Bureau of Epidemiology
Bureau of Epidemiology February 2000 Utah Department of Health

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An Action Plan to Eliminate Salmonella enteritidis Illness Due to Eggs

The President’s Council on Food Safety has identified egg safety as one component of food safety that warrants immediate federal interagency action. The “Egg Safety From Production to Consumption: An Action Plan to Eliminate Salmonella enteritidis Illnesses Due to Eggs” was introduced in December 1999. The plan identified the systems and practices to be implemented to reduce and ultimately, eliminate eggs as a source of human S. enteritidis (SE) illnesses. An interim goal of the Egg Safety Action Plan is a 50 percent reduction in egg-associated SE illnesses by 2005.

In support of this plan, Health and Human Services Secretary, Donna E. Shalala, stated, “This ambitious plan is a bold step that will dramatically improve the safety of eggs. Working with the state, industry and consumers, we can achieve our public health goal to eventually eliminate Salmonella illness from eggs”. In addition, Agriculture Secretary, Dan Glickman, said this Administration has made food safety a national priority and has requested substantial funding increases each year for crucial investments in improving food safety, including a nationwide early warning system for foodborne illness, increased inspections and expanded research and consumer education.

Americans consume an average of 234 eggs per person per year. Although only an estimated 1 in 20,000 eggs in the U.S. contain SE bacteria, this rate of contamination means that nearly 3.36 million eggs are infected annually, which exposes a large number of people to SE. Because eggs can become contaminated internally from the hen, common egg-handling practices designed to prevent contamination once the shell is broken are now considered to be inadequate.

CDC surveillance data show that the rate of isolation of SE from infected humans increased throughout the U.S. during 1976-1994 from 0.5 to 3.9 per 100,000 population. Evaluation of regional trends shows a decrease in the SE isolation rate in the Northeast, where egg quality assurance efforts are the most intensive. In contrast, the rate increased approximately threefold in the Pacific region.

A typical case of salmonellosis is characterized by diarrhea, abdominal cramps, nausea, vomiting, fever, and headache. Symptoms usually begin within 6 to 72 hours after consuming food, last 4 to 7 days, and resolve without antibiotic treatment. The benefits associated with preventing human salmonellosis are: (1) the economic benefits of reducing loss of productivity associated with human illness, (2) reduced pain and suffering, and (3) reduced expenditures on medical treatment. The costs associated with human salmonellosis due to SE are estimated to range from $150 million to $870 million annually.

Under the new plan, egg producers and processors will implement one of two strategies to improve egg safety:

Strategy I requires rigorous on-farm agricultural and sanitation practices, extensive testing for SE, and diversion of eggs to pasteurization or cooked product based on positive SE testing.

    Strategy II requires implementation of new technologies to kill the potentially dangerous organism, such as in shell pasteurization, at the packer stage of production.

Both strategies should improve the safety of shell eggs and processed egg products.

The plan also provides a strategy to consolidate egg safety oversight. The Department of Health and Human Services’ Food and Drug Administration (FDA) and the Department of Agriculture’s Food Safety and Inspection Service (FSIS) share federal regulatory responsibility for egg safety. The SE risk assessment model for shell eggs and egg products, developed jointly by the FSIS and the FDA in 1998, predicted that using multiple interventions could achieve a more substantial reduction in SE illnesses than using any one intervention alone. This finding suggests that a broadly based policy is likely to be more effective in eliminating egg-associated SE illnesses than a policy directed solely at one stage of the egg production-to-consumption continuum. At each stage of the egg production-to-consumption continuum, the plan identified the systems and activities necessary to achieve food safety public health goals. The plan offers industry the flexibility to choose from the two SE reduction strategies, each delivering eggs into distribution and to the consumer at an equivalent level of safety. The strategy selection by egg producers and packer/processors determines the point at which the pathogen reduction steps are taken.

For the distribution and retail stages, the plan specified the safe handling practices necessary to ensure consumers receive a safe food product. The plan also describes the surveillance, research, and education activities that must also be conducted to achieve the elimination of egg-associated SE illnesses. To consolidate egg safety oversight responsibilities and provide clarity, the President’s Council on Food Safety identified one responsible agency for each stage of the farm-to-table continuum, based on the strengths of each agency. These follow:

First, FDA develops standards for the producer and the States provide inspection and enforcement on the farm.

Second, FSIS develops standards for both shell egg packers and egg product processors and provides inspection and enforcement for both.

Third, FDA and CDC conduct surveillance and monitoring activities. CDC focuses on human health and FDA on the food supply.

The performance measures that will be used to assess the progress of the plan are the numbers of SE cases, isolates, and outbreaks annually. The data will be collected using the following existing systems: (1) Foodborne Diseases Active Surveillance Network (FoodNet), (2) National Salmonella Surveillance System (via PHLIS), and (3) National SE Outbreak Surveillance System and Foodborne Diseases Outbreak Surveillance System.

The egg safety action plan is available on the web at www.foodsafety.gov/ under “President’s Council on Food Safety”.

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Salmonella enteritidis in Utah, 1999

The incidence of Salmonella in Utah has increased each year, with the exception of 1997. The lull in 1997 followed a large Salmonella enteritidis (SE) outbreak that occurred in 1996. In addition, in four of the last five years, S. enteritidis has accounted for almost 50% of the Salmonella cases reported in Utah (Table 1).

Table 1: Incidence of Salmonella and SE in Utah, 1994—1999

Year

Salmonella Incidence per 100,000

SE as a % of all Salmonella cases

SE Incidence per 100,000

1999*

26.50

59%

15.64

1998

16.90

56%

9.30

1997

13.23

42%

5.60

1996

26.22

59%

14.84

1995

14.30

44%

6.23

1994

10.54

22%

2.30

The number of sporadic cases of SE is continuing to increase in Utah, but single-point outbreaks are primarily responsible for the alarming rates of disease now seen. Salmonella outbreaks are usually traced to foods such as processed meat products, inadequately cooked poultry and poultry products, uncooked or lightly cooked foods containing eggs and egg products, raw milk and dairy products, and foods contaminated with feces by an infected food handler. Epidemics may also be traced to foods that have been processed or prepared with previously contaminated utensils, or on work surfaces contaminated in previous use. SE contamination of chickens and eggs has resulted in many human infections. The consumption of these contaminated products is responsible for the majority of cases of SE in the U.S. Inadequate temperature of food during preparation and cross-contamination during food handling are the most important risk factors resulting in infection.

In 1999, 121 of the 374 (32%) cases of Salmonella enteritidis were associated with single-point outbreaks. Of those 121 cases, 64 were involved with an outbreak in June in which homemade ice cream made with raw eggs was served at a company party. Forty-three cases were related to an outbreak in December in an elementary school setting. An additional eight cases were associated with small parties where homemade ice cream was served. Five others were associated with an outbreak where undercooked eggs were served in a jail setting, and one case in a Utah resident was associated with an outbreak in a California college. The significant increases in June and December are the result of single-point outbreaks (Figure 1).

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Various risk factors have been associated with the increase in sporadic cases of Salmonella enteritidis. Of the 253 sporadic SE cases, 21 reported eating eggs that could have been raw or undercooked. Twenty-five reported eating poultry or cold cuts. Fourteen consumed raw milk or raw milk products. Sixteen reported drinking untreated water. Table 2 summarizes some of the risk factors associated with Salmonella enteritidis.

Table 2: SE Risk Factors, Utah, 1999

RISK FACTOR

# of Sporadic SE Cases With This Risk Factor

% of All Sporadic SE Cases with This Risk Factor

Undercooked/Raw eggs

21

8.3%

Raw Milk/Milk Products

14

5.5%

Poultry/ Cold Cuts

25

9.8%

Travel Outside U.S.

10

3.9%

Untreated Water

16

6.3%

TOTAL

86

33.9%

A limitation of our risk assessment is that it is difficult for people to remember what they ate prior to their onset of symptoms. Many patients listed restaurants and grocery stores where they had purchased food. There did not appear to be any patterns where cases were linked to particular stores or eating establishments. Many people had contact with pets but most listed low risk animals such as cats and dogs. Raw or undercooked eggs, poultry and meat appear to be the most common risk factors for SE in Utah in 1999 (Table 3).

Table 3: Causes of SE in Utah, 1999
Likely Cause of SE Cases

# of SE Cases

% of SE Cases

Outbreak Associated

121

32.3%

Reported Food Risk Factor

86

22.9%

Other or Unknown

167

44.8%

Total Cases

374

Rapid identification and follow-up investigation of cases would help to reduce the number of cases. In addition, prompt environmental investigation of implicated commercial food establishments is necessary. There should be no delay in obtaining environmental and food samples in the event they are needed to complement the patient cultures.

The following recommendations should be followed for all commercial food preparation to prevent infection with Salmonella enteritidis.

  • Commercial food establishments should be advised to use pasteurized eggs rather than shell eggs for recipes that require pooled eggs or raw eggs as stated in the Utah Food Service Sanitation Rule R392-100-3-302.13.

  • Practices conducive to cross-contamination in commercial kitchens should be eliminated.

  • The State and Local Health Departments need an early warning system to promptly detect outbreaks of foodborne illness.

  • Tracebacks of eggs implicated in SE outbreaks in Utah should be carried out to the level of individual farms. Epidemiologic findings should be confirmed by cultures of farms that supplied eggs to the commercial establishment, using the farm-culturing protocols developed by the USDA. Prompt identification of contaminated farms would permit the rapid introduction of appropriate control measures for dealing with infected flocks. Investigations into the mechanisms by which SE was introduced into a farm would be valuable in developing preventive measures for other farms.

  • Addressing egg-related SE in Utah will require cooperation from state and local public health agencies, agriculture officials, and the poultry industry, as stated in the President’s Council on Food Safety Action Plan to Eliminate Salmonella enteritidis Illnesses due to Eggs.

To prevent infection with SE at home, consumers should follow these rules:

  • Don't eat raw eggs. This includes so-called "health-food" beverages made with raw eggs, and foods traditionally made with raw eggs, such as Caesar salad dressing, hollandaise sauce, homemade mayonnaise, ice cream, eggnog, and cookie dough, unless the dish was made with a pasteurized liquid egg product or pasteurized in-shell eggs. Egg mixtures made with an egg-milk base that are cooked to an internal temperature of 160 degrees Fahrenheit (71 degrees Celsius) are safe, too. Use a thermometer to make sure the mixtures reach the correct temperature.

  • Buy eggs only if sold in the grocer's refrigerated case. Open the carton and check that the eggs are clean and uncracked. Store eggs in their carton in the coldest part of the refrigerator, not in the door, and use within three to five weeks after purchase. The refrigerator should be set at 40F (5C) or slightly below. Keep hard-cooked eggs, including dyed Easter eggs, in the refrigerator, not at room temperature. Use within one week. Eggs should not be frozen in their shells. To freeze whole eggs, beat yolks and whites together. Egg whites can be frozen by themselves. Use frozen eggs within one year.

  • Wash hands, utensils, equipment, and work areas with warm, soapy water before and after contact with eggs and egg-rich foods.

  • Don't leave cooked eggs out of the refrigerator for more than two hours. When baking or cooking, take out the eggs you need, and then return the carton to the refrigerator.

  • Cook eggs until yolks are firm.

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Utah Department of Health, Bureau of Epidemiology
Monthly Morbidity Summary - February 2000 - Provisional Data

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The Epidemiology Newsletter is published monthly by the Utah Department of Health, Division of Epidemiology and Laboratory Services, Bureau of Epidemiology, to disseminate epidemiologic information to the health care professional and the general public.

Send comments to:  The Bureau of Epidemiology, Box 142104, Salt Lake City, UT 84114-2104 or call (801) 538-6191

Approval 8000008:  Appropriation 3705

Rod Betit, Executive Director, Utah Department of Health
Charles Brokopp, Dr.P.H., Division of Epidemiology and Laboratory Services
Craig R Nichols, MPA, Editor, State Epidemiologist, Director Bureau of Epidemiology
Gerrie Dowdle, MSPH, Managing Editor
Connie Dean, Production Assistant

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