Factors that contribute to foodborne illness
Diagnostic techniques are constantly improving, which allows for identification of diseases, foodborne and otherwise, that would have been of unknown origin in the past. But even considering these facts, public health officials believe that the risk of foodborne illness has increased over the past 20 years.
Changes in demographics, consumer lifestyles and demands, and food production and economics
are changing how food is produced and eaten. In addition, the microbial world is evolving.
The proportion of the population at serious risk of foodborne illness is increasing with the aging of the population and the growing number of people with weakened immune systems. Susceptibility to foodborne pathogens varies within the population. Thus, two people could eat the exact same food and amount; one may become ill while the other does not. People who are at higher risk of becoming seriously ill include infants, young children, the elderly, pregnant women, those taking certain medications and those with diseases such as AIDS, cancer, and diabetes that weaken their immune systems.
Demographers predict that the proportion of people over 60 years old in industrialized countries get affected more. Nursing home residents are particularly susceptible to foodborne illness as the weakening of the immune system that comes with age, and the use of antibiotics and other drugs give pathogens a chance to take hold. Foodborne illnesses are more likely to be fatal in a nursing home than in the general population.
While anybody can get sick from eating contaminated food, the length of time it takes before they become ill and how ill they become depends on a number of factors. Most important among these are age, amount of contamination consumed, and health status of the individual. The body has a number of defenses to protect itself against harmful bacteria. The acidic gastric juices of the stomach are one of the first defenses against foodborne pathogens, as many bacteria cannot survive in an acidic environment.
Very young infants and aging adults produce less, or less acidic, gastric juices than younger, healthy adults. The normal bacteria present in the gastrointestinal system form another protective barrier against foodborne illness by preventing harmful bacteria from colonizing the gut. Thus antibiotics, which do not discriminate between good and bad bacteria, but rather destroy them all, can also increase a person’s susceptibility to foodborne illness. Without the protective bacteria that are normally present in the gastrointestinal tract, pathogenic bacteria can more easily invade and cause illness. Finally, the human immune system, not fully developed at birth, gradually reaches maturity in puberty and then slowly begins to decline after about 50 years of age.
Consumer Lifestyles and Demand
The pace of life has quickened. We often eat meals on the run, since we do not have time to prepare food at home. This means that by the time you eat your food, whether it is a restaurant meal or convenience food, it may have been transported, cooked, cooled, stored, transported again, reheated, and touched by numerous individuals. Each processing step introduces new hazards that could allow for the survival and growth of pathogenic bacteria that ultimately lead to foodborne illness.
Each time you eat food out you are placing your trust in that food establishment and its workers to handle your food properly. Add to this the abuse that occurs after a consumer purchases food and takes it home, and the likelihood of illness increases. Approximately 20 percent of reported
foodborne illness cases occur from food cooked at home.
Young cooks are receiving less training in food preparation than previous generations. This has grave implications for the future of food safety.
Older adults practiced safe behaviors more often than did younger adults.
Consumers are increasingly demanding fresh and natural products, and products with fewer preservatives. Without the traditional preservatives and processing methods that prevent microbial growth, modern all-natural and fresh products are more perishable.
Food processing, mainly canning, freezing, and pasteurizing, not only extend the shelf life of foods, but also inhibit bacterial growth, making food safer.
While pasteurization will kill harmful bacteria, advocates of fresh juice argue that pasteurization diminishes taste. To inform consumers of the risk posed by fresh, unprocessed juices, FDA revised its food labeling regulations. Fruit and vegetable juice products that have not been processed to prevent, reduce, or eliminate pathogenic microorganisms that may be present must have a warning statement to that effect on the label.
As the role of fresh fruits and vegetables in a nutritious diet has become evident, people are including them in their diet more. An increase in the number of foodborne illness outbreaks associated with fresh produce has accompanied this increase in consumption.
Food Production and Economics
In the past, outbreaks of foodborne illness were relatively small and local. Illness could be traced back to local events such as weddings, church dinners, and other gatherings where a large number of people ate the same food. Most of the victims lived in the same area and knew each other. That picture has changed today for several reasons.
Today’s food is produced in vastly different ways from even several decades ago. Food used to be grown, produced, and distributed on a local basis. Food production is now centralized and on a larger scale than in the past. Products made in a single processing plant in mass quantities are shipped all over the country, sometimes the world. A mistake made in the processing will be felt nationwide instead of just locally.
Even the manner in which farmers raise animals can contribute to an increase in food safety problems. A large number of animals are often crowded together, which increases their stress levels and weakens their immune systems. This crowding also facilitates the spread of disease from one animal to another. In the past a sick animal was fairly isolated and would not pass on illness to the rest of the flock or herd. But with animal-to-animal contact, disease can quickly spread.
Many pathogens that cause foodborne illness in humans are present in the animals e consume. However, the pathogens do not cause illness in the animals themselves, making it difficult to distinguish which animals are carrying pathogens and which are not. Cattle infected with E. coli O157:H7 appear just as healthy as those that are not. Little is known on how these animals become infected and how they transmit these pathogens. Research into food safety is expanding to investigate what animals eat and drink and how that ultimately affects humans.
New and Evolving Pathogens
As recently as 50 years ago scientists had identified four foodborne pathogens. Today five times that number are on the list. Twenty years ago scientists did not even recognize three of the four pathogens that is considered the most important in causing foodborne illness—Campylobacter
jejuni, Listeria monocytogenes, and E. coli O157:H7. It is likely that scientists will discover
new foodborne pathogens as laboratory techniques improve.
As living organisms, pathogens are constantly evolving. With better ability to trace outbreaks, scientists are discovering that some bacteria survive in environments previously thought safe. For example, E. coli O157:H7, originally called hamburger disease because of its presence in undercooked ground beef, has shown up in food as diverse as salami, apple cider, raw milk, and lettuce. It also survives in lower pH conditions than originally thought, which leads to outbreaks in acidic foods such as salami and apple cider. It is now known that Yersinia enterocolitica and Listeria monocytogenes can survive and multiply at refrigeration temperatures.
Some foods long considered safe recently have been implicated in foodborne outbreaks. For years scientists believed the inside of an egg was sterile and that Salmonella enteritidis was not of concern. They discovered that chickens infected with Salmonella pass this infection along in their eggs, so that the bacteria can be inside the raw egg, making it unsafe to eat raw or undercooked eggs. Knowledge of this fact caused food safety experts to advise people to cook eggs thoroughly
or to use liquid pasteurized eggs. This means icings, egg drinks, ice cream, cookie dough, sauces, or salad dressings that contain raw eggs could be infected with the bacteria.
Bacteria have evolved to thwart attempts to eliminate them. Some pathogens are now becoming resistant to common antimicrobial agents. It is thought that the resistance may be due to the use of these antibiotics in animals. We are seeing this same adaptability in foodborne bacteria. Salmonella typhimurium DT104 is widely distributed in wild and farm animals, and is resistant to several common antibiotics. There has been a parallel increase of people getting sick from this type of drug-resistant Salmonella.