What can we do to prevent Shiga toxin-producing E. coli (STEC) infection?
No vaccine is available for E. coli infection, nor are any medications recommended for prevention; taking antibiotics can adversely affect the intestinal microbiota and increase susceptibility to gut infections. However, there are certain things that can be done to reduce risk.
Preventing Infection from Food
Since beef products, especially ground beef, are common sources of STEC, they should always be cooked to the recommended temperatures.
Ground beef should be cooked to an internal temperature of 160oF. Always use a meat thermometer to check the temperature, because color is not a reliable indicator of doneness. That said, it is a good idea not to eat a burger if it appears pink or red on the inside, unless the temperature has been verified to reach 160oF.
Beef products should also be handled carefully to avoid cross contaminating foods that will not be cooked prior to consumption (e.g., fresh fruits and vegetables, burger buns, etc.). Great care should be taken to wash (with hot soapy water) utensils, surfaces, and hands that have contacted raw beef or its juices, before those utensils, surfaces, or hands touch food items that subsequently will not be cooked. One cutting board should be used for fresh produce or other foods that will not be cooked before they are eaten, and another for raw meat. Separate plates and utensils should be used for cooked and raw foods.
In your shopping cart, raw meat should be separated from other foods and placed in plastic bags, if available. At home, raw meat should be placed in containers or sealed plastic bags.
Avoiding consumption of raw milk will reduce the risk of infection with STEC and many other pathogens, as there is no way to consistently prevent fecal contamination from the cows or goats being milked. Similarly, unpasteurized apple cider or juice is another risky food item, which has caused multiple outbreaks. Flour is an emerging cause of STEC outbreaks; it is a raw agricultural product that is not intended to be consumed raw. Therefore, it is best to avoid the temptation to taste batter or dough before baking.
Sprouts are also a frequent cause of outbreaks due to STEC and several other pathogens. Children, older adults, pregnant women, and people with weakened immune systems (such as transplant patients and individuals with HIV/AIDS, cancer, and diabetes) should avoid eating raw or lightly cooked sprouts of any kind (including onion, alfalfa, clover, radish, and mung bean sprouts). If others want to eat sprouts, washing them thoroughly under running water may reduce bacteria but it will not eliminate them. Cooking sprouts thoroughly is the only to kill harmful bacteria for sure.
For other fresh produce, rinse fruits and vegetables under running water without soap, bleach, or commercial produce washes. Do not wash meat, poultry, eggs, or bagged produce marked “pre-washed.”
Wash your hands often, especially before, during, and after preparing food, after handling raw meat, before eating, after using the toilet, and after changing diapers or cleaning up a child who has used the toilet.
Preventing Infection from Water
Water is also a fairly common source of STEC infections. Never drink untreated surface water (for example, from a lake or stream). If the source of your drinking water is a well, have the well tested regularly to make sure it is not susceptible to fecal contamination. When swimming in treated or untreated bodies of water, take care not to swallow water and try not to get water in your mouth. When considering whether to swim in a lake or stream, it is best to avoid doing so if ruminant animals are nearby, such that the body of water is susceptible to contamination from the animals.
Preventing Infection from Animal Contact
Contact with ruminant animals at public venues like petting zoos, agricultural fairs, and educational camps, as well as private farms, is a common source of infection with STEC, especially in children. Outbreaks at these types of venues occur commonly, frequently resulting in HUS and, occasionally, in fatal infection among affected children. National guidelines for venue operators and the public exist and are update periodically (http://www.nasphv.org/Document...).
When visiting this type of venue, ask the operator if they have adhered to all of the national guidelines. Children less than 5 years of age should not have direct contact with young calves or with goats. Food, beverages, toys, pacifiers, spill-proof cups, baby bottles, strollers, or similar items should not be brought into animal areas. Children should be supervised at all times to discourage hand-to-mouth activities (e.g., thumb sucking), contact with manure, and contact with soiled bedding. Hands should be washed immediately upon exit of the animal area and before any hand-to-mouth activity or eating is done. In addition, practice proper hand hygiene after any contact with shoes or clothing that might have come in contact with animals, their waste, or their bedding, as these items can be contaminated during the visit and serve as a mechanism to carry the contamination home with you.
Preventing Infection from Other People
Once people are infected with STEC through the means described above, it can be passed very easily from person-to-person, especially when young children are involved. Children should not attend daycare or preschool with diarrhea. Local and state public health agencies can have different rules, but in general, children (and providers) who have laboratory-confirmed infection with E. coli O157:H7 or a non-O157 STEC that produces Shiga toxin 2 should not go back to daycare or preschool until they have two consecutive negative tests for the bacteria.
The bacteria are still passed in children’s stool for an average of almost three weeks, and sometimes for months, after illness begins, even if symptoms are no longer present. Similarly, these children should not share baths, kiddie pools, or other water venues with other children until they test negative. Caregivers of infected children need to practice meticulous hygiene to avoid infecting themselves or others in the household.
Because soap and water may not be readily available in at-risk areas, travelers should consider taking hand sanitizer that contains ≥60% alcohol. During E. coli outbreaks, clinicians should alert people traveling to affected areas and should be cognizant of possible infections among returning travelers.
What is our government doing to protect us from Shiga toxin-producing E. coli (STEC)?
Food safety regulation is primarily the responsibility of two federal agencies: the United States Department of Agriculture Food Safety and Inspection Service (USDA FSIS) and the United States Food and Drug Administration (FDA).
The USDA FSIS is responsible for ensuring that the nation’s commercial supply of meat, poultry and processed egg products is safe, wholesome, and correctly labeled and packaged (https://www.fsis.usda.gov/wps/...). It has jurisdiction (sometimes shared with states) over more than 6,000 slaughter and further processing establishments, and has inspectors in each plant every day. The primary statute under which USDA FSIS operates is the Federal Meat Inspection Act.
FDA regulates all other foods, including important STEC vehicles such as leafy greens, sprouts, and dairy products. The primary statutes under which it operates are the Federal Food, Drug, and Cosmetic Act, and the Food Safety Modernization Act (FSMA). FSMA, passed in 2011, represents the most sweeping reform of food safety laws in the United States in more than 70 years and is focused on preventing contamination of the nation’s food supply (https://www.fda.gov/food/guida...).
The Centers for Disease Control and Prevention (CDC), part of the United States Department of Health and Human Services (DHHS), is not a regulatory agency. Rather, its food safety mission is accomplished through coordinating national surveillance and outbreak response, and to a large degree, financially supporting state public health to conduct these activities (https://www.cdc.gov/foodsafety...). CDC hosts the Foodborne Diseases Active Surveillance Network (FoodNet), which estimates the number of foodborne illnesses occurring in the United States, monitors trends in incidence of specific foodborne illnesses over time to see how well food safety regulations and policies are working, and determines what proportion of illness due to specific pathogens comes from specific foods and settings (https://www.cdc.gov/foodnet/in...).
Outbreak investigations identify the food source and remove it from commerce, thus preventing additional illnesses from that specific outbreak (https://www.cdc.gov/ncezid/dfw...). But, importantly, identification of specific food vehicles for outbreaks, as well as the reasons they became contaminated, results in changes in food safety regulations and policies, and industry-implemented interventions, to try to prevent similar outbreaks in the future. For example, as a result of the 1993 Jack in the Box E. coli O157:H7 outbreak, USDA designated E. coli O157:H7 an adulterant (1994), required systematic application of Hazard Analysis and Critical Control Point (PR/HACCP) Systems (1996), began requiring microbial testing for E. coli O157:H7 in beef slaughter plants (1996), and implemented many other controls in subsequent years. Outbreaks also prompted the passage of FSMA, and the provisions being implemented through that Act are focused largely on the safety of produce items such as leafy greens, currently a leading cause of outbreaks caused by STEC.