Richard H. Linton
Professor of Food Safety at Purdue University
We have just experienced one of the largest food recalls in recent history. A multi-state recall of whole shell eggs has been conducted because of their association with a foodborne disease outbreak from contamination with the Salmonella Enteriditis (SE) bacteria. In mid August, 2010 Wright County Egg and Hillandale Farms voluntarily recalled whole shell eggs from a number of farms. The current result has led to a nationwide recall of over a half a billion shell eggs and about 1500 associated illnesses.
Epidemiologic investigations conducted by public health officials in California, Colorado, and Minnesota identified several restaurants and other eating establishment where multiple people became ill with a specific type of SE. Preliminary information, suggested that shell eggs were the likely source of many of the infections. Soon following, FDA, CDC, and state/local regulatory agencies conducted a traceback investigation and found that many of the restaurants received shells eggs from these farms.
The voluntary recall included shell eggs that were shipped since May 19, 2010 to food wholesalers, distribution centers and foodservice companies in California, Illinois, Missouri, Colorado, Nebraska, Minnesota, Wisconsin and Iowa. The recalled shell eggs were packaged under the following brand names: Lucerne, Albertson, Mountain Dairy, Ralph’s, Boomsma’s, Sunshine, Hillandale, Trafficanda, Farm Fresh, Shoreland, Lund, Dutch Farms and Kemps.
There were some signs of illnesses earlier in 2010. In May 2010, the Centers for Disease Control and Prevention (CDC) identified a 4-fold increase in the number of SE isolates through the PulseNet system. PulseNet is a national network of public health and food regulatory agency laboratories coordinated by CDC. The network consists of state health departments, local health departments, and federal agencies (CDC, USDA, FDA). PulseNet participants perform standardized molecular subtyping (or “fingerprinting”) of foodborne disease-causing bacteria by pulsed-field gel electrophoresis (PFGE). There were approximately 200 SE cases occurring every week during late June and early July. Normally, CDC receives an average of about 50 cases of SE illnesses each week.
FDA is currently conducting an extensive investigation of the conditions of the farms at Wright County Egg and Hillandale Farms. The investigation involves microbial sampling, record review and identification of potential sources of SE contamination, including feed. State and local regulatory agencies are also investigating human Salmonella infections in Arizona, Connecticut, Massachusetts, Maryland, North Carolina, Nevada, Oregon, Pennsylvania, Tennessee and Texas. FDA continues to monitor the recall; including conducting audit checks at retail stores, wholesalers, and distributors to ensure that recalled shell eggs are being removed from the market. FDA has created a comprehensive website that provides frequently updated information about the recall (http://www.fda.gov/Food/NewsEvents/WhatsNewinFood/ucm222684.htm).
A person infected with SE usually has a fever, abdominal cramps, and diarrhea beginning 12 to 72 hours after consuming a contaminated food or beverage. The illness usually lasts 4 to 7 days, and most persons recover without antibiotic treatment. However, in some cases, the infected person can have severe diarrhea, requiring hospitalization. The elderly, infants, and those with impaired immune systems may have more severe symptoms of illness. For these immunocomprimised hosts, the infection may spread from the intestines to the blood stream, and then to other body sites, and can cause death unless the person is treated promptly with antibiotics.
Information from scientists differs, but a good estimate for SE contaminated eggs is about 1 in 10,000 to 1 in 20,000 raw whole shell eggs. So the risk of getting a foodborne illness from eggs is still very low. The eggs can become contaminated “from the outside in” with contact from external fecal contamination from the hen. However, SE contaminated eggs are more commonly contaminated “internally.” SE can infect the ovaries of hens that otherwise appear healthy and the egg becomes contaminated before the shell is formed. When contaminated internally, there are no signs that eggs have been contaminated.
While this recall was large in scope with many public health and economic impacts, it is important to recognize that the incident was isolated to 5 farms where the eggs were obtained. Over the years, regulatory agencies and the egg industry have made many strides to minimize contamination of SE. In retail and foodservice operations, we primarily rely on cold temperatures (cooling and refrigeration) to minimize the growth of SE, and, hot temperatures (cooking) to destroy it. Proper cooking will destroy SE in eggs. However, cross-contamination control, good sanitation, and good hygienic practices are also critical to prevent transmission of the organisms in a retail food establishment setting. There are a few recommended interventions that can be used to reduce the risk of SE infections:
· Eggs should be purchased or received from a distributor refrigerated at 45oF (7oC), or below and then held under refrigeration at 41oF (5oC) or below, thereafter.
· Discard any cracked or dirty eggs that have been received.
· Wash hands and cooking utensils with soap and water after contact with raw eggs.
· Refrigerate unused or leftover egg-containing foods.
· Avoid the consumption of raw eggs. In retail and food service establishments, pasteurized egg products or pasteurized in-shell eggs are recommended in place of pooled eggs or raw or undercooked shell eggs. If used, raw shell eggs should be fully cooked. If shell eggs are served undercooked, a consumer advisory should be posted in accordance with the Food Code.
· In hospitals, nursing homes, adult or childcare facilities, and senior centers, pasteurized egg products or pasteurized in-shell eggs should be used in place of pooled eggs or raw or undercooked eggs.
· Cook eggs to the proper temperature and time. The FDA Food Code states that “raw eggs that are broken out of shell and prepared in response to a consumer’s order and for immediate service, should be cooked to 145oF (63oC) or above for at least 15 seconds.” USDA is recommending cooking a) scrambled eggs until that are firm, not runny, b) fried, poached, boiled, or baked eggs until the white and the yolk are firm, and, c) egg mixtures, such as casseroles until the center of the mixture reaches a minimum temperature of 160oF (71oC). Several research groups are reevaluating the safe cooking temperature for eggs to reduce/eliminate SE. Keep an eye out for new research and information for cooking eggs and egg products.
In July of 2009, the egg safety final rule was announced by FDA. The goal of the new rule is to prevent as much as 79,000 cases of foodborne illness and 30 deaths caused by consumption of eggs contaminated with SE. The regulation requires preventive measures during the production of eggs in poultry houses and requires subsequent refrigeration during storage and transportation. Implementing the preventive measures is expected to reduce the number of SE infections from eggs by nearly 60 percent. Information about the final rule can be found at: http://www.fda.gov/Food/FoodSafety/Product-SpecificInformation/EggSafety/EggSafetyActionPlan/ucm170615.htm.