The global foodborne disease crisis

Recently, a virulent strain of enterohaemorrhagic E. coli caused around 50 deaths and sickened more than 4000 across Europe, the majority in Germany. The source of the infections is believed to have been organic fenugreek sprouts grown from contaminated seeds. As a result of this deadly outbreak, new regulations, improved surveillance and disease prevention strategies, particularly pertaining to produce, will likely emerge throughout the world.

Dr John Brooks, Professor of Food Microbiology at AUT University, said, “The outbreak of E. coli food poisoning in Germany is one of the worst outbreaks on record and certainly one of the most deadly. Our modern food supply chains are extremely complex. Foods are sourced from all over the world, so finding the source of this outbreak as quickly as possible was imperative.”

But what is an outbreak?

There are usually six potential causes of foodborne illness outbreaks: contaminated ingredients, inadequate storage and refrigeration, insufficient cooking, cross-contamination from raw products to cooked products, inadequate hygiene facilities for staff, and poorly trained and supervised staff.

Detecting an outbreak is the first challenge. One way health officials find outbreaks is through public health surveillance. By gathering reports of illnesses, statisticians can predict how many illnesses can be expected in a given time period in a given area. If a larger number of people than expected appear to have the same illness in a given period and area, it’s called a cluster. When an investigation shows that ill persons in a cluster have something in common to explain why they all got the same illness, the group of illnesses is called an outbreak.

The globalisation of food sourcing and supply adds an extra layer of complexity. While produce, meat and dairy may come from a local farm, the livestock may have received vitamins or medication from one part of the world and the fertiliser used to grow crops from another. An outbreak which involves hundreds of people being ill can be missed if the people are spread out over a wide geographic area.

In Australia, notifiable gastro-intestinal diseases include: Botulism, Campylobacteriosis, Cryptosporidiosis, Haemolytic uraemic syndrome (HUS), Hepatitis A, Hepatitis E, Listeriosis, Salmonellosis, Shiga toxin-producing/verotoxin-producing Escherichia coli - STEC/VTEC, Shigellosis and Typhoid. Doctors and microbiologists in each state must report infections that are on the list of notifiable diseases when they diagnose them in patients.

After an outbreak has been postulated, the hunt is on to identify the source of the infections. This is not always simple or straightforward. For example, the incubation time between exposure and symptoms for E. coli infection ranges from three to 10 days. After 10 days, patients frequently have difficulty in remembering what they ate and any leftovers have often been destroyed, making sampling and testing very difficult. Also, as pathogens are often not evenly distributed through the food, even extensive sampling can miss the pathogen, especially if only a low load is required to make consumers ill.

Imposed testing won’t guarantee food safety

Frequently, consumers demand that all foods and beverages should be tested prior to their release. This is both naive and unfeasible and would not prevent all outbreaks of foodborne disease because:

• Testing is expensive and time-consuming; and in some cases, the testing period exceeds the shelf life of the product.
• Even if the actual suspected food is available, the pathogen may be hard to find. It may have decreased in number since the outbreak. Other organisms may have overgrown it as the food has started to spoil.
• The pathogen may have been in only one portion of the food. A sample taken from a portion that was not contaminated will have a negative test result. So, a negative result does not rule out this food as a source of illness or the cause of the outbreak.
• Leftover foods or foods in open containers may have been contaminated after the outbreak or from contact with the food that actually caused the outbreak.
• Some pathogens cannot be detected in food because there is no established test that can detect the pathogen in the suspect food. In the German outbreak, testing for the usual STEC, E. coli O157:H7, would not have picked up the E. coli strain that was responsible for the illnesses.

Tracking down the source of infection through epidemiological investigations may have a success rate as low as 33%, claims Brooks. “This shows how difficult it is to pinpoint the source of an outbreak of food poisoning in our highly integrated and widespread food supply chain.

Contamination of foods and beverages can occur at any time from the farm to the fork. Some examples of typical contamination points follow.

Examples of contamination during production:

• If a hen’s reproductive organs are infected, the yolk of an egg can be contaminated in the hen before it is even laid;
• If the fields are sprayed with contaminated water for irrigation, fruits and vegetables can be contaminated before harvest; and
• Fish in some tropical reefs may acquire a toxin from the smaller sea creatures they eat.

Examples of contamination during processing:

• If contaminated water or ice is used to wash, pack or chill fruits or vegetables, the contamination can spread to those items;
• Peanut butter can become contaminated if roasted peanuts are stored in unclean conditions or come into contact with contaminated raw peanuts; and
• During the slaughter process, pathogens on an animal’s hide or intestines can get into the final meat product.

Examples of contamination during distribution:

• If refrigerated food is left on a loading dock for long time in warm weather, it could reach temperatures that allow bacteria to grow;
• Fresh produce can be contaminated if it is loaded into a truck that was not cleaned after transporting animals or animal products; and
• The contents of a glass jar that breaks in transport can contaminate nearby foods.

Examples of contamination during preparation:

• If a food worker stays on the job while he or she is sick and does not wash his or her hands carefully after using the toilet, he or she can spread pathogens by touching food;
• If a cook uses a cutting board or knife to cut raw chicken and then uses the same knife or cutting board without washing it to slice tomatoes for a salad, the tomatoes can be contaminated by pathogens from the chicken; and
• Contamination can occur in a refrigerator if meat juices get on other items that will be eaten raw.

Long-term prevention of foodborne outbreaks takes the actions of many partners in the food production chain, stretching from farm to table. Some prevention measures include:

• Quality assurance programs at egg and other farms;
• Safe agricultural practices for produce farmers;
• Efforts to keep shellfish harvest beds free of sewage contamination;
• Inspection systems at meat processing plants;
• Use of pasteurisation, canning, cooking, irradiation and other steps to kill pathogens in food processing;
• Buyer specifications for food safety in food purchasing contracts;
• Training for restaurant managers and food workers about food safety and sanitation measures, proper handwashing procedures, and the importance of giving food workers paid sick leave; and
• Food safety education for consumers.

Fallout

So far, the price tag on the outbreak in Europe is massive. Farmers experienced crop losses when they could not sell fresh produce as the hunt for the source of O104 jumped from cucumbers to lettuce and tomatoes before settling on sprouts.

Approximately 5900 tons of cucumbers, over 3200 acres of lettuce and 3500 tons of tomatoes had to be destroyed, according to Germany’s Agriculture Minister Ilse Aigner. And this is just destroyed produce - it doesn’t take into account the dramatic drop in sales of fresh produce following the outbreak. The European Commission in Brussels has put up 210 million euros or about $304 million to cover this but this sum won’t be nearly enough.

The US Centers for Disease Control and Prevention (CDC) estimates that a single fatal case of E. coli O157 (another Shiga toxin-producing strain of E. coli with similar effects to the one in this outbreak) costs approximately $7 million in medical expenses. Multiplying that by the number of deaths in this outbreak so far yields an amount of $350 million and that doesn’t include the costly treatment, including kidney dialysis, for the other 800 plus HUS cases who so far are surviving or medical care for the other 4000 who are infected.

Germany’s government-backed insurance companies have an annual budget of about 180 billion euros for both the university and regional hospitals. The outbreak has now blown such a big hole in those budgets that the German hospitals are not going to make it through the current year without a financial infusion.

A spokesman for the federation has estimated that treatment for E. coli patients requiring dialysis has already amounted to more than 20,000 euros per victim. Those who survive are looking at possible lifelong follow-up treatments for everything from kidney to neurological issues.

In the coming months, disease prevention strategies and surveillance techniques around the world will have to be reviewed and modified to accommodate the lessons learnt from this outbreak. 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.