"Food safety is first and foremost an issue of public health. However, it has connections with trade and commerce. The raising of concerns about food safety when no problem exists will harm livelihoods. Failure to draw attention to problems when they occur, an act of misprision ("treachery" ed.), will put food consumers at risk and will also harm livelihoods in the longer term". (D. Adams 1998).
Contamination of food and water is possibly the most widespread health problem in the world. Annually hundreds of millions of children younger than five years of age suffer from diarrhoea with 3 million dying as a result. Foodborne diseases are increasing throughout the world, in developing as well as industrialised countries (Dr. FK Kaferstein chief of the WHO Food Safety Unit, quoted by Ames (1993), despite the increase in our understanding of pathogenic organisms and their control.
The number of cases of foodborne illness in the USA alone per year has been estimated to be between 6.3 million and 81 million (Todd 1990) with associated costs up to $10 billion annually (Todd 1989). Annual costs in Australia are estimated at between $1 billion and $1.9 billion, a similar rate to other industrialised countries (Crerar et al 1996). It appears paradoxical that foodborne disease is increasing in industrialised countries. The factors involved in this increasing incidence are complex: new pathogens have emerged or been identified over the last 20 years, production and distribution systems for food have changed as have people's eating and cooking habits (Altekruse and Swerdlow 1996).
It is estimated that perhaps 97% of foodborne disease cases are caused by improper preparation of food immediately prior to consumption (Biddle et al 1997). The beef industry is in the business of producing food, a food that human enteric pathogens find to be a most suitable growth medium. As with any product, the industry must recognise its obligation to provide "Instructions for Use" on the best and safest ways to handle, store and prepare the product. The Australian meat and livestock industry began a campaign in 1997 to enhance consumer awareness of food safety emphasising the 3 basic food safety principles - adequate personal hygiene, avoiding cross-contamination and adherence to time and temperature controls.(Palmer 1998)
So why do we need to look beyond this food preparation by the consumer in our quest for food safety?
The responsibility for food safety should not stop there but should go right down the chain back to the production system/farm. Breakdowns in food safety can have disastrous consequences on public health as well as on the viability of the industry involved. As an example, the Garibaldi salami contamination holds many lessons for the meat industry. In early 1995, 20 children in South Australia were diagnosed with haemolytic-uraemic syndrome (HUS) associated with the enterohaemorrhagic E. coli 0111:H- in locally produced fermented sausage. Of these 20 children, one died, 18 required kidney dialysis, and 5 had significant kidney impairment 12 months after discharge from hospital (Henning et al 1998). Naturally this episode received considerable publicity in Australia because, although enterohaemorragic E. coli infections have occurred sporadically in Australia and have been the cause of even more devastating outbreaks particularly in the USA, this was the first severe outbreak in Australia. This had an immediate impact on the sales of packaged salami Australia-wide. In the first 5 months, sales dropped nearly 50% but more importantly the sales have not fully recovered and for the three subsequent 12 month periods, sales have averaged approximately 30% lower than for the 12 month period preceding the outbreak (M. Adams 1998). The source of the organism was believed to be contaminated mutton. This episode exemplifies the fact that product failure by one company can impact severely on consumer confidence, in this case in the consumption of smallgoods. Subsequent studies revealed there was a wide variation in the quality of product available and a wide range of manufacturing methods. The smallgoods industry worked with Government and scientific organisations to draft new standards for the fermentation of salami and develop Hazard Analysis Critical Control Point (HACCP) plans for this process as well as for each product and process in the manufacturing of all smallgoods. As a result many "below standard" small producers are no longer in business.
What biological agents are responsible for foodborne illness?
The biological agents responsible for foodborne illness are diverse and include bacteria, viruses, protozoa, fungi and toxins with bacteria being the most common cause. Bacterial pathogens associated with the consumption of meat products include Salmonella spp., enteropathogenic Escherichia coli, Listeria monocytogenes, Campylobacter jejuni and C. coli, Yersinia enterocolitica, Clostridium perfringens and Clostridium botulinum, Staphylococcus aureus, and Bacillus spp. Some of these organisms including Salmonella spp. enteropathogenic E. coli, L. monocytogenes, Campylobacter spp., and Y. enterocolitica, may be present in the production animal and he a potential source of contamination. The chain of events from killing, processing, storage and food preparation can allow multiplication or these contaminating organisms. Other bacteria such as C. botulimun, S. aureus, and Bacillus spp. are generally regarded as secondary contaminants that may contaminate the meat during processing, with some organisms (eg C. botulinum and S. aureus) producing toxins that cannot be destroyed by cooking.
Of the bacterial pathogens linked to the consumption of red meat, salmonella and enterohaemorrhagic E. coli (EHECs) are the most important in terms of numbers of people affected, salmonella being the most frequent cause. In contemporary times the greatest research interest has been in the EHECs but the importance of other pathogens particularly salmonella must not be overlooked. Animals carrying and shedding these organisms are not necessarily ill. With EHECs in cattle, clinical disease is only occasionally seen in calves. It is the animals not showing clinical illness that pose the greatest threat because they are the ones suitable for slaughter and therefore able to enter the food chain.
Back to the Garibaldi salami - What are enterohaemorrhagic E.coli?
EHECs are a sub-class of enteric E. coli that have been associated with epidemic and endemic diarrhoea, haemorrhagic colitis and haemolytic uraemic syndrome. The most notorious EHEC identified is E. coli 0157:H7. It has been the subject of considerable research.
How E. coli 0157:H7 has altered our perception of food dangers
The emergence of this organism and its impact on food safety have changed the perception that food poisoning predominantly causes a bout of vomiting and diarrhoea to the realisation that it can be life threatening or cause prolonged debilitation particularly in children and the elderly. This organism was first identified in humans in the USA in 1982 and has followed an epidemic spread since then, and has been identified throughout the world. In the USA E. coli 0157:H7 is estimated to cause 20,000 human cases of sickness and between 250 - 500 deaths annually. To date in Australia there has been a low occurrence in humans. Three of the notable outbreaks worldwide have been :-
It has been demonstrated that the ingestion of less than 10 organisms may cause disease. This low infective dose is in contrast to the high infective dose of many other foodborne pathogens. Extrapolating from this to modern production methods where large batches of mince meat are made, it has been estimated that there could be sufficient numbers of bacteria on a carcass contaminated with faeces, to affect 8 tons of ground beef. Product recalls can have a profound effect on profit and consumer confidence. In 1997 Hudson's Meats in the USA recalled 25 million lbs of hamburger mince following human infections. Mince is particularly susceptible because the mincing process drives surface organisms deep into the product. If cooking is insufficient, these organisms will not be killed whereas if they had been on the surface of a steak, the cooking of the surface would have destroyed them. Reduction in the number of these pathogenic bacteria being excreted by livestock could significantly raise the food safety quality of meat and therefore involves the producer, veterinarians and other advisers to be aware of food safety issues. This is currently a key area of research and recently published data demonstrates that a dietary change from grain to hay prior to slaughter can eliminate the shedding of the organism (Diet-Gonzalez et al 1998). Other research has focussed on survival and multiplication in the environment with drinking water troughs and feed being identified as important sites for this (Hancock DD 1998).
The largest known outbreak of foodborne illness in the world involved improperly pasteurised milk in the USA in 1985 in which there were 16,659 confirmed cases and up to 197,581 suspect cases with several deaths (Todd 1990). Australian figures indicate that nearly 40% of bacterial foodborne disease outbreaks over the last 15 years were due to salmonellosis. Historically S. typhimurium has been the most common cause of human salmonella food poisoning and still is in Australia (Murray 1994, Barton 1997) although in the northern hemisphere, S. enteritidis (from poultry but not in Australian poultry) is now more common. Occasionally salmonella infections will cause death or chronically debilitating arthritis. The geographical distribution of these bacterial pathogens has been observed to change with time and with salmonella has often been associated with the movement of contaminated animal feeds.
Salmonella typhimurium DT 104
This organism has yet to he detected in Australia. In North America and Europe public health and animal health agencies are becoming increasingly concerned with the emergence of this organism which is resistant to at least 5 antibtotic groups (6 in the UK). It is associated with higher hospitalisation and mortality rates among people than for other salmonella infections and, as expected, poses problems with antibiotic therapy. The organism has been present in the USA since at least the early 1990s. It has been associated with a number of animal species. In a study in the UK in 1995, there was a clear association between human illness and contact with farm animals particularly sick calves (Wall et al 1995). The emergence of this organism has highlighted concerns regarding the use of antibiotics in food producing animals especially when large volumes are used as growth promotants.
An exhaustive discussion of other bacterial pathogens is beyond the scope of this paper, but suffice it to say that there are many gaps in our knowledge of the carriage of these pathogens by domestic livestock and which strains are actually associated with human disease. Care must be taken in interpretation of animal data. There is a need to demonstrate that organisms detected in animals are indeed pathogenic for man. This is exemplified by yersinia where animal strains may not be pathogenic for man.
Mad Cow Disease ( Bovine spongiform encephalopathy or BSE)
The concerns about the possible association of BSE with aberrant Creutzfeldt Jakob disease in humans and the confirmation of this has had dramatic effects on the consumption of beef in the UK and Europe but has also affected Japanese beef consumption. Although BSE and the similar disease, Scrapie in sheep, do not occur in Australia, producers, veterinarians, other advisers, and Government authorities must be vigilant in investigating any behavioural abnormalities in cattle and sheep. Already, the European Community are setting monitoring levels in order to classily Australia as being free from BSE.
The beef industry not only produces beef but also produces manure and effluent
Manure and effluent are potential sources of contamination by enteric pathogens to crops and waterways. E. coli 0157 H7 has also caused food poisoning via juices, cider and sprouts. Animal manure has been implicated as the vehicle for contamination. A sound scientifically based understanding of the transmission in manure and effluent and best methods of control is required. Additionally we must take into account that many human organisms entering the environment can infect the animals we use for food. It is possible to reduce contamination of the environment by correct disposal of human waste (Johnston 1990). This is also an area of considerable scientific research.
What is HACCP?
The Hazard Analysis Critical Control Point System (HACCP) for food was originally developed to ensure food safety for American astronauts in the NASA space program. The aim was to identify the potential hazards for a particular food related to the nature of the raw ingredients and the process of manufacture and preparation, to identify those points in the process where stringent control would result in the most likely outcome of a safe final product, to decide what type of monitoring had to be put in place at those critical control points to ensure control was maintained, and to have a verification process to ensure the system was operating to requirements (Biddle el al 1997). The control of foodborne pathogens must be at all stages of food production from the farm to the abattoir, food handling, storage and preparation. HACCP systems are now being applied to abattoir and food-handling practices and in the future should also be applied to animal production systems.
Abattoirs in Australia have always been the most regulated sector of the industry with strict hygiene standards which up until recently were overseen by Government inspectors in all plants. More recently the domestic abattoirs have provided their own inspection under Government controls. The consequences of food safety concerns particularly related to E.coli 0157:H7 in the USA, have necessitated the adoption of HACCP plans. All Australian export plants were required to implement HACCP principles from 1st January 1997. The United States Department of Agriculture (USDA) developed a system of regulations for microbiological testing and sanitation in abattoirs. These were a requirement for export to the USA. These Mega Regs were operational in Australian export plants from the beginning of 1997. By mid 1997, routine HACCP plans were routinely operating within domestic plants. (Palmer 1998). The supermarket chain, Woolworths, ranks food safety as the number one customer concern and as such has developed the Woolworths Vendor Quality Management Standard, a HACCP based system to ensure the safest possible food from the supplier as well as the safest methods of handling and storage at the retail store.
HACCP systems need to be dynamic. Examples of this need are the banning of feeding mammalian meat meal to ruminants as a result of the evolution of BSE, and development of guidelines for the fermentation process in the production of salami because of the acid tolerance of enterohaemorrhagic E. coli. The HACCP system also needs to be relevant to local conditions and pathogens, streamlined and financially feasible.
Control of the microbial load of food producing animals will require a comprehensive understanding of the epidemiology of these organisms in the host. For organisms such as salmonella many contributing factors have been identified : geography, climate, population density, age of animals, stresses (such as starvation, transport, pregnancy), diet and intestinal flora, contamination of prepared feeds, pasture and drinking water, and survival of the organism outside the host. For recently emerged organisms such as EHECs. much more needs to be known about contributing factors. Controls to limit these human pathogens in production animals include hygiene measures, vaccination, and techniques to clear pathogenic organisms from these animals. The study of E. coli 0157:H7 on-farm is the subject of considerable research in the USA and some of these findings have been referred to earlier.
Foodborne disease surveillance
Most countries record notifiable diseases but few have foodborne disease surveillance programs. Hence caution should be exercised when comparing foodborne disease data from different countries (Arnold and Munce 1997). In Australia notifiable disease data has been collected since 1917. The surveillance and control of communicable diseases is the legislative responsibility of the States and Territories and as such there is lack of uniformity. For example campylobacter infection is not notifiable in NSW but it is in other States. In addition some causes of foodborne disease are not notifiable making it impossible to assess the true incidence of foodborne disease in Australia. The National Notifiable Diseases Surveillance System (NNDSS) was established in 1991 to monitor the occurrence of notifiable diseases and risk factors. The NNDSS data is published in the Communicable Disease Intelligence (CDI). As a result of disparities in reporting in different States, in 1995 the National Health and Medical Research Council (NH&MRC) established a foodborne Disease Working Party. They reported deficiencies in Australia's current surveillance system for foodborne disease and recommended improvements and a need for uniformity between States in surveillance. They concluded that such a recording system coupled with adequate capacity to insestigate outbreaks and conduct applied research is essential to understanding the epidemiology of foodborne disease in Australia (Crerar et al. 1996). Professional liaison between veterinarians, physicians and other important partners along the food chain, including industry and consumer organisations, should be further developed to coordinate the collection and analysis of epidemiological data relating to animals and humans. This needs to be complemented by international collaboration in the surveillance of human foodborne infections.
Outbreaks of human foodborne illness require careful epidemiological investigation to determine the source and highlight possible intervention points for prevention and control programs. The methods used in the investigation of foodborne disease outbreaks are comprehensively discussed by Arnold and Munce (1997). These include methods such as cohort studies, case-control studies and plotting epidemic curves. For example, to make sense of individual faecal isolation of potential enteric pathogens, controls are needed to be sure that isolation independently increases the risk of disease. In animal studies identifying pathogens, the virulence of the isolated organisms in humans needs to he determined because some isolates may not cause disease.
Food Safety advantages of Australian livestock produce in a world market
Australia's livestock produce has some significant advantages compared to that of the Northern hemisphere partly as a result of its geographical isolation but also because of the diligence of our forebears in realising the importance of quarantine and eradication campaigns and pasteurisation of all milk and cheese products. These advantages include :- the absence of "Mad Cow Disease", scrapie in sheep, brucellosis and tuberculosis in cattle, an apparent lower prevalence of E. coli 0157:H7, and no (?) Salmonella typhimurium DT 104 with multiple antibiotic resistance. For how long?
Current and future research
There are gaps in our knowledge of the foodborne pathogens. Further investigation should enhance this knowledge and provide information on how we might intervene to control these pathogens both in the production animal and from contaminating meat. Research is currently underway and further work required into :-
The Meat Industry Strategic Plan (1996) highlighted food safety as a high priority area for the Australian meat industry. The explicit industry goal is to have all enterprises from producer to retailer, operate in accordance with accredited quality assurance systems based on HACCP principles. In response to the industry plan, the Meat Research Corporation established the Food Safety Key Program to study food safety at all levels of red meat production. NSW Agriculture are currently investigating "Pathogens in domestic meat animals - on farm" as part of this Key program. The newly structured Meat and Livestock Australia (MLA) also recognises the importance of food safety and will continue research in this area.
Ensuring food safety in the beef industry requires vigilance, good science, industry involvement and good workable policy.