authors still warn that the risk of pathogens in raw milk outweigh its benefits as a food source to prevent allergies. Before trying raw milk in a child with allergies or other conditions, parents should proceed with caution and talk to their pediatrician or health care provider about the possible risks of serious bacterial infection such as E. coli O157:H7.

I think the above information presents a convincing argument. But what about the testimonial or anecdotal ‘evidence’ presented by ‘raw’ milk advocates in support of their claims about the health benefits of ‘raw’ milk? Can this even be considered ‘evidence?’ But that said, the experience of individuals can’t be wholly discounted. Or maybe there is even psychological or psychosomatic elements at play in individuals claiming to be ‘cured’ or free of the symptoms of allergies, asthma or lactose intolerance. Do they ‘believe’ they have been cured?

Real Raw Milk Facts also discusses testimonials and anecdotes – “Testimonials and anecdotal information can still be helpful in generating “hypotheses” about possible benefits. But until the research is conducted, testimonials are theoretical.” The following is recommended – ‘It is a good idea to be skeptical if something sounds too good to be true (remember, raw milk is still simply milk from an animal).”

Perhaps everyone involved in the debate needs a little skepticism? Perhaps more research is required to produce substantial evidence that ‘raw’ milk does not cure or reduce these ailments or harbour probiotic bacteria.

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Debunking the Myths Around ‘Raw’ Milk

Listed below is some interesting information from the U.S Food and Drug Administration webpage called – Raw Milk & Pasteurization: Debunking Milk Myths, a not so subtle  ‘jab’ at the ‘raw’ milk advocates and their claims regarding pasteurisation and ‘raw’ milk. The webpage states –

“While pasteurization has helped provide safe, nutrient-rich milk and cheese for over 120 years, some people continue to believe that pasteurization harms milk and that raw milk is a safe healthier alternative.

Here are some common myths and proven facts about milk and pasteurization:

• Pasteurizing milk DOES NOT cause lactose intolerance and allergic reactions. Both raw milk and pasteurized milk can cause allergic reactions in people sensitive to milk proteins.
• Raw milk DOES NOT kill dangerous pathogens by itself.
• Pasteurization DOES NOT reduce milk’s nutritional value.
• Pasteurization DOES NOT mean that it is safe to leave milk out of the refrigerator for extended time, particularly after it has been opened.
• Pasteurization DOES kill harmful bacteria.
• Pasteurization DOES save lives.”

I am hoping to examine the evidence put forward from both sides in this debate, and I would like to explore some of the scientific evidence refuting (and perhaps in support) of these claims.

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An ‘Expert,’ Information & Opinion

Following on from my post – Experts & Expertise – continued I wanted to post on an article I read early in my research on the ‘raw’ milk debate / controversy. The article, Those Pathogens, What You Should Know was written by Ted Beals, MD and is on the pro-‘raw’ milk advocacy website http://www.realmilk.com. It is an interesting example of information presented by individuals that could be perceived to be experts interlaced with personal and biased opinion. The article discusses food-borne pathogenic bacteria (with some poorly written and erroneous scientific information. e.g. the statement ‘Campylobacter jejuni grows only inside living animal cells’ is incorrect. C. jejuni can multiply outside living cells – I studied Campylobacter for my Masters research, but I am not proclaiming to be an expert or know everything there is to know about Campylobacter), an analysis of risk (inducting conducting his own calculations and analysis of statistics) and commentary on the perpetration of myths and failings of government agencies in relation to bacterial and epidemiological knowledge and analysis. A list of references is included at the end of the article, however there is no in text referencing so a reader does not know the sources of the information quoted. The most interesting part of the article is the biography of the author –

“Ted Beals, MS, MD, is a physician and board certified pathologist, who served on the faculty of University of Michigan Medical School. He is now retired after 31 years of clinical and administrative service in the Veterans Health Administration. A pathologist with personal interest in dairy testing and safety of milk, he has been presenting testimony on dairy safety in North America for the last several years. Ted and his wife Peggy, as cow shareholders, have enhanced their diet with over 600 gallons of their own fresh unprocessed milk.”

Based on the information in the biography, the author does not appear to be either an expert in epidemiology, statistics or bacteriology. The author however, has a personal interest in dairy testing and safety, consumes ‘raw’ milk and has testified on food safety.

The article, although presenting scientific information, also contains personal opinion, bias and a clear pr0-‘raw’ milk message. Is this article, written by someone who could be perceived as an ‘expert’ or someone qualified to comment on scientific information (due to being a medical doctor), presented as ‘scientific’ justification for discrediting government information about consuming ‘raw’ milk, risks involved and encouragement to consume ‘raw’ milk? Are the medical qualifications of the author being used to add gravitas and plausibility to pro-‘raw’ milk arguments?

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Experts & Expertise – continued

Following on from my post Experts, Expertise and the ‘Raw’ Milk Debate, I wish to discuss in depth experts and expertise in relation to the ‘raw’ milk. In class we learnt that ‘experts’ are individuals widely recognised as being knowledgable on a particular topic. Expertise is the knowledge held by ‘experts’. But as we discussed in class, expertise ideally is not that of a single ‘expert’ but rather that of a collective – many different people with different experiences and knowledge working together.

Two things struck me about our in class discussion these were –

• Expert (and expertise) is conferred (either by others or self-appointed)
• There is a relationship between knowledge, truth, beliefs and their relevance to each other

And these two points are very relevant to controversial topics. When you look at experts in this way it seems to instantly call into question the nature of expertise and ‘knowing lots about a particular subject matter.’ If someone is a self-appointed ‘expert’ does that then leave room for personal opinion and perspectives to come into play?  And do ‘experts’ have their own agendas they are pushing? How does truth (or non-truths) and beliefs then influence how ‘experts’ communicate about these controversial issues?

I find it interesting that within the context of a topic that has a certain level of controversy or debate around it, there seems to be heightened levels of skepticism and conspiracy theorist thinking. Why is that? Is it because of doubt over the evidence presented by these so called ‘experts?’ Is is due to doubt over their expertise? Or is adherence with and the following of a certain ideology that encourages mistrust and conspiracy theories?

I have many questions……. but I’m not sure I can answer them all

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‘Adding Fuel to the Controversy Fire’

While reading and researching material for this blogging project on the ‘raw’ milk debate / controversy I have been trying to formulate some thoughts on why this controversy has arisen. I have yet to come up with a succinct answer/s, but I have a few questions that may be influencing and ‘adding fuel to the controversy fire’ –

• The language (in the style of the deficit model of communication – assuming the public knows nothing and organisations inform the public in authoritative ways and don’t take into account the experiences and knowledge of individuals) in which public health agencies, government departments and scientists state the dangers of consuming ‘raw’ milk, risks involved in consuming ‘raw’ milk and food-borne illness associated with ‘raw’ milk
• Do members of the public just want to know ‘what is the risk of getting sick if I drink some raw milk?’ and do public health agencies etc clearly present this type of information?
• Does this language create a negative reaction in members of the public wanting to know more about ‘raw’ milk and spurs them to look elsewhere (other internet sources) for information? And stumble upon webpages and information on the pro-‘raw’ milk side of the debate?
• Do the numerous webpages and blogs of pro-‘raw’ milk supporters, advocates, lobby groups, charities and organisations capture more readers (due to their high numbers, prominence in google searches, use of everyday language etc)?
• Do the social issues (government control, conspiracy theories, support for raw, wholesome and natural foods, and support for local farmers) ‘hook’ readers in?
• Does the desire in ‘raw’ milk consumers to live healthier lives and help alleviate allergy and asthma symptoms override potential risks of contracting a food-borne infection?

I will continue mulling over these questions and perhaps I can use this for the essay assignment I have to write on my chosen controversy.

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Links to Public Health & Government Information on ‘Raw’ Milk

A selection of hyperlinks to webpages, fact sheets and documents on ‘raw’ milk produced by public health agencies, food safety agencies and government departments from Australia, the USA and the UK –

• Queensland Health – Food Safety Fact Sheet 52 – Raw Milk – a fact sheet
• Biosecurity SA (South Australia): Food Safety – Information in response to questions about raw cow’s milk – a webpage
• Centers for Disease Control (USA) – Food Safety & Raw Milk
• Foodsafety.gov – Milk, Cheese, and Dairy Products – Myths About Raw Milk
• U.S. Food and Drug Administration – The Dangers of Raw Milk: Unpasteurized Milk Can Pose a Serious Health Risk
• Food Standards Agency (UK) – Raw drinking milk and raw cream control requirements in the different countries of the UK

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