Alice Evans: Brucellosis, or Why We Pasteurize Milk

It’s easy to forget how much illness and death was caused by our food and drink just one hundred years ago. Our modern food systems, backed by sound research and decent regulation, have elevated food safety to the point where outbreaks of illness are big news. If you get sick from a burger, or a nice tall glass of milk, it’s no longer a mystery what happened. Instead we ask why, and “who screwed up?”

In the early 20th century though, many food-borne illnesses were still a mystery, and microbiology was a scientific endeavor that was just getting started. Alice Catherine Evans was an unlikely figure to make a dent in this world at the time, but through her research at the United States Department of Agriculture’s (USDA), and later at the Hygienic Laboratory (now the National Institute of Health) she had a huge impact on the field of bacteriology, the dairy industry, and consumer safety.

Childhood and Education

In her memoirs, Alice describes her childhood and continuing education as a straight path with limited options:

Until my academic education was completed I seemed never to have an opportunity to make a choice in matters concerning my future. I always stepped into the only suitable opening I could see on my horizon.

Growing up on a farm in rural Pennsylvania, her primary education took place in the local one-room schoolhouse with “good teachers most of the time”. With no high school available in her district, she traveled to a nearby town for her secondary eduction.

Without the financial means to attend college, she pursued the only professional career available to women at the time: teaching. She taught grades 1–4 for four years, but despite finding the children interesting, she quickly grew bored with teaching the same curriculum over and over again. “I was glad when I found a way to escape”, she said of that time.

Her escape was facilitated by another opportunity that presented itself: the College of Agriculture at Cornell University started offering a tuition-free two-year course for rural teachers intended to help them foster a love of nature in their students. Using savings from her time spent teaching, she attended this Nature Study course, and studied botany, zoology, entomology, ornithology, geology, and meteorology. By the time she was done with her studies, she was hooked:

I was no longer interested in obtaining the certificate to which I was eligible. My interest in science had been whetted by the basic courses I had taken, and I wanted to continue the study of science – any branch of biologic science would satisfy me.

Luckily, at this time the college was accepting out-of-state students, tuition-free, to its regular courses. With the help of a scholarship, Evans was able to complete her B.S. in Agriculture in another two years. Being generally uninterested in the study of applied agriculture, she chose to specialize in the only pure science available to her: bacteriology.

Finally, on the recommendation of a professor at Cornell, Evans applied for and won a scholarship studying bacteriology at the University of Wisconsin, where she completed her Masters degree. Afterwards, although presented with an opportunity to obtain a Ph.D. in chemistry, she decided to leave behind the financial and physical strains of college and accepted a research position with the USDA.

Early USDA Career

At this time, the USDA was expanding its research team, but lab space was limited. The USDA was providing funding for researchers who would work in state-funded labs until space in Washington D.C. was ready.

The hiring decisions for these positions were made by the professors running the investigations, so – under this unique structure – Evans was hired in a University of Wisconsin lab as a bacteriologist representing the Dairy Division of the USDA Bureau of Animal Industry. The lab was investigating how to improve the flavor of Cheddar cheese.

Portrait of Alice Evans in a laboratory, observing a test tube
Alice Evans in 1915. Source: Wikimedia Commons

On July 1, 1913 researchers were required to move into the newly completed laboratory in Washington. On her journey an acquaintance in Chicago – who had just returned from the USDA – related that the Dairy Division “did not want any women scientists”:

According to hearsay, when the bad news broke at a meeting of B. A. I. officials that a woman scientist would be coming to join their staff, they were filled with consternation. In the words of a stenographer who was present, they almost fell off their chairs.

Apparently the Bureau’s officials had never considered the possibility that the local professors in charge of hiring USDA investigators for their labs would want a woman on their research teams.

Regardless, as she settled into the new lab, she found that her immediate superiors didn’t share the Bureau’s view of women scientists, and it was a good place to work. The Dairy Division had many investigations already under way when she arrived, including studying the effects of pasteurization on milk, researching manufacturing methods for butter and cheese, and searching for sources of bacterial infection in dairy products.

Her first assignment was to collaborate with a chemist to find methods for identifying bacteria. As this research did not fill her time, she was given a problem to investigate on her own: she was to study the bacteria that occur in fresh milk. This task led to one of her most important discoveries: the link between a cattle-borne bacteria (later named Brucella abortus), and a feverish illness in humans.

Brucella and Undulant Fever

Contrary to many summations of Evans’ work, she did not discover the Brucella abortus bacteria itself. Brucella abortus was already identified (though named Bacillus abortus at the time) as the cause for spontaneous contagious abortions amongst cattle, and was known to exist in the udder and milk of apparently healthy cows. It had even been suggested that this bacteria could infect humans. And so, she says:

The idea of drinking milk contaminated with bacteria capable of causing disease in animals was distasteful to me.

This led her to focus on Brucella abortus and to investigate whether it was related to any bacteria known to cause human disease.

A consult with a Bureau pathologist provided her first clue: she discovered that goats who appear healthy can infect humans with what was then called undulant fever or Malta fever. This set her off to investigate the relationship between Brucella and the bacteria that cause undulant fever.

A microscopic view of Brucella melitensis‘s coccobacillus shape. Source: Wikipedia

There was a pretty good reason that nobody had ever guessed that the two bacteria were related: the bacteria that cause undulant fever had been described as spherical in shape, and were thus lumped into the Micrococcus genus, whereas Brucella abortus was considered to be rod-shaped, and had been placed in the Bacillus genus.

Evans discovered that the shapes of both strains are actually similar: rod-shaped, but divided into varying lengths, with some segments so short as to appear spherical. Depending on growth conditions some cultures could present as mostly spherical.

The physical similarities between the two bacteria prompted Evans to investigate further. The laboratory tests available at the time for differentiating bacterial strains found that they behaved alike. Tests on pregnant guinea pigs were also performed, with both strains causing abortions along the same timeline.

These findings were presented at a meeting of the Society of American Bacteriologists in December of 1917. In the subsequent paper, Evans commented on how, given the similarities between the two bacterial strains, and the reported infection rate in cow’s milk, “it would seem remarkable that we do not have a disease resembling Malta fever in this country”. Further:

Are we sure that cases of glandular disease, or cases of abortion, or possibly diseases of the respiratory tract may not sometimes occur among human subjects in this country as a result of drinking raw cow’s milk?

The paper was met with skepticism, but Evans’ claims would eventually be confirmed over the next decade, and both strains of bacteria would be placed under the Brucella genus, with brucellosis becoming the new name for the fevers and other symptoms caused by Brucella bacteria.

Effects of Her Research on the Pasteurization of Milk

Evans’ research eventually helped convince the dairy industry that pasteurization of all milk was necessary, but not without a lengthy struggle. One issue was the belief that a healthy-looking cow would always produce healthy, low-bacteria milk. Evans’ research had shown that this is not true, but science can be slow and uncomfortable evidence can be ignored, especially when pasteurization equipment is so expensive.

The dairy industry developed a grading and certification system instead. Everything below Grade A would be pasteurized. Grade A was harvested from healthy-looking cows inspected by veterinarians, and handled under the strictest cleanliness conditions. It had very low bacterial counts and Big Dairy thought that was enough.

But it wasn’t enough. Though opposition to pasteurization was already on the decline, an ironic case of brucellosis proved to be a turning point: the child of an officer in the dairy industry came down with the illness. They had only consumed certified Grade A milk, of course. This made the issue plain to see and helped convince the remaining doubters that pasteurization was necessary to ensure the safety of milk and other dairy products.

50 thoughts on “Alice Evans: Brucellosis, or Why We Pasteurize Milk

  1. Most important pasteurization continue as the disease can last for years and the less of that bacteria around the less chance for mutations, more info on the disease here:- https://en.wikipedia.org/wiki/Brucellosis
    This comes up in Food Science as covered in microbiology, I did my post grad 2010 best thing I ever did as had opportunity to assess declining minerals in food and widespread deficiencies which can exacerbate several conditions such as; MS, diabetes, dementia, parkinsons and severity of auto-immune conditions eg Ankylosing Spondylitis.

    Thanks for post, worth getting to grips with bacteriology as some 100 new species appearing or being discovered each week to month – with many mutations since exposures to industrial compounds last 100yrs…
    Cheers

    1. Interesting. The auto-immune stuff is relevant to me, unfortunately. I hadn’t considered it as a kind of herd immunity thing. I sometimes encounter people who are all up in arms against pasteurization, saying that since they know how to handle milk safely (many are dairy farmers) then everyone should be able to. Of course it’s a numbers game, and it’s useless to just say people should be able to do this or that. Society doesn’t work that way. At the end of the day, lots of people will get sick and die when compared to the world before pasteurization.

      Was your grad work about the lack of minerals due to things like pasteurization? Is there a situation of removing necessary nutrients and bacteria and along with the dangerous ones?

      1. Here’s the under graduate course at the University, post grad pretty much same, less onerous if credit from earlier degrees, very easy for me as electronic engineering studies at same campus 30 yrs before and then Ba. Sci confirmation 2008. Few minor course changes since 2010, here in general
        https://scieng.curtin.edu.au/schools/school-of-molecular-and-life-sciences/food-science/
        And the details in respect of units, can ask the uni for their outlines, includes pc1 microbiology lab investigations into pathogens as well as Bifido bacteria types.
        http://handbook.curtin.edu.au/courses/31/319743.html
        My motivation from the 2 years prior to studies in 2010 was informal research into possible dietary influence factors in respect of predisposition to Alzheimers since my mother showed signs from 2005. Of particular interest is the protein binding plaque issue in relation to CSF permeability and osmosis related to non infectious prions. I soon learned we are nowhere near an ideal mineral homeostatic ingestion level of so many nutrients it’s scary. I discovered there are several mineral deficiencies very common on western diet some serious and significant related to many late onset diseases incl MS and diabetes as well as contributory factors to genetic predispositions, many deficienciex involve (at the very least) immune system signalling, neural function, bacterial interactions with immense permutations across the whole spectrum etc The course has no particular specialisation in respect of minerals and since the post grad is effectively part time it left me lots of time to wade through hundreds of peer reviewed journals 2010 with now over a 1000 total to date since 2008 or so…
        Pasteurisation in normal practice does not reduce minerals or their bioavailability in respect of competing absorption via the gut or interaction with the approx 800 species of gut bacteria.
        I make my own supplement formulation which my eldest son also takes with limited availability for casual enquirers and all subject to strict selection criteria.
        The most important for immune function being copper and zinc as they also play roles in immune system signalling, secondary iodine with small amount of selenium with molybdenum and magnesium. Note: Cu a necessary moderator for the neural NMDA receptor ie insufficient Cu accelerates neural dysfunction reducing intelligence, the WHO studies show approx 80% of subjects in USA well below old tabled RDI whilst exposed to high fructose depleting the brain of minerals – this seriously affects frontal/temporal lobe communication paths with the emotional limbic system making most far more pliable to propaganda ie less able to connect education of evidence with (emotionally manipulative) claim. Anecdotal proof they did vote for trump ;-) Though testament to the situation overall no side had any good broad brush intelligent candidates, consider their preselection motivated by increase in power base not consistent with good governance or even ethics for that matter the US seems to operate capitalism as if their populace a crop for exploitation :/
        Also note:- Cu has very high ingestion dynamic range, arguably humans adapted to doses approx 100-200 times higher (for > 3000 yrs) than we get now even on meat diet ie We used to frequently eat out of And store food for long periods in copper bowls till about 300 years ago. Note after that time even minor cuts could result in death due to common bacteria as less Cu means far less anti-bacterial activity. Most in 1st world war died from infections… Homeostatic level for Cu approx 100mcg/Kg body weight/day whilst average dietary intake per day 300mcg, do the math observe how serious the issue is with tendrils spreading far and wide !

        1. For me your mix-up of probable scientific stuff with political conspiracy theories brings your whole posting in an unacceptable esoteric or conspiracy-theorist context, it severely devalues if not invalidates your credibility.

          1. What Martin what line are you taking and where is the substantive evidence for an idea ?
            Criticism from unconnected nicks with no credentials = lose all credibility and nil audit trail :/
            Try again please, are you reading and thinking carefully (copper deficiency marginalisation your NMDA receptors perhaps) – where is there Any political conspiracy issue touched on even tangentially or are you just knee-jerking my very minor satire – notice the wink ;-) ?
            It’s obvious, when you bother to look at the issue even a little that a large facet of that which has developed in terms of food preparation and storage over last 300 years or so arises from a (mostly casual incidental) conjunction of complaceny with widespread lack of education with general public and many scientists arbitrary acceptance of the status quo as it gradually entered usage as if ‘all is right with the world – so be simple and don’t rock the boat’ :-(
            How does that offer any convergence on the essential truths ? One of which is (primarily caucasian) humans (with interbreeding of other races from middle east to Asia) adapted over many 1000’s of years to eating from copper bowls And storing food that degrades releasing food acids thus offering very high copper levels, some of which influence gonads conferring infertility except through those gene lines able to procreate under very high Cu ingestion levels approx 100-200 times, sometimes even higher than your current average (non supplemented) levels…
            Observations of consequences from accepted patterns does not imply conspiracy, though it does offer fodder for a script for a SciFi series of sorts, not confirming I write these (if I did under a pen name) though I do find it an entertaining past time ;-)
            IOW. My intent is to point to verifiable facts which relate to consequences, any tests at humour and satire along the way cannot point to issue of addressing intent about conspiracy. In any case I do not claim to be any sort of authority figure so issue of credibility is moot. If however, you refuse to look into the issue further such as peer reviewed journals I play no part in, then by equal complaceny others have shown you acknowledge acceptance of my experience in such investigation thus via inference accept my credibility :D
            In any case you can confirm my University credentials and Food chemistry distinction too !
            My student number 7602128 at curtin.edu.au prior to that at Western Australian Institute of Technology it was 760212D ask them check, as that’s what the discipline of science progress is predicated upon… ie no arbitrary unconnected facile claims, Provenance essential :-)
            Cheers.

          2. Indeed, well this one of the other strange things as it’s very difficult to get any sort of high levels of copper ingestion from copper cups (even when they have the classic green corrosion) especially as the homeostatic level for humans is around 100mcg per kg of body weight each and every day. It should be noted that it depends where the cups come from as there are other contaminants at play – such as random levels of lead, antimony and arsenic. In particular arsenic is quite common and widespread in India. Interestingly if you want to enter the Arevayda tradition as a neophyte monk then you must first consume water stored in copper vases for a year before allowed entry. The rationale appears to be this is cleansing in some bacteriological/spiritual context and also raises intellectual capacity when finally admitted. Similar to Iraqi tradition of simmering sheep brains with piece of copper overnight before eating as helpful to raise intelligence of children.
            I hope you will note I’m not suggesting any conspiracy, I made a joke and flagged it via an emoticon.
            FWIW.
            The other issue (and not just for copper btw) is genetic predispositions to various types of flawed metabolisms, such as Wilson’s disease for copper bio chemistry which inappropriately accumulates it in various tissues unequally or rather not in line with best health eeffects for the organism as a whole. So the whole issue of any sort of idea of toxicity may be influenced by the tiny percentage of the population suffering genetic metabolism conditions as if projected upon the whole populace. With some 150 enzymes either with copper in their structure or dependency as co-factor then its logical a healthy ingestion level goes towards wider distribution across the whole range of those enzymes ie. There is no imperative or even tacit guarantee all those enzymes share their copper load collaboratively, there is obviously the issue of local and overall organism distribution according to many levels of dynamic equilibria as we eat variety of foods. The body is in no way “designed” to operate optimally and fwiw no deity cared to educate us in that way either !
            In Australia we have the therapeutic goods administration (TGA) as an authority to guide usage which appears to operate on the basis that copper supplementation be divided down from twice the RDI for the whole bottle loosely associated with homeostatic level daile ingestion is divided down by the number of capsules/tablets in the bottle/tub purchased. As if there is the fear some numb nut will swallow the whole bottles content. Consequence is one cant get anywhere near the RDI from one capsule/tablet per day. It’s a waste of money and time unless you take 20 to 30 per day, so I make my own with other components in a formulation for optimum bioavailability…
            As I wrote in response to Martin, it’s obviously not a conspiracy as such, it’s far more likely a set of conditions with lack of education and complacency as the root causal basis for the whole mess of situations and lazy acceptance as if (and as we say in Australia) ‘she will be right mate’ Or “if it ain’t broke don’t fix it” – obviously woefully simplistic anti-intellectualism missing essential detail as if to maintain some facile comfort zone :-(

  2. It’s still not enough. Now it’s the chemicals resulting from pesticides, and GMOs, and the hormones that the industry is using to amp up the milk production, etc that is causing health issues. So now there is a whole new industry of “organic” to try to solve these problems.

    1. And where is the evidence that the above have any negative impact on anyones health? I’m not opposed to the idea, but often people throw around “hormones” and “GMOs” as the the cause of vague ailments without a shred of evidence.

      1. The problem (of so many) is ballistic transport which is messy causing dna damage it can take generations before noticeable and that means in humans as mix of tetragens and mutagens. One clear case is GM sequences from corn with Monsanto gene added to kill the guts of insects attacking corn BUT, humans vs insect guts not that different so bacteria grab those genes and cause increasing human gut problems. See WHO stats increase in gut disease in US population correlated with increase in certain types of GM corn and others too not yet expressed in several gene sets. There are other complications too in terms of gonads for male and female and add to that cheap fructose in US foods from GM corn has DNA snippets since fructose extraction cheapest so very messy not ‘pure’…
        BTW: Fructose depletes the brain of minerals reducing average intelligence as well as tickling the same receptor that cocaine does – and the food companies wonder why their fructose rich drinks and food consumption rises ;-)
        FWIW: Ask local public health to classify typical fast food buns, not bread – its classified as cake :/

      2. I agree @Buriedcode, I think the panic about GMOs is way overdone, but people are still voting with their dollars. And there is more than just a shred of evidence that food chains carry all the way through to us. Cows eat grains that are optimized for efficiency, they are given hormones that optimize production etc etc. A beef farmer told me once that the steers are given the very same hormones they would have had if they were not castrated. Ok, but in the same quantities? And did the beef industry typically raise uncastrated bulls for meat prior to hormone technology? All excellent questions, hmm…

      3. I think that in this case the burden of proof lies on the other side: that there is no negative impact. But of course it is very difficult to convince someone who’s livelihood depends on not understanding it…

        1. In a lot of this discussion I agree that there needs to be more care taken with agri-tech, but I gotta point out that this kind of negative proof is practically impossible. One can do studies to show that a new technology is reasonably safe in controlled situations, but the amount of study needed to produce positive proof that there’s absolutely no danger whatsoever when it’s out in the greater world is so immense that it’s virtually guaranteed to be inaccurate.

          Of course, with some of our technologies that would have meant that no progress was possible and that might have been a good thing. As we stare down the barrel of ocean die-offs and climate change, we may have been atrociously careless and only borrowing against a future where we’ll pay the ultimate price as a society. It’s hard to say. Such a difficult decision, whether to turn back almost entirely from our modern civilization or take on serious existential risk.

  3. Currently working on several analyzers for dairy. The hand held systems will detect pathogenes throughout the supply chain, from cow to retail store. The other systems will identify sick animals and sort them from the herd.

  4. “But it wasn’t enough. Though opposition to pasteurization was already on the decline, an ironic case of brucellosis proved to be a turning point: the child of an officer in the dairy industry came down with the illness. ”

    Human nature never changes. People react when it affects them, or their loved ones.

    1. More likely is that change is forced only through an insurrection by a significant population percentage; or (more commonly) change is implemented when something affects a member of the ruler/manager class. Engineering rationale, and the body of scientific knowledge, seldom effect change.

    2. I grew up on a small farm where we raised beef cattle and we did not castrate our bulls or give them hormones. We were wiped out by brucellosis. In cattle, it causes them to abort; we lost at least 11 calves before the government made us sell the remaining cows of our small herd for dogfood at 11 cents a pound.

  5. There’s a “raw milk” fad these days where people claim all kinds of spurious “damage” caused to the nutrition content of milk by pasteurization.

    Bloody loons. Just like the anti-vax idiots, ignorant people taking risks with the lives of other people.

      1. > “UNskimmed pasteurized milk”

        Pasteurisation and homogenisation usually go together. Full cream homogenised milk is not skimmed, but the cream does not sit on top like nature made it, because it’s also homogenised, i.e. squirted through a very tiny hole at pressure, which breaks up the fat, and stops the cream from separating. I’m not sure what the advantages of homogenisation are (besides not having to shake the bottle before pouring). Anyone have more info about that?

        1. Homogenized milk lasts longer on supermarket shelves, cream goes sour first, so it is mostly a market/storage convenience. There is some evidence to suggest that the butterfat particles cause problems when too small, though. Skipping blithely through into the bloodstream, possibly causing allergic type reactions, and the like. I personally think that it does adversely effect the taste, or maybe it is really the texture, dunno. I worked on a couple dairies in my youth and one of the perks was as much milk as I wanted(raw, out of the tank before pick up). Probably was a good incentive to keep the SCC low. Anyway, my two bits: pasteurized: good, homogenized: practical, but make your own mind up.

          1. Wait, wait… The butterfat particles are absorbed through the intestine, it isn’t “injected” directly in the bloodstream, so I don’t see how the size of the drops can affect to the bloodstream. And don’t forget that the milk coagulates in the stomach, due to the acids present, so those drops “collapse” much before they are absorbed.

            Your problem with the milk is, I suspect, texture AND quantity of butterfat: by default, all the milk has its butterfat removed, and then the specific quantity is added to the “whole”, and “semi” variants. This has the advantage of having the same quantity of butterfat during the whole year (the amount of butterfat per gallon produced by a cow is different in summer than in winter).

        2. “like nature made it” :-) Basically “nature made it” to be consumed immediately and directly from the source. In that case the separation of the cream has not time to occur. But we want to store and transport milk. But I do not see, what should be lost be homogenizing the milk. Skimmed it is not, except you buy skimmed (low fat) milk.

    1. It’s funny, because in France there was a strong battle for raw milk (it was an EU battle because nobody wants the foreign visitors to get sick when visiting France). It ended up with an incredibly complex and paranoid system to avoid bacteria in the raw milk, basically it’s a separate supply chain. I think it works well, as far as I know the only recent bacterial outbreaks in food in France were meats and pasteurized milk (more like a factory contamination than a milk specific issue).

    2. Right? There are cultures which are nearly entirely lactose intolerant because–big surprise–they stop drinking milk after infancy like every other mammal. How can we assume these nutrients are 100% necessary? There’s gotta be another dietary source for anything that might be in there.

      But I could always be wrong. We’ve been cultivating dairy for a long time as a species.

  6. In South Africa in certain areas (even big cities), one can buy unpasteurised milk in supermarkets. You bring your own (sterilised) bottle, and fill it up from the big stainless steel tank. It is said to be tested for exactly these bacteria that cause serious illness in humans. In my two years living in Bloemfontein, myself and some of my friends (including old and young, married and single, children and parents) drank mostly unpasteurised milk, and never got sick once.

    Pasteurisation is good and all, but science can provide another option – testing instead of assuming the milk is infected.

    I guess in some countries, it’s also not possible to buy non-refrigerated eggs?

    1. Refrigeration of eggs is a different beast, if I recall.

      Please correct me if I’m wrong. If memory serves you can either clean the outer layer off the egg, which will then require refrigeration, or leave the outer layer on. Leaving it on was noted to provide a non-permeable layer protecting against bacteria and what have you.

      Thought that was a Europe/USA difference. Although you may want to look all that up if you’re really interested!

    2. This is an immensely complex issue. Early exposure to pathogens can endow immunity of sorts all else being equal and these days immune system compromises due to 1000’s of industrial chemicals messing with the endocrine and immune system as well as increasing mineral deficiencies compromising immune cells capacity to produce peroxides. Add to that vaccinations of the cattle, different strains not causing immediate symptoms, adding copper sulphate to milking cattle’s feed to increase production to shift gut biodome equilibria bifido/pathogens, some of which acting as antibacterial in milk glands etc NB: All bacteria cannibals and share genetic material, huge permutations its a wonder we survive as unit organisms, add to that bacteria can be commensul in the brain for normal function – so much still needs to be researched!
      Also increasing vaccination of chickens against salmonella in some areas so generally in Australia from ‘safe outlets’ non refrigerated eggs just fine, not in Malaysia where I worked in the jungles of Sabah for 3 months where un-refrigerated eggs gave me salmonellosis – antibiotics free fortunately after self-diagnosis – easiest is metallic taste with nausea/fever.
      BTW: This is why UHT is good as its hot enough to kill sport formers; baccillus & clostridium etc etc etc etc More on the way, so be vigilant, education not a static under any circumstances. 10million + species of bacteria so far !

  7. I had a colleague that had some rare illness that was thought to perhaps come from unpasteurised milk. One of the interesting things that came up was the significant differences pasteurisation standards in the US and Europe. A statistical analysis give the differing standards helped point to the possible cause.

  8. If I recall correctly the temperature used for pasteurisation of milk is determined by the temperature required to inactivate the Q Fever pathogen, coxiella burnetii. Some regions do PCR of bulk milk to determine background levels of pathogens in herds, such as Q Fever. Q fever infection in animals can be asymptomatic, making it hard to assume a herd is disease free, and similarly, one cannot assume that the bulk milk from multiple herds, once combined, is disease free.

  9. I worked a dairy farm as a teen, 60 head, milked twice a day. The milk, once cooled in the bulk tank was amazing. Of course a lot of that was the creamy richness, far beyond what regular vitamin D milk has today. I drank at least half a gallon a day, Still have fond memories of raw milk, but it would be a bad thing to see it on grocery shelves.

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