Sunday, June 3, 2018

E. coli strikes again

Five people in the United States have died since March and approximately 200 are sick as a result of an Escherichia coli infection apparently acquired from romaine lettuces grown in the Yuma region of Arizona.  However, the authorities have been unable to pinpoint the source of the contamination.

Though E. coli are found in the gut of man and animals, only certain strains cause serious illness.  These strains have assembled many genes that enable them to attach to the cells lining the intestine and produce very damaging toxins called Shigatoxins.  This is an example of the continuous evolution of bacteria.  Many of these new strains are the result of bacteriophage infection transferring genes between bacteria or possibly by direct transfer between strains.

Various posts responding to news reports of the outbreak have suggested washing the lettuces as a means of preventing illness.  Unfortunately, washing, even in chlorinated water, will not guarantee removal of the bacteria, as they can attach to the lettuce or even localise in the stomata of the leaves.  I obtained the following image from https://www.inverse.com/article/28938-e-coli-detection-lettuce-feces.





You can see bacteria within the stoma; it is clear that they would be very difficult to wash out.

This outbreak was originally thought to be caused by bagged and chopped lettuce, but inmates in a prison in Alaska also became ill after eating whole head lettuce.  In view of these facts, it is unfortunate that consumer advocates are urging the FDA to introduce new rules to speed up investigation of such outbreaks.  It is hard to see how new rules would influence the investigations, given that it has so far been impossible to tie the contamination to a single farm, processor or distributor.

The one fairly sure conclusion is that the lettuces have become contaminated with faeces, since this E. coli is not a natural inhabitant of the environment.

Wednesday, March 28, 2018

On the turps - it's insane.

In New Zealand where I live, we have a phrase "On the turps".  It means "drinking alcohol" usually, but not always, beer.  When you've been on the turps, you may have a hangover if you were serious about it.

I have a thing about ill-informed food and drink advice, some of which is downright dangerous.  Totally unqualified people seem to think that they can hand out advice on diet, so-called "super foods" and other health issues.

The latest whacky outpouring from a minor celebrity suggests that drinking a small quantity of turpentine with sugar will rid you of a cold overnight.  This is a BAD IDEA.

Turpentine is prepared from the resin of pine trees and, I have to say, smells really nice and fresh.  I used it when I was painting in oils to thin the paint.  Another person giving the advice, this time a disbarred doctor,  claims that her IQ "went up like 50 points".  I think she has the sign wrong - it should be -50 points.

There is plenty of scientific evidence to show that turpentine is poisonous, causing irritation to the eyes and central nervous system and severe damage to the kidneys, or, in sufficient quantities, death.

We have been considering natural turpentine here.  Hardware stores sell "mineral turps" which is a turpentine substitute prepared from petroleum.  Consumption of mineral turps may not be fatal, but can result in lung damage and irreversible brain damage.

Of course, this post is not strictly about food safety, but I believe it is important to get this message out there.

I feel so strongly about misleading food and nutrition advice that I am chairing a conference in New Zealand with the theme "In food we trust: confidence built on science and technology".

Monday, March 26, 2018

A useful Sanitation Checklist.

This checklist was sent to me by Meyer Industrial Solutions.  I have provided it for the benefit of readers, without endorsement of the company.

There are a couple of things that I think merit comment:

  • Step 1.  The use of compressed air to move residues may have the effect of spreading them around the processing area.  Better to manually sweep.
  • Step 2.  If the equipment is contaminated with proteinaceous material, I recommend using warm water for the intial rinse.  Hot water may set the protein and make it more difficult to remove.
  • Step 3.  I agree that the use of pressurised water for rinsing tends to spread contamination around.  I once visited a meat processing facility and found meat scraps on the ceiling, put there by pressurised water!

This was created by Meyer Industrial

Friday, March 9, 2018

Raw milk comments cause another minor furore

This time, a senior scientist has kicked over the beehive and created a minor furore.   Professor Nigel French FRS, Director of the New Zealand Food Safety Science and Research Centre, has stated in an interview that he would not drink raw milk, nor give it to his family.

In my opinion, he is correct in stating that even the most careful production of raw milk cannot avoid some contamination by cow faeces, which, of course, contain bacteria and viruses.  Some of these bacteria and viruses can cause serious human disease.  As a microbiologist, I am fully aware of the sensitivity of microbiological testing and can confirm Prof. French's comment that bacteria can still be present, even if the test shows negative.

Scrupulous cleanliness and attention to detail can reduce the chances of faecal contamination of the milk, but cannot eliminate the risk.  Since the beginning of the year, there have been two recalls of raw milk over fears of contamination by Campylobacter, a bacterium that can cause diarrhoea (frequently bloody), abdominal pain, fever, headache, nausea, and/or vomiting.  Occasionally, it can produce more serious symptoms requiring hospitalisation.

Reading the comments on the article, it is clear that the proponents of raw milk consumption will not be swayed by scientific facts, and it is their right to drink raw milk.  However, the New Zealand
Prime Minister's Chief Science Advisor Dr Peter Gluckman concluded: "The claimed health benefits of raw milk compared with pasteurised milk are for the most part not backed by scientific evidence, making the risk-benefit ratio very high for this food product ..."  

I have written about the hazards of drinking raw milk before (see the label Raw Milk) and the latest recalls simply confirm my opinion.  Many of the people commenting on the report are saying that they grew up drinking raw milk without problems.  What they appear not to appreciate is that our lifestyle has changed.  We don't collect our milk daily; children are coddled and protected from exposure to bacteria by the use of antibacterial soaps and cleansers, they don't go out to play in the dirt and often they are not exposed to farm animals.  In my opinion, their immune systems are less robust.  At the very least, children should not be fed raw milk - they have no ability to refuse it.  

The regulations surrounding sale of raw milk have been tightened considerably, including labelling and warnings on bottles.  Raw milk cannot be sold from health food stores and use-by dates must be printed on the packaging.  It is interesting to note that sales of raw milk are not permitted in Australia.

Sunday, January 7, 2018

Wild meat and botulism - update.

As I suggested in the original post, the tests on food and other samples have now shown that the poisoning of the family in New Zealand, apparently caused by Clostridium botulinum, was not caused by botulin toxin. However, no other explanation for the families symptoms is forthcoming. Conspiracy theorists are suggesting the boar had consumed 1080 poison (used for possum control) but there is no evidence for this. Many other toxins could be involved - fungal or plant toxins, or even toxins in spices brought from India by a relative of the family. Chances are we will never discover the cause in this case. However, reading the increasingly confusing reports around the case does raise concerns that more extensive testing was not conducted at the time.

A further possible explanation might be provided by a Massey University PhD student's work.  Hayley Hunt of the Institute of Veterinary, Animal and Biomedical Sciences is investigating a rare disease in hunting dogs called Go Slow. The disease affects the dogs’ ability to walk by altering the mitochondria (energy-producing structures within cells), so that their muscles are no longer able to contract.  She says the likely cause of the disease is dogs eating wild pig meat that has been poisoned when the pig eats particular plants. The identity of the plant and toxin that may be tainting the pig meat is currently unknown and may be difficult to define, as there are so many possibilities.

Raw water: Is it bullshit?

There is a new fad spreading rapidly in the US.  "Raw water" is the latest craze for health fanatics keen to spend serious money.

What is raw water?  Its proponents claim it is water as nature intended it - unfiltered and untreated, containing minerals from the water source and no chlorine.  One raw water company claims that "all other bottled, filtered, tap, and even spring waters are sterilised with ozone gas, irradiated with UV light, and passed through a submicron filter" and that "blasting water with ozone changes its molecular structure".  Clearly, there is some truth in this statement, but also a lot of nonsense.

Some water sources are indeed safe to consume untreated; others may appear to be so, but are not safe.  In August 2016, over 1000 residents of Havelock North in New Zealand became ill after consuming drinking water from two bores operated by the local council.  Investigations showed that the affected residents had been infected by Campylobacter.  This was not the first time that the bore heads had been found to be contaminated.   The outcome of an extensive investigation was that the water in the bore heads was contaminated with water from an adjoining farm pond on land that had been inundated by heavy rains.  The aquifer was not contained and when the pumps were turned on, water from the pond, probably contaminated with sheep faeces, was drawn into the town supply.  Anecdotal evidence says that the level in the pond dropped when the pumps were turned on.  An immediate response was to chlorinate all water supplied in the area, which annoyed some residents, and the two affected bores were closed.  Water was drawn from other bores in the nearby Hastings area and  the supply has been chlorinated.

I am constantly surprised by people who want to turn back the clock to a time when food and water borne diseases were common, before modern scientific and technological advances made our lives much safer.  Campaigning to ban chlorination of town water is one of those issues.  Consumption of raw milk is another one of those desires that can lead to illness.

However, I am also reminded constantly that many rural areas are not serviced by mains water and wastes are treated on site in septic tanks, then discharged to the land.  Our house on our own lifestyle farm collects water from the roof and stores it in 36,000L tanks.  There is no filtration, chemical or UV treatment.  We, like many other rural dwellers, are thereby deliberately exposing ourselves to risk, though there is no alternative other than boiling water or buying bottled water for drinking.  The only thing I can say is that since moving to the farm over 30 years ago, we have never suffered from gastrointestinal illness.

Where does this leave us?  Treated tap water is probably the safest water supply.  Experience shows that rural tank water is usually safe, though it is not sterile; provided that the tanks are protected from contamination by animals or from septic tanks, there is little to fear from drinking it.  The perceived benefits of bottled raw water may be illusory, and the marketing hype criticising filtration and ultraviolet treatment of spring waters is just plain misleading.  Those getting the most benefit from bottled raw water are the suppliers.




Tuesday, December 12, 2017

Wild meat and botulism? Confusion reigns.

Recently in New Zealand, a family became seriously ill after consuming wild boar.  Authorities have said that the meat is suspected of being contaminated with botulin toxin.  Botulin is one of the most toxic substances on the planet.

I am somewhat confused by the reports - botulin toxin is produced by Clostridium botulinum growing in very low oxygen conditions.  The toxin is heat labile, i.e. it is destroyed by heating.  Apparently, the family ate curry made with the meat, and I would have expected the toxin to be destroyed by the cooking.  The family was reported to have collapsed within minutes of consuming the meal.  I'm not going to be dogmatic about this, but the toxin acts by binding to the nerve synapses, preventing release of actyl choline and thus blocking nerve impulse transmission.  Absorption of the toxin in the gut and transport to the synapses normally takes several hours, so the reported immediate collapse of the family is surprising.   As far as I am aware, there is no information on how long the cooked curry was held before consumption.  Spores of C. botulinum are extremely heat resistant, so if the curry were kept warm for a length of time before consumption, the spores could have germinated and produced toxin, though this implies quite a long time between cooking and consumption.

Health authorities have taken samples for testing and these have been sent to Australia - the tests are not simple, and results may not be available for several weeks.  However, the family is recovering in most cases, and anti-toxin has been administered.  Normally, recovery from botulinum intoxication takes weeks or months, not days.

Meanwhile, Ruapehu District Council has issued a warning over the health and safety of hunted and home kill meat.  It is illegal to sell hunted and home killed meat, but it can be shared with family, friends and visitors.  Again, this is confusing - if it can be legally consumed in this way, then there is no safety issue; it's a matter of regulations designed to ensure that meat offered for sale has been properly processed in an approved premises.  Further confusion arises because hunted and home killed meat can be consumed on a marae for traditional activities, but commercial operations on a marae must use commercially processed meat.

It seems to me that the toxicology report must be made available before conclusions can be drawn on the cause of this disaster for the family, and that reporters and regulators should be very careful to get their facts straight before publishing statements that can confuse the public further.