Got the munchies?

 Hands up anyone who, at any time during their lifetime, has scraped the cake mixing bowl and eaten the residues, or eaten raw cookie dough.  Yes, I see a lot of you with your hands up!  In a survey by Ardent Mills, Minnesota, 73% of respondents admitted to eating raw homemade cookie dough and 57% allowed children to lick the bowl and spoon after mixing cakes, while 65% admitted to eating store-bought cookie dough without cooking.  In a 2009 outbreak of Escherichia coli O157 food poisoning in 30 U.S. states, 77 patients, mostly young females contracted the illness and 35 were hospitalised.  A common factor revealed in the investigation was consumption of commercial raw cookie dough produced in a single plant.  As a result, 3.6 million packages of ready-to-bake cookie dough were recalled.

I used to beg my Mum not to use a spatula to scrape all the mixture from the bowl.  Mum didn’t know much about food safety; she had no formal training and over the years had learned how to bake.  Many younger people are probably in the same boat.  Most of us know that you can possibly pick up Salmonella food poisoning from eating undercooked eggs or chicken, and that the foods likely to give you food poisoning include leafy greens and sprouts, raw shellfish and raw milk, though the latter usually ignites a flame war if you publish comments.

So if you are asked why you should not eat raw cookie dough, what will you say is the risk?  Salmonella in the uncooked eggs, right?  What about the flour?   In 2016, ten million pounds of raw flour were recalled owing to contamination with Escherichia coli.  That year, the U.S. FDA and Centres for Disease Control and Prevention investigated infections by E.coli O121 occurring across the country.  Some serotypes of this bacterium can produce Shiga toxins.  A great deal is now known about Shiga toxins, but for our purposes here, we can say that ingestion of the toxin results in abdominal pain and watery diarrhoea, but may also cause haemorrhagic colitis, which is far more serious.  

The April 23 edition of Morbidity and Mortality Weekly Report discussed multi-state outbreaks of E. coli O26:H11 infections linked to raw flour in 2019. The investigators initially thought that ground beef was the source of the infection - patients interviewed reported eating ground beef and leafy greens.  However, by the use of modern microbiological analytical techniques - Pulsed Field Gel Electrophoresis and Core Genome Multilocus Sequence Typing - they were able to show  that the STEC O26:H11 isolates were different from those strains that had caused the ground beef illnesses in 2018.

How does flour, which is dry and doesn’t support bacterial growth, come to be involved in E. coli food poisoning transmitted in raw cookie dough?  Wheat flour is grown outdoors and may be contaminated from soil or birds and animals.  Cattle and deer have no cell receptors for Shiga toxin, so may carry the toxigenic bacteria without ill effect.  The milling process generally doesn’t include a lethal process step, so E. coli and Salmonella can survive into the finished product.  These vegetative cells are killed during cooking, but may be present in raw dough and cake batter.

Heat treatment of flour has been used in the past to destroy pathogens, but is expensive and has a negative impact on the properties of gluten, potentially making the flour unsuitable for baking.  Various other treatments have been proposed, including cold plasma, electron beam and gamma irradiation, but these methods may meet with consumer resistance.

A company based in Ontario, Canada has recently developed an organic, non-thermal treatment for flour that is a liquid added at the tempering stage of milling.  However, as far as I am aware, this treatment is not yet used in commercial flour production.

What about making home-made raw cookie dough safe?  It is extraordinarily difficult to find information on how to pasteurise raw flour at home to make raw cookie dough treats.  One blogger has described home pasteurisation of flour, using a 1200 watt microwave oven to heat the flour to 71C with a 55 second treatment.  She based this treatment on advice from FDA and I estimate that the flour receives an F0 of around 4.  

FDA is now pushing the message “Don’t eat any raw cookie dough, cake mix, batter, or any other raw dough or batter product that is supposed to be cooked or baked” and “Follow package directions for cooking products containing flour at proper temperatures and for specified times”.
Indeed, some packages of flour in US now have a label warning consumers to “Cook before sneaking a taste”.

Still want to risk it?

Listeria in smoked salmon - again.

The Department of Health in Australia is investigating three separate cases of Listeriosis apparently associated with smoked salmon.  There have been two deaths and one

This is not a reason to stop eating smoked salmon, or even cause for a massive recall.  There is a couple of things we all need to know.

Firstly, no specific smoked salmon product has been recalled.

Secondly, the three cases were in three different states and occurred over the period 22nd February to 7th June.  i.e. they were well separated both in location and time.

Thirdly, and probably most importantly, all three patients were over 70 years old and had other health conditions that may have predisposed them to infection by Listeria.

This is a reminder that people who may be susceptible to listeriosis should avoid foods that are known to carry higher risk of infection.

See:  https://foodsafetywithjaybee.blogspot.com/2011/01/listeria-hysteria.html  and search the blog using keyword Listeria.

Mussels unsafe if eaten raw

Many people in New Zealand like to eat shellfish, such as mussels, raw.  The Ministry of Health and New Zealand Food Safety Authority (Te Pou Oranga Kai O Aotearoa) has warned consumers NOT to eat fresh mussels harvested commercially in Coromandel, an area of the North Island, without cooking them to at least 65C.

The culprit for the current food poisonings is probably Vibrio parahaemolyticus, a bacterium found in marine, coastal and tidal waters, and most commonly causes gastroenteritis.  It is not normally spread person to person, though poor personal hygiene, such as failure to wash hands after handling raw shellfish, could result in infections.

Symptoms usually occur within 24 hours of eating the infected food and include

• watery diarrhoea (occasionally bloody diarrhoea)
• abdominal cramps
• nausea
• vomiting
• fever
• headache.

Image from Pathogen Profile Dictionary

https://www.ppdictionary.com/bacteria/gnbac/parahemolyticus.htm

There is a feeling among some experts that Vibrio parahaemolyticus entered New Zealand in imported fish or shellfish.  Cross contamination in the markets then allowed its spread.

Helpful Guide to Food Safety and Kitchen Clean-up - guest column

As most readers know, I normally don't post comments that contain links to commercial sites.  I get quite of lot of these, and in most cases, the writers are just trying to get clicks on their own sites.

However, occasionally a message comes along with useful information.   I received an invitation recently to publish a guide to food safety and kitchen clean-up.  This came from Cleaning Building Services New York.

A Guide to Food Safety and Kitchen Clean Up

An essential part of preparing a meal is making sure to use the proper food safety techniques. Without proper safety protocols your food can become contaminated and pass along foodborne illnesses to whomever eats or comes in contact with it. The Centers for Disease Control and Prevention (CDC) states that 48 million Americans become sick from foodborne illnesses each year. Of those 48 million people, 128,000 are so sick that they need to be hospitalized, and 3,000 people even die from the foodborne illness. To prevent foodborne illness from happening to you or your family, it is important to practice food safety protocols while handling, preparing, and storing all of your meals.

Cleaning Up the Kitchen

Keeping your kitchen clean is an important step in food safety. After each meal, it is important to clean and sanitize all surfaces where food was prepared or handled. All surfaces should be washed thoroughly with hot water and soap. For a deeper clean the surfaces can even be washed with a diluted chemical mixture of 1 tablespoon bleach and one gallon of water. All cooking appliances used when preparing the meal should also be washed thoroughly inside and out. An important step that most people tend to forget about is cleaning out your refrigerator. You should be going through your refrigerator once a week to discard any expired items to prevent growing bacteria. Vegetables and Fruits should also be rinsed under water before being consumed to get rid of any pesticide residue. You should always clean your hands thoroughly after touching any raw meats or fish as well, this will help prevent transporting harmful bacteria.

Know Your Temps

Foodborne Illness is caused by harmful bacteria, some of the most common being Escherichia coli, Salmonella, and Staphylococcus. This harmful bacteria can be consumed by eating undercooked foods and can be prevented by making sure all food is being cooked to their accurate internal temperatures. This can be done by using a kitchen thermometer. Checking the internal temperature is especially important when preparing foods like meats, fish, poultry, and eggs. Before preparing a new recipe, be sure to research what temperatures your ingredients should be kept at to avoid them being in a danger zone for the harmful bacteria.

Food Organization

When buying food at the grocery store, look for broken seals and damaged containers before putting them in the cart. Also, be sure to check expiration or sell by dates to only purchase fresh and safe to eat foods. When cashing out in the register line, be sure that your meat or fish is packaged separately to avoid juices spreading onto your other foods. Separation is key when storing your foods away at home as well. You should always store raw meat or seafood below any other foods in your refrigerator and place them in plastic bags to avoid contamination. If possible, use different cutting boards and other cooking utensils for meats or fish and veggies. If not, be sure to clean them thoroughly in between each use. Doing this will lessen the chances of leftover bacteria being transported from your raw meats or fish to your cut veggies and fruits.

Source: Cleaning Building Services

Other material from this source will appear on this blog from time to time.

Declaration:  Safe Food Blog does not endorse Cleaning Building Services, not does it have any pecuniary interest in the company.

Happy and safe Christmas to you all

For us in New Zealand, Christmas Day is only 12 hours away.  It is summer and we will be having BBQs and parties outside.

Don't forget - if you are cooking outside on a fire or a BBQ, steak requires only to be cooked on the outside, as the inside of meat from a healthy animal is essentially sterile.  If the steaks are thick, make sure that the edges are also cooked.  However, meat patties have been made by blending together minced meat and possibly egg as a binder.  The inside of the patty is not sterile and so the patties must be cooked through properly.  Use a meat thermometer to be sure that the inside has reached at least 75C.  You can't judge whether the meat is cooked just by its colour.

I prefer not to cook chicken on the BBQ because it is difficult to ensure even heating.  However, if the BBQ has a hood, it is essentially the same as an indoor oven.  Ensure that the chook is cooked properly, again using a meat thermometer.  I also prefer not to put stuffing into the body cavity - it slows down the cooking process and it's difficult to determine when it's done.  Cook the seasoning separately.

Round our place, there are very rarely any leftovers.  However, make sure that food doesn't stay in the sun any longer than necessary.  Ham that has been handled may well be contaminated with Staphylococcus.  If eaten straight away, this is no problem, but if left at room temperature, the bacteria may grow, since all their competitors have been killed in the preparation process, leaving them free to grow in the salty favourable conditions.

Remember that several food borne pathogens can grow, albeit slowly, in the refrigerator, so use leftovers within a day or so.

Recent changes in legislation in New Zealand mean that driving after more than one alcoholic drink risks being charged with driving under the influence of alcohol.  Better to have a designated driver, or stay off the turps!

To all my readers, I wish a happy Christmas and an enjoyable New Year.

Food poisoning with a difference

The usual symptoms of food poisoning are vomiting, with or without diarrhoea, and sometimes fever.  Abdominal pain is also a frequent accompaniment.  Yersinia pseudotuberculosis doesn't fit this mould.

Since the beginning of September 2014, there has been a total of 124 confirmed cases and 18 suspected cases of Y. pseudotuberculosis in New Zealand.  I was asked by the Science Media Centre (NZ) to comment on this outbreak, and to provide a general overview of the bacterium, how it is transmitted in the food chain, and what the potential sources of the current outbreak.

Yersinia is a genus containing 11 species of Gram negative rod-shaped bacteria (the Gram stain is a relatively simple microscopy technique used by microbiologists to divide bacteria into convenient groups for study).  Three species of Yersinia cause illness in humans,  the most infamous member being Yersinia pestis, which caused the Black Death. 

The other two human pathogens are Yersinia enterocolitica and Yersinia pseudotuberculosis, the latter being much less commonly seen in infections.

The natural hosts of Y. pseudotuberculosis are rodents and sometimes other mammals.  Infection of humans normally occurs through consumption of foods contaminated with faeces or urine.  The outbreak currently occurring in New Zealand appears to be associated with bagged lettuce and raw carrots.  The full cause of the infections is still being investigated by Ministry of Primary Industry workers.

The symptoms of Y. pseudotuberculosis infection include fever and right-sided abdominal pain, which makes diagnosis difficult, since these symptoms are also seen in appendicitis.  The patient may have diarrhoea, but this is often absent.  Less frequently, long-lasting joint pain may occur.  Symptoms take 5 to 10 days to develop, so it is often difficult for the patient to remember what foods they had eaten that might have transmitted the infection.

Y. pseudotuberculosis is very well adapted to infecting humans.  The bacterial cells have a number of virulence factors, most encoded on a small transmissible piece of DNA called a plasmid.  The virulence factors enable the bacterial cells to adhere strongly to intestinal cells, and to evade the host’s normal defence mechanisms, while other proteins enable the bacteria to invade host cells.

The best way to avoid infection is probably to throw away bagged pre-prepared lettuce or shredded carrots that have been in your refrigerator for a while, and to prepare these items fresh as required.  Since Yersinia species are not heat resistant, they can be killed by normal cooking.  Be careful to maintain good kitchen hygiene, and avoid cross contamination of cooked foods from raw foods of any kind.

Survival in Antarctica

I hesitate to write this blog article in case someone misinterprets it.  So... DO NOT TRY THIS AT HOME!

I recently spent three weeks in the Taylor Dry Valley in Antarctica.  Conditions are relatively harsh, though we had excellent extreme cold weather gear, warm tents and double layer sleeping bags.  Approximately 19 scientists and several visitors, who stayed for a couple of days, shared a Polar Haven working tent - insulated wooden floor and heated by a diesel stove, with electrical power provided by a generator.  Conditions in the tent were quite crowded; we ate our meals in there, operated scientific instruments, and analysed data.

What does this have to do with food safety?

There is no opportunity to bathe or even wash hands and only the most primitive sanitation facilities are available.  Baby wipes are the main means of keeping clean.  Nineteen individuals cooked for each other and ate together.  We ate all meals with our own cutlery and plastic food bowls and all drinks were contained in thermally insulated cups. Washing up consisted of a wipe with a paper towel or a non-scented baby wipe.  Because of the extremely dry conditions, we attempted to drink 4 litres of water every day, and all water came from Spaulding Lake, which is fed from the glaciers.  (Incidentally, the water tastes wonderful!)  Everyone carried their own 1 litre drink bottle.

Nobody contracted food poisoning.  I had both a personal and a professional interest in this!

This feat was the result of a combination of extreme personal hygiene care, the environmental conditions, and our diet.

In our Antarctic Skills Training programme, the importance of personal hygiene was emphasised - the Taylor Valley is very isolated and not a place to get sick.  Besides the use of baby wipes, tubes or pump dispensers of hand sanitiser were available everywhere and most team members carried their own supply too.

All our food, other than the dehydrated material, was stored outside in insulated boxes in the shade.  The mean ambient temperature was around 0C, so no opportunity for bacterial multiplication.

Our meals were either hot - bacon, pasta, meat stew, risotto, hashbrowns (lots), curry etc. -  or preserved in some way, such as dried and canned - cereals, canned fruit, milk powder, biscuits, soups, chocolate, muesli bars, peanut butter, jam, hard cheese, English muffins etc.  Most meals therefore were cooked in the outside camp kitchen and eaten immediately.  There were never any leftovers or reheating, so again no opportunity for bacteria to multiply or produce toxin.

I don't recommend that anyone should eat or prepare food for others without washing their hands, but this experience does show that with the proper precautions, it is possible, even in primitive conditions, to maintain food safety.

Odd Spot:  Perhaps the highlight of our 3-week deployment in Taylor Valley came the day after we ran out of meat.  Two of the helicopter pilots secretly organised to bring 4 or 5 large pizzas on one of the resupply missions.  They were heroes!

Norovirus in a confined space

I am currently down at Scott Base, Antarctica, heading out into the field tomorrow for two to three weeks' scientific work.

The base is on high alert, but not because of weather or acts of terrorism etc.  The concern this time is the outbreak of norovirus at McMurdo Station, which is only just over the hill from here and is normally visited regularly by both scientists and service personnel.

We are taking extreme precautions; the Thursday night American Night has been cancelled and visitors are strongly discouraged if not completely barred.  There are hand sanitiser pumps throughout the base and it is a requirement to sanitise hands before entering the mess.  Communal food items, such as loaves of bread are not to be handled with bare hands, because the virus can easily be transmitted on surfaces.  The bathrooms and toilets are being regularly sanitised and there too, there are warning signs that hands must be washed with soap and water and hand sanitiser is freely available.

It is to be hoped that the virus doesn't make it over to Scott Base - there are several projects kicking off now, and many more scientific teams will be arriving shortly, to the extent that some teams are being asked to reschedule their time at Scott Base to free up bunk room space.  An outbreak here could be catastrophic for the scientific programme, not to mention the misery for the victims.

Raw milk linked with food poisoning in New Zealand

I have written several times about the hazards of drinking raw milk (see the label "raw milk").  Using Ministry of Health information obtained under the Official Information Act, Talia Shadwell has written about food poisoning linked with consumption of raw milk in the Manawatu and Waikato, two regions of New Zealand.

A total of nine people, including two young children, were hospitalised in March, suffering from Escherichia coli  infection.  A month later, six people contracted campylobacteriosis.  A common factor in all these cases was apparently consumption of raw milk.

What is of great concern to me is that these patients revealed that they had little knowledge of the hazards of drinking raw milk, despite the publicity given to such outbreaks.

I would uphold the right of individuals to consume raw foods if they so wish, but they should be fully aware of the risks and remember that their children do not really have the luxury of food choice.

TV chefs fail at basic hand hygiene

I have just watched famous TV chefs preparing demonstration dishes.  One worked in his kitchen, others in an outside setting.

In both cases, the chefs were handling raw meat with their bare hands and preparing salads and sauces.  At no point did the chefs wash their hands and of course, they were moving between raw meats, fresh vegetables and spices. 

Of most concern to me was the use of a towel.  Chefs often have a towel at their waist; they use it for wiping spills from plates prior to service.  On this occasion, the chef handled the raw meat and repeatedly wiped his hands on the towel.  The sauce was blended from fresh vegetables and was not cooked.  There were no hand washing facilities in the shot and the sauce vegetables were also handled with bare hands.  The potential for food poisoning is significant.

Now, perhaps the chefs really did wash their hands between handling raw meats and salads.  However, these are demonstrations for ordinary viewers.  They should be setting a better example and emphasising the necessity of hand washing.

Safe microwaving

My wife, who has been married to a food microbiologist for 43 years, mentioned something she read in a Q & A section of a local newspaper, in which the writer discussed whether microwave heating killed Salmonella.

The main effect of putting food into a microwave oven is to cause the water molecules in the food to absorb energy.  The molecules move faster and we register this as the food getting hotter.  (It can be shown, by careful experiments, that there is a small effect of microwaves per se on microorganisms, but the main effect is the result of the heating).

When salmonellae and most other vegetative cells reach 75C, some critical enzymes or other cell components, such as the cell membrane, are damaged and the cells die.  So the writer was correct in saying that microwave heating makes food safe.

However, there are a couple of provisos.  First, it is essential that the food reaches this temperature throughout.  Some microwave ovens have hot spots, so the food may appear to be boiling, but there may be areas where the temperature is much lower.  This can be alleviated by stirring the food a couple of times during heating.  Secondly, spores of pathogenic bacteria in the food will probably not be destroyed and may actually be activated by the heating.  If the food is consumed immediately, there is no hazard, but if it is then cooled and stored, the germinating spores can multiply and may cause food poisoning.  (In this regard, microwave heating is no different from stove top cooking).

Finally, when we think of food safety, we tend to think of food poisoning.  However, the microwave oven can superheat liquids above boiling point.  When the liquid is disturbed, perhaps by bumping the container, the superheated water can suddenly flash into steam, causing a painful burn.  A couple of my students have discovered this when using a microwave oven to heat microbiological culture media.

However, in my opinion, using a microwave oven to cook or to reheat food is just as safe as a conventional stove.

Don't be an Alice

In Lewis Caroll's Alice in Wonderland, Alice found that taking a bite out of a mushroom would make her grow very tall; the other side made her shrink.  At one level, this is a childrens' tale, or at another it could be argued to be about taking hallucinogenic drugs.

Unfortunately, if you don't know what you are doing when it comes to eating mushrooms, you can wind up taking a different kind of trip - to the hospital or the mortuary.

There are many mushrooms (fruiting bodies of fungi) that can be eaten.  At this time of year in New Zealand, the mornings are often damp and we see mushrooms and toadstools popping up all over the place.  In my opinion, field mushrooms, Agaricus campestris, have a much better, stronger flavour than cultivated mushrooms bought from the supermarket.  They are a delight to collect and eat and I have spent many hours walking around our small farm searching for these delicacies.

But how can you tell if a mushroom is safe to eat?  My grandfather told me that you should cook them in cream and eat them on toast for supper.  If you woke up in the morning, they were edible!  This is NOT the way.  Neither is peeling and cooking a way of making mushrooms safe - the toxins of many poisonous fungi, such as the Amanitas are not destroyed by heating. 

The only safe way to know if a mushroom is edible is to have a good knowledge of their appearance and where they are found.  There are guides to help you identify mushrooms and toadstools, but to the untrained eye, many different species look the same.  If you aren't sure, don't eat!

Even the terminology is open to interpretation.  Strictly, the word ‘mushroom’ refers only to the genus Agaricus.  The cultivated mushrooms sold in the supermarkets are usually the white buttons of Agaricus bisporus, though we do see other varieties, such as the large browns. The word 'toadstool' is then used to describe any other fruiting body with a cap and stem that appears different from Agaricus, often implying that it is poisonous.

I took the following from an ABC report that followed the death this week of a Chinese visitor to Australia who appears to have eaten Death Cap (Amanita phalloides) toadstools:

History:

• Death cap mushrooms are considered the most poisonous in the world and one is enough to kill an adult human.
• At least six people have died and at least 12 made sick from eating death cap mushrooms in Australia in the past decade.
• Death caps have been involved in the majority of deaths around the world from mushroom poisoning, including that of Roman emperor Claudius.

Appearance:

• Death cap mushrooms are similar in appearance to several species of edible mushrooms commonly used in cooking, such as paddy straw mushrooms and Caesar's mushroom.
• Death caps may be white but are usually pale green to yellow in colour, with white gills and a white or pale green stalk up to 15cm long. (See image below from Wikipedia)
• The entire mushroom is poisonous and cooking or peeling the mushroom does not remove toxicity.

Symptoms:

• Death caps are said to taste pleasant and symptoms can occur six to 24 hours after consumption.
• Initial symptoms can include abdominal pain, diarrhoea, vomiting, hypotension and jaundice, followed by seizures, coma, renal failure and cardiac arrest.

Habitat:

• Death cap mushrooms can be found in parts of south eastern Australia, particularly ACT and parts of Victoria.
• They are commonly found near established oak trees and some other hardwood trees and are most common during later summer to early winter after heavy rain or irrigation.
• It is thought death caps were introduced to Australia with the importation of different hardwoods.

Treatment:

• Death caps are extremely poisonous and if consumed it is a medical emergency.
• Anyone who suspects they have eaten a death cap should seek immediate medical attention and where possible take a mushroom sample for identification.  

There are approximately eight toxins in A. phalloides, the major ones being α-amanitin and β-amanitin, which inhibit RNA polymerase.  This prevents protein synthesis, resulting in the death of cells.  The liver is usually the first organ to be damaged, often irreparably, and later the kidneys.

Picture of Amanita phalloides from Wikipedia:  http://en.wikipedia.org/wiki/Amanita_phalloides


Have a look at Peter Valda's comments on mushrooms and toadstools:

http://www.burkesbackyard.com.au/1997/archives/27/in_the_garden/gardening_tips,_books,_techniques_and_tools/mushrooms_and_toadstools

Don't always blame the chicken - it spoils my sleep

"The human understanding when it has once adopted an opinion ... draws all things else to support and agree with it. And though there be a greater number and weight of instances to be found on the other side, yet these it either neglects or despises, or else by some distinction sets aside or rejects".   Francis Bacon, 1620.

A few years ago, I was flying from Hong Kong to Auckland.  I sat with two attractive young women and enjoyed a glass of champagne with them before dinner.  After the meal and film, the girls went off to spend time with other members of their party and I settled down for a sleep.

Some time during the flight, the cabin attendant shook me awake: "Dr. Brooks.  Are you a real doctor?".  Suppressing the urge to take him by the throat and educate him about academic qualifications, I asked what was the problem.  It seemed that one of the girls and two others of their party had been taken seriously ill, and the attendant wanted me to open the airliner's medical pack to use the rehydration fluids for the victims.  I explained that I was not qualified to do this and headed off to the galley to chat to the stewardess and persuade her I was really in need of a beer and some sandwiches.

Some time later, the girl who was not ill told me that her friends were vomitting and had diarrhoea.  "It was the chicken pizza we had in the lounge before we boarded".  The timing and symptoms didn't seem right to me and I asked a few questions, including what they had been doing in China.  "Oh, we've been at a furniture expo for the last week".  It didn't seem to occur to her that she had been snacking on canapes and eating buffet-style meals for the previous seven days; she immediately blamed the chicken.  When we landed, her friends were taken by ambulance to the hospital, suffering from severe dehydration. I never heard from them again, but my money is on the meals during the week, not the chicken.

Now whenever I fly international, I ensure that my ticket is booked in the name "Professor Brooks".  I'm more likely to get a decent sleep during the flight.

Hello, how are you, is it seeds you're looking for?

It's all over, bar the shouting.  Or is it?

As at 30th June, 2011, there were 50 reported deaths from the Escherichia coli O104:H4 outbreak centred in Germany.  Cases of illness have been reported from 16 countries, not all victims having travelled to Germany.  This suggests that there may have been some person-to-person infection, though in at least one case, there appears to be none of these links.

Thankfully, the number of cases reported is dropping, the outbreak following a classic curve of increasing number of cases, followed by a decrease once reporting shows that there is an outbreak under way and information and preventative measures become available.

European scientists and government sources have suggested that  fenugreek seeds imported from Egypt in either 2009 or 2010 are implicated in the outbreaks in Germany and Bordeaux.  Epidemiological investigations do link these particular sprout seeds with the outbreaks.  But a link is not proof.

Not surprisingly, the Egyptians have objected to their seeds being blamed for the outbreak.  I have some sympathy with them - as far as I am aware, O104:H4 has not been isolated from any seed samples.  If these seeds are the source, then we have another problem on our hands.

If the seeds were imported to Germany and France, and perhaps other countries, the implication is that any E. coli O104:H4 present in the seeds survived for between two and three years before the sprouting process allowed them to multiply and cause the outbreak.  This raises a number of questions:  is this strain of E. coli particularly hardy, so that it can survive for years in dry seeds?  Were all the infected seeds exported from Egypt?  If not, were there any O104:H4 cases in Egypt between 2009 and the present?  If there were cases, why have we not heard about it?

I don't believe that we have heard the last of this by a long chalk.

Colonel Mustard, in the Dining Room, with the Sprouts

The last couple of weeks have been like the old game of Cluedo, with everyone running round accusing various participant of foul play and trying to find the culprit.  It would be amusing if it were not so deadly serious.

It now appears that the outbreak of Escherichia coli O104:H4 in Germany, which has now reached 16 countries, was probably caused by fresh vegetable sprouts grown in a farm in Uelzen, near Hamburg.  Unfortunately,  cucumbers from Spain, lettuces and tomatoes also had the finger pointed almost indiscriminately at them.  That caused huge financial losses for the suppliers and had knock-on effects on vegetable sales throughout Europe.  In some ways, I can sympathise with the authorities and the media.  This is one of the largest and most serious outbreaks of food poisoning ever and finding the source as quickly as possibly was imperative.

At the time of writing, there have been 3517 cases of EHEC infection, resulting in an unprecedented 839 cases of Haemolytic Uraemic Syndrome and 39 deaths.  The rate of new case reporting has slowed, but it is likely that more people will become ill before this is all over.

This shows just how difficult it is to pinpoint the source of an outbreak of food poisoning in our highly integrated and widespread food supply chain.  The sprout farm purchased seeds for sprouting from both European and Asian countries.  The seeds were sprouted, using what seems to be standard and well designed conditions, and the 18 different sprout mixtures were sent to many different points in Germany.

The German authorities have been accused of being in disarray and having no proper response prepared.  There may be some truth in this - if the responsibility for food safety is spread across many local authorities and agencies, setting up a coordinated and timely response is fraught with difficulty.  But it is generally recognised that epidemiological investigations may have a success rate as low as 33% in tracking down the source of infections and the chance of success falls as time goes on.

At times like this, we often hear calls for increased testing of products before they are released onto the market.  Good try, but no cigar!  For a number of reasons, microbiological testing to assure safety of food is just not possible.  Testing is expensive and time consuming.  In some cases, the testing period exceeds the shelf life of the product.  A simple statistical calculation shows that when contamination levels are low, the number of samples that must be tested to get even a 95% chance of detection is prohibitively large and even then, 5% of contaminated samples will be accepted as safe.  Testing for E. coli O157:H7 would not have picked up the German strain and even proposed widened testing for "The Big Six" Entero-Haemorrhagic E. coli strains would have missed this one.

Regulators must be strong in the coming months.  Microbiological testing gives only a retrospective view and a poor one at that.  Imposing increased mandatory testing will not assure the safety of foods.

The only way we can ensure the safety of our food supply is to introduce controlled lethal steps in processing, such as heating or irradiation, or to put in place rigorous control of every potentially hazardous ingredient, process step, processing facility and distribution chain.  This is particularly important with high risk products such as sprouts.  What every food producer and distributor needs is a Hazard Analysis based Food Safety Programme of Risk Management.

Sarah Carter - confusion reigns

On 12th March, 2011, I wrote about the tragic death in Chiang Mai of Sarah Carter.

Originally, her death was blamed on consumption of toxic seaweed.  At the time, I suggested that this was a highly suspect conclusion, based on the symptoms and the circumstances.

A short while later, it was claimed that Sarah and her two friends had been infected by an ECHO virus.  The symptoms matched.

However, more information came to light - a Thai tourist guide had died in the next room in the same hotel and a week earlier, two other tourists had died in a room one floor below. 

The New Zealand TV3 channel discovered that a total of seven tourists had died in Chiang Mai in similar circumstances.  Sara Hill, an investigative reporter for TV3, went to Chiang Mai and made a programme screened here a couple of weeks ago.

In an interview with Sarah Carter's friend, Sara Hill discovered that none of the three girls had eaten seaweed and had eaten two different meals.  They all developed sore stomachs and vomiting and were hospitalised.  According to a Thai cardiologist, Sara Carter suffered very low blood pressure, dehydration and low blood flow to the kidneys, with ultimate kidney failure.

The reporter managed to obtain swab samples from the room occupied by Sarah and returned them to New Zealand for testing.  Traces of chlorpyrifos, an organo-phosphorus insecticide used in corn and cotton farming, were found in the swabs.  Dow Chemical Company voluntarily withdrew the registration of chlorpyriphos for domestic use in 2001.  Mr. Ron McDowell, a UN scientist, hypothesised that Sarah had been exposed to chlorpyrifos as a result of over-zealous spraying of the hotel room to control bed bugs by a pest control operator.  McDowell claimed that the symptoms and pathology all fitted with chlorpyrifos poisoning.

However, the swabs were taken three months after the room was occupied by Sarah, so spraying could have occurred at any time during those three months. The report form was shown in the programme.  The level in Sarah's room was given as <0.1 microgram/sample, which probably means "below the limit of detection".  A sample from an air conditioner was 0.24 micrograms/sample, but the film of the sample being taken suggested that the area swabbed was uncontrolled.

The half life of chlorpyrifos in the human body is about one day, so, although it is absorbed quickly, it also disappears from the body quickly.  Thus tests at the hospital may not have shown its presence in Sarah's body.

I'm not convinced that we are much further forward.  The Thai authorities were not being particularly cooperative with the TV3 investigation and recently refuted the chlorpyrifos theory.  Three toxicologists in New Zealand have issued a statement criticising the programme and the conclusions drawn by the experts consulted by Sarah Hill.


It looks as though seaweed is off the hook and food poisoning seems a bit unlikely, as the three girls ate different meals, but suffered similar symptoms not commonly seen in microbial food poisoning.  Food contamination is not completely ruled out, as several meals could have been contaminated with a chemical.

I don't know if we will ever know the true story

Tasty but occasionally dangerous

If I asked you to name a food group that might be implicated in food poisoning, you would probably respond with "meat".  I did a survey (n=1) at home today and got that answer.  My wife thought a bit longer and said "Custard, but that's only because you have influenced me over the years".

Baked goods probably don't spring to mind as potential carriers of food poisoning bacteria.

In the last week, there have been reports from Rhode Island of zeppole, or St. Joseph's Day cakes, causing food poisoning by Salmonella.  I had never heard of zeppole before this report, but they are apparently popular in Italy, Sicily and Malta and in the Italian-American communities in the United States and date from the early 19th century.  They are deep-fried dough balls, or sometimes choux pastry, topped with powdered sugar or filled with custard, pastry cream or a mixture of butter and honey.  They sound delicious, though perhaps dangerous for the figure!

At the time of writing, there have been 76 cases and 29 hospitalisations.  Two people have died from Salmonella-associated illness.  It is too soon to say how this happened, but the possibilities include a carrier of Salmonella working as a food handler, or the use of ingredients contaminated with Salmonella.  The deep-fried pastry would probably be sterile immediately after frying, but could be contaminated by the food handler during the filling process.

Breads, fruit cakes and biscuits are usually pretty safe by virtue of low water activity, but filled pastries receive quite a lot of handling, while real cream may be contaminated with bacteria that rapidly grow under abuse temperatures to the point where they can cause food poisoning, either by infection or intoxication.

Will spoiled food make you sick?

I recently received a message from Jo, asking me to comment on this subject.  Jo actually raised a lot of questions and, of course, the answers are not simple.

First question:  If the food smells off, tastes bad, has a poor colour etc. is that a good indicator it will make you sick?

Humans have been on the Earth for a long time and one of the reasons they have survived for so long is that they have evolved self preservation mechanisms.  If the food smells off or doesn't look right, there is a chance that it is poisonous in some way and we tend to avoid it.  Sometimes I wonder what the first people to taste durian or blue cheese thought they were doing!  So, clearly, the answer has to be a qualified "Yes, it might make you sick, but some sort of tribal wisdom suggests that a few foods can look and smell awful but still be OK to eat".

Jo then went on to say that she thought that the food was unlikely to make you sick, as the changes were caused by spoilage bacteria and enzymatic reactions, which are not the same as pathogenic bacteria, which she thought do not alter the food in the same way.

This is where it gets complicated.  Spoilage bacteria do cause some changes, which, by definition, make the food unacceptable to most people.  Other bacteria, such as Salmonella, may grow alongside the spoilage bacteria.  When the food is eaten, the salmonellae  set up an infection in the gut and produce the familiar food poisoning symptoms.

Second question: Is it true that pathogenic bacteria don't alter the food?  Again, it depends on the bacteria.  Generally, clostridia alter the food a lot, producing many smelly compounds and gas.  This would put most people off eating the food, so they would be safe.  But some Clostridium botulinum strains are non-proteolytic.  That is, they don't break down proteins and they don't produce the foul smells that the proteolytic strains make.  So you could find improperly processed canned foods that appear quite normal, but could kill you.

Jo's third question was perhaps the most fascinating: she was most interested in how the food could potentially have both types of bacteria on it near to the time it was made and correctly identified contamination of the food as the cause, possibly by cross-contamination from some source.  A good example would be a careless food handler.

At this point, the food could cause food poisoning if consumed - Salmonella transferred from raw meat to a cream pastry would be a good example here.

Jo went on "However as time goes on and assuming the food gives them all the things they both need to grow, is it as simple as the pathogens might be around for a short time until the spoilage guys, who being better competitors for resources, take over; so by the time the food
is showing signs of being spoiled, the pathogens have been killed off?"

That's a really insightful comment.  Many fermented foods are actually safe because of this pattern.  Take raw cabbage and make sauerkraut:  we shred the cabbage and add about 2.5% salt to it and then press it into a container and seal it.  The salt draws out the tissue fluids from the shredded leaves and bacteria naturally on the leaves begin to produce lactic acid.  If we sample on the first day, we can find all sorts of bacteria, including Escherichia coli and possibly Salmonella.  However, as more acid is produced, the pH falls and the potential pathogens die off.  Finished sauerkraut has a pH around 3.1 to 3.7 and is perfectly safe to eat, though there has been a lot of bacterial growth in it.

So, to return to Jo's original question, "Is spoiled food potentially safe to eat, even though it looks and tastes awful?"    Sorry Jo, I can't answer that.   But if it tastes awful, why would you want to eat it?

One last point:  there is an anecdote that a lady opened a can of peas and thought that they looked a bit different.  She tasted one and cooked the rest.  She died of botulism.  Ironically, if she had cooked them and then tasted one, she would have lived, as the botulin toxin is heat labile.  I don't remember where I read this - it was somewhere around 1980, but it's a good example with which to finish this article.

Toxic seaweed was a red herring

The tragic death of beautiful Kiwi backpacker, Sarah Carter, in Thailand last month was initially blamed on a meal containing toxic seaweed.  Sarah and two other women suffered vomiting and heart complications while they were staying in Chiang Mai.  Privately, I thought that this explanation was highly unlikely, partly because of the symptoms and partly because it appeared that only these three were poisoned.

It now seems that Sarah had been infected with an ECHO virus.  These Enteric Cytopathic Human Orphan viruses are found in the gastrointestinal tract and primarily cause disease in children.  (Their name originated in the 1950s, when cell culturing allowed the viruses to be identified, but no disease was associated with them). 

ECHO viruses are highly contagious and exposure to them can result in an infection of the lower intestine, which then spreads to other organs.  Death is usually the result of overwhelming liver failure or myocarditis (inflamation of the heart muscle).

Because of their association with the gastrointestinal tract, ECHO viruses are usually transmitted by unhygienic conditions and person-to-person transmission via the faecal-oral route.  Respiration of infected droplets and contact with fomites (contaminated objects) may also be important in transmission.  I believe that it is significant that three other people died of heart problems in the same hotel in the space of two weeks, though a doctor from the Thailand Department of Disease Control said that the elderly British couple who died both had blocked arteries.

I guess that the messages we can take from this tragedy is that foreign travel is wonderfully mind-broadening, but that visiting areas where environmental and food hygiene are poor can be hazardous to health.  We should be careful, however, before thinking that Asia is the only
place we can contract ECHO viruses - poor hygiene can be found in any country.

Where's my PhD student?

I had a scheduled meeting with my PhD student this morning, but she didn't turn up.  I got a somewhat graphic text message, saying that she had food poisoning.  It seems that she, her partner and two friends went out for dinner in a restaurant in Auckland on Saturday.  They all appear to have food poisoning.

Of course, this doesn't prove that the restaurant was responsible.  Indeed, her description of the symptoms and time of onset make me wonder if another common source was involved.

However, a TVNZ One News investigation shows that on average, one Auckland food establishment per week has been shut down this year because of safety or cleanliness violations.

http://tvnz.co.nz/health-news/shocking-food-hygiene-figures-auckland-3800902

An Auckland City Council Environmental Health spokesperson said that the increase in closures was a result of tougher action by health inspectors in response to unsatisfactory performance and suggested that this was partly because of the economic recession - companies were selling food that would previously have been thrown out.

A disturbing statistic given in the TVNZ report is that over 100 restaurants and cafes are still operating, despite poor hygiene ratings, though to be fair, businesses are given the opportunity to clean up their act before being closed down if they don't improve.

This report begs the question "If inspectors had previously found unsatisfactory conditions in food outlets, why didn't they close them down at the time?  What has changed in the requirements to serve wholesome, safe food in clean premises?"