What virus is frequently transmitted by food handlers who are careless about hygiene?

KEY TERMS

Clinical trials

Dietary Supplement Health and Education Act

Foodborne diseases

FoodNet

Hazard analysis critical control point (HACCP)

PulseNet

Toxins

Americans are very concerned about the safety of their food. Although Americans used to think of their food supply as the safest in the world, this confidence has been shaken in recent decades by widely publicized outbreaks of illnesses caused by foods ranging from bagged spinach to peanut butter.

Since only the most serious cases of foodborne disease are reported, the extent of the problem is unclear. The Centers for Disease Control and Prevention (CDC) has estimated that 48 million people contract foodborne diseases each year, with 3000 deaths.1 With some 300 million people eating three meals per day, not counting snacks, however, the likelihood of getting sick from eating a single meal is extremely small. Many government agencies—local, state, and federal—are involved with regulating food safety. The challenge is enormous: An analysis published in 1992 estimated that some 6100 meat and poultry plants, more than 50,000 food processing establishments, about 537,000 commercial restaurants, 172,000 institutional food programs, 190,000 retail food stores, and 1 million food vending locations are subject to government inspection, and the numbers have certainly grown.2

The need for government oversight of the food supply, like many other public health measures, arose with the urbanization of the population. City dwellers neither grew their own food nor knew its source and history. Demands for action arose as the public became aware of unhygienic conditions such as those in meatpacking plants—conditions revealed in Upton Sinclair’s 1906 novel, The Jungle. Other widespread practices that outraged the public included adulteration of supposedly pure food with cheaper materials and the use of sometimes toxic additives to improve color and conceal spoilage. The Federal Food and Drugs Act and the Meat Inspection Act, both passed in 1906, established a program to supervise and control the circumstances of manufacture, labeling, and sale of food.3

Because similar abuses occurred in the sale of medicines, the 1906 Act included provisions to control manufacturing, labeling, and sale of drugs. The U.S. Food and Drug Administration (FDA), created to oversee regulation of food and drugs, was later given authority over cosmetics, medical devices, and feed and drugs for pets and farm animals.

Causes of Foodborne Illness

Foodborne diseases are most often caused by contamination of foods with bacteria, viruses, or parasites due to breakdowns in sanitation and/or proper food handling practices. Salmonella bacteria, for example, are common contaminants of poultry, meat, and eggs. Infected hens may transfer the pathogens to the eggs as they are being formed in the ovary. Although the bacteria are killed when the food is thoroughly cooked, people who prefer their meat rare or their egg yolks runny are at risk of salmonellosis, especially if the food has been kept at room temperature long enough for the bacteria to flourish. Caesar salad dressing made with raw eggs and homemade eggnog are particularly risky. The symptoms of salmonellosis, like symptoms of most types of food poisoning, include vomiting, diarrhea, and abdominal pain.

Like Salmonella in poultry and eggs, Escherichia coli 0157:H7 is widespread in beef, probably due to the way livestock are raised and processed. To prevent illness and deaths such as those that occurred in 1993 in Seattle, hamburgers must be cooked more thoroughly than the previous standard required. In addition to its occurrence in ground beef, E. coli 0157:H7 has also turned up in other foods, including salami, raw milk, lettuce, alfalfa sprouts, and unpasteurized apple juice. The bacteria are common in the intestinal tracts of cows and are excreted with their feces. The contaminated juice may have been made from apples that fell onto ground where cows had wandered, and the contaminated lettuce was prepared under unsanitary conditions near a cow pen.4,5 The alfalfa sprouts could have been contaminated by being grown in fields near cattle feed lots and irrigated with water contaminated by manure.6

In fact, fresh produce is responsible for an increasing proportion of foodborne illness. For the period 2002 to 2011, fruits and vegetables caused more cases of illness than beef, poultry, and seafood combined.7 In 2008, the largest foodborne disease outbreak in the previous decade was attributed to Salmonella-contaminated jalapeño and serrano peppers imported from Mexico. Investigators traced infection to two farms, where a pool of water used for irrigation was found to contain the bacteria. The investigation was made especially difficult because few of the interviewed victims recalled eating peppers, which were probably a minor ingredient in dishes that were remembered to contain tomatoes. The outbreak sickened 1442 people and contributed to two deaths in 43 states, the District of Columbia, and Canada.8 In 2011, the deadliest outbreak since 1990 was caused by Listeria-contaminated cantaloupe produced by a Colorado company. Thirty people died of the 148 people sickened in 28 states.7

Fish and shellfish are likely to harbor pathogenic microbes if they are harvested from waters polluted by human sewage. Raw clams and oysters are especially dangerous: Because they grow in shallow coastal waters, which are likely to be polluted, these shellfish may carry cholera and related bacteria, hepatitis A virus, and the common Norwalk virus, all capable of causing disease in humans. Fish used uncooked for Japanese dishes such as sushi and sashimi and South American ceviche may also carry parasites harmful to humans.3

Some bacteria cause illness by way of toxins they produce rather than by simple infection. Thus these contaminants are hazardous even after the food is cooked. The best known—and deadliest—of these are the bacteria that cause botulism. They flourish in the absence of oxygen and are most commonly associated with home-canned vegetables that were inadequately cooked before canning, although a number of botulism outbreaks have been traced to commercially canned foods. Once the toxin is formed, it can be destroyed only by boiling for 15 to 20 minutes, not a common practice with canned foods. Certain fish and shellfish may also contain toxins—for example, ciguatoxin or scombroid poison—produced by bacteria or algae that the fish feed on or that grow on them, thereby poisoning the flesh for human consumption.3

Food may also be contaminated by the actions of food handlers, either if they themselves are infected or if they transfer pathogens from one food to another. For example, a salad might be contaminated with Salmonella if the raw vegetables are chopped on a cutting board that had previously been used to cut up uncooked chicken. A number of other bacterial or viral infections tend to be transferred by infected food handlers to raw or cooked foods, such as salads, hot dogs, and delicatessen takeout items. The famous case of Typhoid Mary illustrates how an infected food handler can spread pathogenic bacteria even when she herself has no symptoms. Hepatitis A virus is also frequently transmitted by food handlers who are careless about hygiene. The disease is most contagious 10 to 14 days before the onset of symptoms.

Government Action to Prevent Foodborne Disease

A variety of federal, state, and local agencies are responsible for protecting the safety of the food supply. Because of patchwork legislation, division of responsibility, and lack of coordination, there are major inconsistencies among different types of food in the way food safety is regulated. Increasingly, it has become clear that the system depends too heavily on detecting and correcting problems after they occur rather than preventing them. As nutritionist Marion Nestle stated in her 2010 book, Safe Food: The Politics of Food Safety, “Today, an inventory of federal food safety activities reveals a system breathtaking in its irrationality.”9(p.55) Some of the shortcomings were remedied by the FDA Food Safety Modernization Act, signed by President Obama in January 2011, though many problems remain.

The FDA and the U.S. Department of Agriculture (USDA) share the primary responsibility for ensuring that foods are safe, wholesome, and properly labeled. The laws governing the actions of the two agencies are highly inconsistent. The USDA is responsible for the safety of meat and poultry, including prepared products that contain more than 2 percent of cooked meat or poultry, as well as for processed eggs. The law requires inspection of all meat- and poultry-processing plants daily and that an inspector must be on site whenever a slaughtering plant is in operation. The plants that the USDA inspects account for about 20 percent of federally regulated foods and 26 percent of foodborne illness outbreaks. Its budget for food safety in 2015 was $1014 million.10

The FDA is responsible for all other foods, including seafood and produce, which amount to about 80 percent of federally regulated foods, accounting for 66.5 percent of reported foodborne illness outbreaks. By 2015, its annual budget for food safety had grown to $914 million, still less than USDA’s.11 Because of budgetary constraints, the FDA can inspect food-processing facilities under its jurisdiction only once every 10 years, on average. This leads to the paradox that a plant making frozen cheese pizza may be inspected (by the FDA) only once every 10 years, while a plant making frozen pepperoni pizza will be inspected (by the USDA) almost every day. The Food Safety Modernization Law put additional responsibilities on the FDA, including expanded inspections and setting standards for the safe growing, harvesting, sorting, packing, and storage of fresh fruits and vegetables. However, in the climate of congressional budget cutting, it is not clear how adequate the FDA’s budget will be for carrying out these tasks.

An increasing proportion of Americans’ food is imported from other countries, especially developing countries, which is a challenge to the food safety system. About 50 percent of fresh fruits, 20 percent of fresh vegetables, and 80 percent of seafood sold in the United States are imported.12 The USDA has the power to bar importing of meat and poultry from countries with inferior food safety systems, a power the FDA lacked for fruits, vegetables, grains, and fish until the passage of the Modernization Act in 2011. It still must rely on port-of-entry inspections, an expensive and ineffective approach, but it now has the authority to deny entry of food from a facility that refuses to permit FDA inspection and it can detain for testing shipments of food that it has reason to believe may be harmful.12

Because they are often eaten raw, fruits and vegetables imported from countries with inadequate safety systems are especially risky, causing, for example, a hepatitis A outbreak from Mexican green onions, the Salmonella outbreak from Mexican peppers, and an outbreak caused by the parasite Cyclospora on Guatemalan raspberries in the 1990s. As one CDC official is quoted as saying, “We used to believe you had to travel overseas to get travelers’ diarrhea. It’s a classic example of emerging infections common in Latin America becoming a problem here.”13

Fish and shellfish cause more outbreaks than any other food category except produce.7 Regulation of the fish industry, which falls mainly under jurisdiction of the FDA, is especially difficult because most fish are caught in the wild by independent fishermen in relatively small boats. Fish may have been exposed to viruses or bacterial toxins in polluted waters, or they may have been contaminated with scombroid toxin due to inadequate cooling on the boat. Currently no techniques are available that would allow inspectors on the docks to test for these problems. Shellfish should, in theory, be easier to regulate because their source can be determined. However, much of the enforcement is left to the states, and some of them are lax about enforcing standards.

Fish also have the potential to be contaminated with nonmicrobial toxins. Research published in 2004 revealed that farmed salmon contained potentially dangerous levels of polychlorinated biphenyls (PCBs), as well as dioxin and several organochlorine pesticides. It turned out that farmed fish were fed a concentrated feed that was tainted with the chemicals. Since the news broke, fish farmers are experimenting with new feeds that will eliminate the PCB problem.3 Another hazard from fish was revealed in 2008, when The New York Times published a report that it had found high levels of mercury in sushi made from tuna in 20 Manhattan stores and restaurants.14 It has long been known that pregnant women and children should limit their consumption of some varieties of canned tuna because they contain mercury, but the levels found in the sushi were significantly higher. Mercury gets into the ocean from industrial sources, especially coal-burning power plants, is absorbed by bacteria, and makes its way up the food chain to larger fish such as tuna. There is controversy about the extent of the risk from farmed salmon or tuna, because the risks must be balanced against the many health benefits of eating fish. The FDA recommends that everyone should eat a variety of fish. Pregnant women, women of childbearing age, and young children should avoid tilefish from the Gulf of Mexico, swordfish, shark, and king mackerel. Canned light tuna is lower in mercury than albacore (white) tuna.15

Because of concerns about seafood, as well as repeated outbreaks caused by meat, including the E. coli outbreak from Jack-in-the-Box hamburgers in 1993, the Clinton administration implemented a new preventive approach to meat and seafood safety; which took effect in December 1997.9 Called HACCP (“hassip”), the new system was developed in the 1960s by food processors in cooperation with the National Aeronautics and Space Administration to ensure that foods prepared for the astronauts were safe. Rather than relying on inspections, which can never be done frequently or thoroughly enough to ensure complete safety, the HACCP system focuses on procedures, putting the responsibility on food businesses to analyze their procedures and requiring government inspectors to verify compliance. The system involves identifying potential sources of contamination and devising ways to avoid them. HACCP—which stands for hazard analysis critical control point—requires an analysis of every step in the process of food production, processing, and preparation, as seen in (BOX 24-1). The purpose is to identify each possible hazard and, for each, one or more “control points,” which are practices and procedures that will eliminate, prevent, or minimize the hazard.9

Box 24-1 HACCP PRINCIPLES

1. Conduct a hazard analysis.

2. Determine the critical control points.

3. Establish critical limits.

4. Establish monitoring procedures.

5. Establish corrective actions.

6. Establish verification procedures.

7. Establish record-keeping and documentation procedures.

Data from U.S. Food and Drug Administration, “HACCP Principles & Application Guidelines,” August 14, 2007. www.fda.gov/Food/GuidanceRegulation/HACCP/ucm2006801.htm#princ, accessed August 9, 2015.

Many companies were already using HACCP, and the FDA and USDA in the late 1990s moved to encourage more reliance on the system. When fully implemented, HACCP is intended to reduce the need for inspections, relying instead on frequent reviews of procedures to make sure the system is being carried out. The USDA now has a mandatory system for meat and poultry, including a requirement that the foods be tested for common pathogens. The FDA implemented HACCP for seafood, making it mandatory in 1999. Raw sprouts, eggs, and fresh juice were added later, but for them, use of the system is voluntary.3,16

The FDA, in addition to its oversight of food production on a national scale, issues recommendations that state and local governments can use to regulate establishments that deal with food, including retail stores, restaurants, and institutions such as schools and nursing homes. These rules emphasize the importance of hand washing by food service workers and restricting sick workers from direct contact with food. They also include strict guidelines concerning the temperatures at which food may be stored, cooked, and kept in heating trays. To prevent bacterial growth, foods should be refrigerated at 40 degrees Fahrenheit or below, or heated thoroughly so that internal temperatures are above 140 degrees. Special rules apply to large pieces such as roast meats and stuffed poultry because their internal temperatures may lag behind the external changes in temperature, allowing pathogens to grow during roasting or after refrigeration.3 Local health departments usually enforce these rules by conducting periodic inspections of stores, restaurants, and institutions, and they are usually authorized by local and state laws to close facilities that are significantly in violation.

One potential solution to the problem of foodborne disease is the use of radiation to kill microbial contaminants in food. The idea of irradiating food frightens many people, and the proposal has aroused great opposition among some consumer groups; yet it leaves no radioactive residue, and more than 40 years of research have shown it to be safe. It is already used for some foods in the United States and is widely used in some other countries. Radiation treatment kills pests in dried herbs, spices, and tea, controls insects in wheat and flour, and kills the parasites that cause trichinosis when undercooked pork is eaten. It has been shown to greatly reduce the contamination of chicken breasts with Salmonella, ground beef with E. coli 0157:H7, and shrimp with cholera bacteria. Because microbial contamination of food is such a common hazard, with potentially deadly consequences, many experts believe that widespread use of irradiation could greatly increase the safety of the food supply. The FDA has approved irradiation of a variety of foods including red meat, poultry, shellfish, fruits and vegetables, seeds, herbs and spices, and eggs.17,18 All foods that have been irradiated are required to be labeled as such. Some experts believe that irradiation should be used routinely for many foods. The CDC has estimated that irradiation of high-risk foods could prevent up to a million cases of bacterial foodborne disease each year in North America.19

A very important component of any food safety program is epidemiologic surveillance and prompt follow-up of any foodborne outbreak to prevent further spread of disease. With a nationwide food distribution network, local public health authorities may not recognize that a number of seemingly isolated cases of an illness might be caused by contamination at a single source. The CDC has a program called PulseNet

Only gold members can continue reading. Log In or Register to continue