Introduction
Many people consider the food supply in the USA to be among the safest in the world, and that it is as safe, or safer, now than it has ever been. However, in this country foodborne infections cause an estimated 6.5 million cases and 9,000 deaths annually, with costs of medical treatment and lost productivity estimated to be $24 million.1 Incidents such as the JackintheBox outbreak, which resulted in deaths of children after eating undercooked hamburger, have increased concern among consumers with regard to the safety of their food, particularly animal products. Here and overseas there have been several other foodborne disease "scares", ("mad cow disease" in the UK, Salmonella enteritidis in poultry, Listeria in soft cheeses) that, with the help of the media, achieved a high profile in the consciousness of the consumers. These episodes have the potential to markedly affect consumer behavior, at least in the short term.
How safe is pork? Compared with past ages, when perceptions of the health risk of eating pork led to its exclusion from the diets of a good proportion of the earth's population, the modern age pork industry stands up fairly well. Of all food borne disease outbreaks in the US that can be traced to a particular source, only about 7% involve pork. Does that mean our industry is in relatively good shape, or have we just been lucky that the media has not turned the heat in our direction. Ironically, old perceptions about "worms" in pork die hard, and may take some credit for the reasonable track record of pork. Most foodborne diseases are prevented by adequate cooking, and the reluctance of consumers to eat undercooked pork has undoubtedly contributed to reducing the risk of food borne disease. Another factor may be the failure of pork to get win its share of the fast food market, given that an increased incidence of some foodborne diseases may be linked to changes in eating habits, such as fast food and partially prepared foods.1
The discussion of foodborne disease turns fuzzy when one tries to understand where it is in the food production chain that the hazards lie, and delegate responsibilities appropriately. As mentioned above, proper food storage, handling and preparation would avoid the bulk of foodborne disease. One could argue that education of consumers in these matters should be the most efficient way to reduce foodborne disease. However, in our "consumerisright" world, prevailing opinion seems to be that these bugs should not be in the meat to begin with, and the finger is being pointed beyond the retailers and packers to the producers. The term "preharvest food safety" has been coined to describe attempts to ensure safety of the final product by minimizing or eliminating potential human pathogens and chemical residues from farm animals. The Pork Quality Assurance program is an excellent initiative of the NPPC to address the problem of antimicrobial residues in pork. In this paper, I will concentrate on foodborne organisms most likely to cause problems in our industry.
Who are the Bad Guys?
The long list of strange names in Table 1 shows that there are many players in the game. While some of these can cause disease in pigs, most often they will be present in a herd without causing problems. If these bugs are to be controlled or eliminated at the farm level, some questions that need to be answered include:
| Disease in people | Disease in pigs | Occurrence in pigs | Importance of pig | Importance of other sources | Site in pig | |
|---|---|---|---|---|---|---|
| Salmonella | ||||||
| Yersinia | ||||||
| Toxoplasm | ||||||
| Trichinella | ||||||
| Campylobacter | ||||||
| Listeria | ||||||
| E. coli O157/H7 | ||||||
| Taenia solium |
Unfortunately, information to help answer these questions is scarce. Much of the available information comes from experimental disease or field studies under conditions that differ from those of the industry today. Certainly, changes such as segregated early weaning, multiple site and allin/allout production have the potential to change the picture for these bugs as they do for some of the common production diseases of pigs.
Where to Now?
What can and should the pork industry due to address the issue of preharvest food safety? As usual the bottom line comes down to competition. At home the poultry and beef industries, driven primarily by their more troubled histories, are promoting research into controlling the occurrence of food borne pathogens at the farm level. Abroad, the Scandinavian swine industries, particularly the Danes, have invested heavily in research directed at reducing Salmonella in pork. Interestingly, it appears that they have found more than one way to skin the cat! In a recent study comparing levels of Salmonella in pigs and pork (F. Bager, personal communication), different pictures emerged in different countries. In Holland, Salmonellae were common in both pigs and pork. In Denmark, they were common in pigs, but not in pork. In Sweden, they were rare in both pigs and pork. The interpretation of this is: 1) the Dutch have not focused on control of Salmonella; 2) the Danes lead the world in slaughter technology and through good hygiene prevent contamination of product; and 3) the Swedes have focused on "prefarm" food safety, specifically feedmill hygiene and health of breeding stock. It appears that the Danes may monitor Salmonella in pork, and use this information in quality assurance to their export clients.
So we see our domestic and international competition is concentrating research into control of foodborne pathogens at the farm level. While arguably not the most efficient way to reduce foodborne disease, "preharvest" food safety has shown some promise. The National Pork Producers Council also recognizes the need for research in this area, and has funded several projects in the USA looking at preharvest food safety issues in pork. We are conducting one of these studies in North Carolina to examine the effect of production systems on the occurrence of Salmonella and Toxoplasma in market hogs.
Take-Home Message
Consumer perception is a fragile thing, and perceived safety is one of the major issues that will determine the market share of the meat industries, individually and collectively. There is a strong political push to reduce the risk of foodborne disease at the farm level, but information about how to do it is lacking. As consumers, we all need to be aware of potential hazards in food, and make sure that we store, handle and cook food appropriately.
Suggested Reading
1. Cross HR (1994). Food Safety Reform. Southeast Swine Practitioners' Conference, May 2124, Raleigh. North Carolina Cooperative Extension Service.
