E. coli, grass, and pasteurization

Nina Plank, the author of the NY Times article I commented on in this post, stopped by to comment. Rather than just having this lost in the comments to a week-old post, I wanted to take a moment and quickly address two of her points (with potentially a follow-up post next week when I have a bit more free time).

First, to Nina, thanks for stopping by. I'll just say that I very much disagree with your stance on raw milk and dairy. Indeed, contamination can also happen after pasteurization and nothing replaces vigilance, but having seemingly healthy cows is no guarantee of healthy milk. Remember that many organisms that are harmful to us cause no disease in cattle.

Apropos of this, just since I arrived back at my computer from teaching I found these announcements in my email inbox:

E. coli cases linked to unpasteurized milk

Two children have been sickened by E. coli bacteria in a case associated with unpasteurized milk, the [Washington] state Health Department said Thursday.

Testing confirmed both cases were caused by the same strain of the bacteria, E.coli O157:H7 - also the strain at issue in the recent spinach recall.

The children were identified only as a King County boy and a Snohomish County girl. The boy remains hospitalized in Seattle.

"Consuming raw milk can be risky," especially for children, the elderly and people with other health problems, said Janet Anderberg, a specialist with the agency's Food Safety Program.


State revokes dairy farmer's license

The state has revoked the milk-producing license of a western Ohio dairy farmer whose farm sold raw milk, the agriculture department said.

Farmers in Ohio cannot sell raw milk for human consumption, although they can drink the unpasteurized milk from their own cows.

Carol Schmitmeyer's farm in Darke County also did not properly label its product and processed milk without a license to do so, the Ohio Department of Agriculture said.

Agriculture officials said they began investigating after a 63-year-old man and a 4-year-old boy who drank raw milk from the farm became ill.


Raw milk still quarantined

State officials yesterday continued their quarantine of raw, unpasteurized milk products produced by Organic Pastures of Fresno because four children, including two 8-year-olds in San Diego County, became ill after consuming them.

The quarantine began Sept. 21 after stool samples from three of the four youngsters revealed 0157:H7, a type of E. coli bacteria. People affected by this bacteria can suffer severe diarrhea and other potentially fatal complications.

I'll note that it's not yet been 100% determined in this latter case that the milk was the source of the E. coli, but if it is, both of these outbreaks were completely preventable with pasteurization. If you're so worried about losing the vitamin C from pasteurization, eat some fruit. If you want beneficial bacteria, eat some yogurt. There's simply no justification for drinking something as potentially harmful as raw milk.


Being a skeptical sort, in every case I look for objective evidence to back up my choices - and my advice.

Yet you seemingly ignored studies which go against your statement that you "...[are] confident that reducing grain-feeding would reduce O157." As I pointed out, results have been mixed when that was implemented, and O157 shows up even in mostly grass-fed cattle. I simply think it's a lot more complicated than you make it out to be, as I noted in the post.

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Re the mixed studies on the origins of O157, I don't ignore them. But I think the evidence that O157 - a new strain - prefers and thrives in a highly acidic hindgut is strong enough, that, to repeat, my view is that 'reducing grain-feeding would reduce O157' - and I think it's worth doing. That's all.

On raw milk, reasonable people differ! Happily the main diseases transmitted in the old, unhygenic days of raw milk - brucellosis and TB - are all but eliminated with better cow health and widespread testing. Furthermore, raw milk is sterile when it leaves the cow. Thus all contamination is, of course, post-harvest. A clean food chain is what we're after, here. Fresh raw milk also contains healthy bacteria that crowd out unhealthy ones. (If milk is left to stand at room temperature and contaminated with pathogens, they spread faster in pasteurized milk than in raw.)

I only drink raw milk I'm confident of, and that is typically from farmers who drink it themselves. I know many dairy farmers - including conventional farmers who sell milk in bulk to the large dairy processors - who do.

There is good information on raw milk at www.WestonAPrice.org and www.raw-milk-facts.com for those who are interested.

We all await with interest the food safety detective trails tracing the E coli illnesses, in the spinach cases, and in the possible milk cases you post here.

Cheers, Nina Planck


I'm in full agreement with you on this - I'm following both outbreak stories and there are a lot of people jumping to conclusions on it based upon particular predispositions. I'm going to write a post about this, although I've already talked about it on my radio show last night. I'll provide a link when I get around to it this weekend.

Nina, I'm rather curious how you can simultaneously claim that raw milk is sterile when it leaves the cow, and that raw milk automatically contains healthy bacteria. Where did that healthy bacteria come from, if not from post-harvest contamination? And how do you know that only healthy bacteria are getting into the milk? Doesn't that gap of knowledge concern you if you're going to drink it while pregnant?

Organic Pastures in Fresno, CA, to their credit, has posted their bacterial counts on their website, however, they recently announced that they couldn't guarantee that their milk arrives non-soured, nor could they afford to replace containers of milk that have arrived sour anymore. That doesn't sound like very good quality control, and we may find that children are sick because of it.

There's an awesome apple juice that comes from Sebastopol, CA, just north of my home town Petaluma, and I can get it in the stores here in Davis. You have to shake it before drinking, and it tastes great. However, even in light of the Odwalla E. coli outbreak and others, the guy who makes this apple juice grumbles about the Davis Food Co-op and its "regulations" forcing him to flash-pasteurize the juice if he wants to sell it there. He would rather sell it raw.

It's an accident waiting to happen. If its bottled, sotred, and shipped, it should be sterilized. You lose a lot of nutrients when you get sick, you know.

Gee, with all this danger in drinking raw milk, you'd think someone would invent a process to make it safer and kill any bacteria that might be contaminating it...

raw milk is sterile when it leaves the cow.

Fresh raw milk also contains healthy bacteria that crowd out unhealthy ones.

Um, it kinda looks like you just contradicted yourself here. Unless you think that something can contain "healthy bacteria" and still be "sterile", in which case I don't think you know what "sterile" means.

I'm sure that raw milk does contain healthy bacteria - living, metabolizing, propagating. The bacteria's health is not my primary concern, though, I must admit. And drinking raw milk when the farmer drinks it just guarantees that he'll get sick the same day I do; it may protect against deliberate corner-cutting, but not against incompetence or plain old bad luck.

I admit to ignorance concerning the pH of cow guts and the effects thereof (although didn't Tara already address this very point?), but aren't there simpler ways to change cow gut pH if that is indeed a problem? Antacids for cows would seem to be a simpler solution than overhauling the whole dairy industry. (And beef too, I guess. You wouldn't want beef cattle acting as a reservoir, even if they weren't a direct source of human infection.)

Oh, one more thing: if a possible transmission route is the use of cow manure to fertilize spinach fields, would it be possible to pasteurize the *manure* (or apply some other bactericidal treatment)? That wouldn't necessarily stop the spread from cow to cow within the same herd, but it seems like it might reduce the spread on a geographic scale.


I'm currently in the learning procecss about the gut pH issue and the connection to O157:H7. It seems from the research that was pulled up, as Tara has mentioned, there isn't the kind of data to make firm conclusions. The corn-to-hay transition was short term, for instance. I know many cattle farmers make the effort to prevent their cows from contaminating water sources with their manure - that could certainly intervene in this case.

I also remember reading that the irrigation water came from underground, not the streams. It would be easy to test for fecal contamination of groundwater - coliform tests are routine in municipal water monitoring.

Manure does have an equivalent of pasteurization - composting. Although organic farms are dependent upon manure as fertilizer, organic standards require that manure must be composted if it is to be applied within a certain time before harvest. Depending on the crop, it can be 30 days, 60 days, or 90 days before, I think for spinach it must be 90 days because it is right on the ground. (Corn cobs, for example, never touch the ground.

HOWEVER - the compost must get above a certain temperature for a certain period of time to kill off the O157:H7 bacteria, and longer for other kinds. There is no requirement to ensure that this happens, as Sandra Porter pointed out on her blog. Manure as fertilizer is still suspect. Again, its interesting to see people's predispositions at play in this issue.

Nina, the cattle aren't spinach comment is still out there. If manure is used for fertilizer, switching food sources for only the period of time before slaughter won't keep O157 out of the food chain. As O157 can be detected in herds regardless of their primary food source, this still doesn't eliminate the possiblity of contamination of vegetables by manure.

If you want to go looking for a clean dairy, feel free. Be sure to inspect every udder for flecks of manure or skin rashes. Make sure the udders are scrubbed before milking, too. Don't forget to check the milk holding tanks, too. Point is, dairies are still dirty places.

Me? I'll take my milk skim and pasteurized. Thanks.

One other thing to keep in mind about raw milk: it can also contain Staphylococcus and Streptococcus.

Including my pathogen of interest, group B strep, which is a leading cause of neonatal mortality. Really a bad idea to drink raw milk, but especially during pregnancy.

The thing is, milk is *theoretically* sterile, but some bacteria can grow in the mammary glands and not cause inflammation. Other infections may not be diagnosed until they're producing rashes or big lumps, etc. There are bacteria in all raw milk; that's why it's not required to be "sterile," but rather to maintain its colony counts below a certain threshold.

Point is, dairies are still dirty places.

Definitely. As I've mentioned, many of the people I've worked with have raised their cows on grass, given them space to graze, etc. My previous landlord had beef cattle, and he'd move them twice a year to the pasture behind my house to graze. You'd see them occasionally with their side covered with shit from brushing up against each other or what not. And even if the udders are treated with an antiseptic prior to milking, that's no guarantee of 100% cleanliness. (Ask anyone trying to do even *human* studies of mastitis pathogens; external contamination is still a worry even if the area is wiped with alcohol prior to collection).

Again, it's just not as simple or straightforward as Ms. Planck makes it out to be.

I used to raise sheep when I was younger, and their hindquarters were simply covered with feces. I've seen plenty of cows with feces on them, and I wonder how someone coudl claim that the cows are all spic and span. This isn't feed-lot ranching, I'm talking about the REAL grass-fed cows in Sonoma County, CA.

I didn't know about the non-inflammatory bacteria in the mammaries, but it makes a great deal of sense.

A professor of mine told me that there is an urban-rural divide, where people from the cities tend to view agricultural issues that they have no personal experience with in black-and-white terms. Rural folks who have seen (if not worked with) those issues view it in a more practical sense. I'm not sure whether that is true in Nina's case, since I don't know much about her save the Op-Ed and comments here, but it does seem to be a sociological phenomenon.

Just a couple of comments

1.) California does have a mastitis test for diary, therefore milking animals with infected mammaries should be screened out prior to milking. Therefore, in theory the milk in the udder should be sterile. What should be done is stripping the teats after washing to ensure that no skin bacteria is in the milk.

2.) There is no justification for commercial milking to not pasteurize, but on the homestead there is. One reason one does not pasteurize is control of the temperature, if you exceed it, you are looking at cheese. The goat is probably the cleanest dairy animal, and can with some breeds produce milk equal in taste to cow's. The issue with goat's milk is its digestibility compared to cow's, and this can be potentially be degraded with pasteurization.

3.) It appears that folks are conflating commercial, organic, and homestead farming. Only homestead farming with the emphasis on intensive work, can one be somewhat assured that a raw dairy product is safe from pathogens.


This is a terrific discussion. From the perspective of emergency medicine and wilderness medicine, where I often have the opportunity to care for persons with infectious diarrhea, one observation is clear: namely, that while it is sometimes possible to track the disinfection path of commercially processed foods, it is very difficult to track the disinfection path of non-processed foods, because no one is responsible for maintaining this information. Diarrhea and its complications are debilitating and lead to very serious outcomes for victims. Furthermore, where is the risk versus reward evaluation? For instance, if one accepts the fact that non-disinfected stream water in certain watersheds carries a higher number of coliform bacteria than does disinfected water, does the nutritive value or taste of the nondisinfected water justify the risk of contracting infectious diarrhea? The value of epidemiology is to identify patterns and quantify risk. Then, it is up to health officials to make decisions about what is in the best interest for populations, while informed individuals can make decisions about what is best for themselves and the persons for whom they are responsible. In the wilderness, food and water disinfection are huge issues, because nausea, vomiting, diarrhea, weakness, and fever are just the tip of the iceberg if they predispose the victim to problems like altitude sickness, hypothermia, and generalized exhaustion.

Hi Paul: As a backpacker, I don't see it as the responsibility of health care folk to address presence of pathogens in drinking water under a wilderness situation. The backpacker/camper should be well informed about such issues like guardia or coliforms, and as to what precautions are necessary--boiling water, periodite treatment, or water filter. It is bad enough with the effects of non-native trout stocking throughout the Sierras, and permitting of cattle grazing in the Paradise Wilderness, to have a true wilderness experience.


"Then, it is up to health officials to make decisions about what is in the best interest for populations, while informed individuals can make decisions about what is best for themselves and the persons for whom they are responsible."

Belay that last message--need more coffee.

Seems to me a common link of contaminated water is the most likely culprit in the spinach/raw milk debacle. Late summer is when water tables drop to the lower end, and ground filtration can't keep up with the demand for water. Thus there may be seasonal variances in the coliform counts of well water. Water testing is usually not performed on a daily basis, statistics may be formulated from only the most acceptable results, and if you carefully read your town's water report, the coliform count is generally listed as a less than rather than none present.
Spinach is hopefully washed before packaging, and dairy equipment is definitely washed between cows and after emptying of milk storage tanks. The water used might be from a well that is not checked for coliforms. Nothing in this world is foolproof, and living means taking some chances. No farmer wants to make people sick, no one in the food preparation business wants to make people sick, but people like Typhoid Mary happen anyway.
The meat packing plants I have seen go to extreme lengths to ensure their ground beef is not contaminated. All of the vats, grinding surfaces, and transport devices are made of stainless steel. Could that be why ground beef is now pricier than a roast?