# Presentation: 101998

## Risk Assessments for Salmonella Enteritidis in Shell Eggs and Salmonella spp. in Liquid Egg Products (Part I)

- October 22, 2004

## Contributors

- Margaret Coleman
- Eric Ebel
- Neal Golden
- Allan Hogue
- Abdel Kadry
- Janell Kause
- Heejeong Latimer
- Harry Marks
- Nathan Quiring
- Wayne Schlosser
- Carl Schroeder

- 04/30/2002

## Peer Reviewers

**Scott Ferson**
*Applied Biomathematics*
*United States of America*
**Tom Humphrey**
*University of Bristol*
*United Kingdom*
**Christine Little**
*Health Protection Agency*
*United Kingdom*
**John Maurer**
*University of Georgia*
*United States of America*
**Maarten Nauta**
*National Institute for Public Health*
* **and the Environment*
*The Netherlands*

- 04/30/2002

## Colleagues from the Risk Assessment Division

- William James
- Uday Dessai
- Terry Disney
- David Goldblatt
- Chuanfa Guo
- Michael Kasnia
- David LaBarre
- Silvia Kreindel
- Heather Quesenberry

- 04/30/2002

## Other Colleagues

- Ken Anderson
- Tristan Cogan
- Victor Cook
- Edmund Crouch
- Philip Derfler
- Daniel Engeljohn
- Richard Gast
- Roger Glasshoff
- Elke Jensen
- Suzanne Hasiak
- Arshad Hussein
- Dolores Hill
- Walt Hill
- Peter Holt

- Karen Hulebak
- Stan Kaplan
- Lynn Larsen
- Priscilla Levine
- Victoria Levine
- Carol Maczka
- Ronald Meekhof
- Celine Nadon
- Alecia Naugle
- Bharat Patel
- Merle Pierson
- Louise Ryan
- Patricia Schwartz
- Amelia Sharar

- 04/30/2002

## Additional thanks to

- FDA, Center for Food Safety and Applied Nutrition
- Provided comments for consideration. Revision ongoing
- Centers for Disease Control and Prevention
- Plans to review

- 04/30/2002

## Outline

- Background
- Microbiology of *Salmonella*
- Epidemiology of Human Salmonellosis
- Conclusion

- 04/30/2002

## Background

## Background

- In 1996, FSIS, in collaboration with FDA, initiated a risk assessment to characterize the public health effects associated with consumption of *S. *Enteritidis-contaminated eggs
- Results indicated multiple interventions along the farm-to-table chain were necessary to reduce significantly the risk of illness from *S. *Enteritidis in eggs
- Results were useful in developing the Egg Safety Action Plan, etc. but were not deemed sufficient for evaluating FSIS risk management options for developing performance standards for eggs

- 04/30/2002

## Background

- Since then, however, additional data have become available
- FSIS has conducted a national baseline survey to measure *Salmonella *levels in liquid egg products produced in the U.S
- Experimental studies have clarified scientific issues associated with SE contamination in egg yolk
- The American Egg Board sponsored studies on lethality kinetics of *Salmonella *spp. in liquid egg products
- A dose-response model for *Salmonella* spp. has been developed by FAO/WHO

- 04/30/2002

## Microbiology of Salmonella

## Nomenclature

*Salmonella *Enteritidis

| Salmonella species and subspecies | No. of Serovars |
| --- | --- |
| S. enterica subsp. enterica (I) |            1,454 |
| S. enterica subsp. salamae (II) |               489 |
| S. enterica subsp. arizonae (IIIa) |                 94 |
| S. enterica subsp. diarizonae (IIIb) |               324 |
| S. enterica subsp. houtenae (IV) |                 70 |
| S. enterica subsp. indica (VI) |                 12 |
| S. bongori (V) |                 20 |
| TOTAL |            2,463 |

- Bailey JS, Maurer JJ. 2001. *Salmonella *species. In: *Food Microbiology: Fundamentals and Frontiers* (Doyle MP, Beuchat LR, Montville TJ, eds.),  pp 141-170. ASM Press, Washington DC.

- 04/30/2002

## The Salmonellae

- Gram-negative, rod-shaped bacteria
- Facultatively anaerobic
- Motile by means of flagella

- 04/30/2002

## Affect of Temperature and pH on Growth of Salmonella 

| Condition | Minimum | Optimum | Maximum |
| --- | --- | --- | --- |
| Temperature (oC)  | 5.2 | 35–43 | 46.2 |
| pH | 3.8 | 7–7.5 | 9.5 |

- 04/30/2002

## Contamination of Shell Eggs

*S. *Enteritidis is transmitted to eggs through two routes
- Trans-ovarian (vertical) transmission
- SE is introduced into the egg from infected ovaries or oviduct tissue before egg is laid
- Primary route of contamination
- Trans-shell (horizontal) transmission
- Can result from fecal contamination of the eggshell

- 04/30/2002

## Epidemiology of Human Salmonellosis

## Salmonellosis

- Foodborne salmonellosis in the U.S.
- ~1.3 million illnesses
- ~15,600 hospitalizations
- ~550 deaths

- Mead PS, Slutsker L, Dietz V, McCaig LF, Bresee JS, Shapiro C, et al. Food-related illness and death in the United States. Emerg Infect Dis 1999 Sep-1999 Oct;5(5):607-25.

- 04/30/2002

**Notes:**
Based on work by colleagues at the CDC, it is estimated that foodborne salmonellae cause approximately 1.3 million illnesses, 15,600 hospitalizations, and 550 deaths per year in the United States. The basis on which these estimated are based may be found in the seminal article “Foodborne Illness and Death in the United States” by Paul Mead and colleagues. You see the full reference here.

## Salmonellosis

- Salmonellosis case costs:
- ~$440 (no physician visit)
- ~$950 (physician visit)
- ~$10,700 (hospitalization)
- ~$455,000 (death)

- http://www.ers.usda.gov/data/foodborneillness/

- 04/30/2002

**Notes:**
The economic costs of salmonellosis have also been estimated.

## Disease Characteristics

- Symptoms include diarrhea, fever, abdominal pain or cramps, vomiting, headache, and nausea
- Incubation period ranges from 8 to 72 hours with symptoms lasting up to a week
- Severity of infection varies. While most are self-limiting, some are fatal

- 04/30/2002

## Sequellae

- Reactive arthritis
- Symptoms develop 7 to 30 days after intestinal illness
- Develops in about 2 to 3% of persons with salmonellosis
- Urethritis
- Conjunctivitis
- Weight loss of over 5 kg
- Oral ulcers
- Pneumonia

- Maki-Ikola O, Granfors K. *Salmonella*-triggered reactive arthritis. Scand J Rheumatol 1992;21(6):265-70.

- 04/30/2002

##  Dose-response and Outbreaks

- FAO/WHO. 2002.  Risk assessments of *Salmonella *in eggs and broiler chickens. Rome: FAO/WHO.

- 04/30/2002

## Salmonella Cases Per 100,000 Population, 2000

*Salmonella* Cases Per 100,000 Population, 2000

- Centers for Disease Control and Prevention. *Salmonella *surveillance: Annual summary, 2000.
- Centers for Disease Control and Prevention.  Morb Mortal Wkly Rep  2001 Apr;50(13):241-6.

- 04/30/2002

**Notes:**
Infection from Salmonella appears to occur most frequently in the summer. Similar seasonal patterns have been documented for outbreaks of infection caused by S. Enteritidis and for Salmonella-positive spent hens at slaughter. Warm temperatures provide an environment in which Salmonella can grow during the processes of production, transport, and storage. The data presented in this figure may also reflect, in part, picnics, cookouts, and other similar group functions that commonly take place in the summer. 

## Incidence of Salmonella Infections by Age Group (Yrs), 2000

- Centers for Disease Control and Prevention. *Salmonella *surveillance: Annual summary, 2000.
- Centers for Disease Control and Prevention.  Morb Mortal Wkly Rep  2001 Apr;50(13):241-6.

- 04/30/2002

## Salmonella Isolates from Human Sources by Serotype and Year, 1976-2000 

- Centers for Disease Control and Prevention. *Salmonella *surveillance: Annual summaries, 1977-2000.

- 04/30/2002

**Notes:**
5,116 S. Enteritidis isolates reported for 2002 (comprising 15% of all Salmonella isolates). Second only to S. Typhimurium (7,062 isolates; 21.9%)

## S. Enteritidis and Eggs

- The period 1976 to 1995 saw an 8-fold increase in infections with *S. *Enteritidis reported to the CDC
- Greater than 75% of the infections were associated with foods containing undercooked eggs

- Angulo FJ, Swerdlow DL. 1999. Epidemiology of human *Salmonella enterica *serovar Enteritidis infections in the United States.  In: *Salmonella enterica *serovar Enteritidis in Humans and Animals (Saeed AM, Gast RK, Potter ME, Wall PG, eds.),  pp33-42. Iowa State University Press, Ames.

- 04/30/2002

## S. Enteritidis and Eggs

- From 1985 through 1998, 794 SE outbreaks were reported to CDC
- Involved 28,644 illnesses, 2,839 hospitalizations, and 79 deaths
- Greater than 75 percent were associated with foods containing undercooked eggs

- Centers for Disease Control and Prevention. *Salmonella *surveillance: Annual summari, 1985-1998. U.S. Department of Health and Human Services. Atlanta.

- 04/30/2002

## Illness Estimates from Surveillance Data

| Surveillance Step | Estimate |
| --- | --- |
| 1. Salmonella illnesses ascertained by FoodNet  |            4,330 |
| 2. Isolates serotyped  |           3,964 |
| 3. Serotyped isolates that were SE  |              585 |
| 4. Ratio of serotyped isolates that were SE  |             0.15 |
| 5. Estimated number of illnesses from Salmonella attributable to SE  |              639 |
| 6. Population of catchment area |   30,500,000 |
| 7. Incidence of SE in catchment area |  2.1/100,000 |
| 8. U.S. population  | 281,400,000 |
| 9. Estimated cases of SE in U.S. |            5,896 |
| 10. Illness underreporting multiplier |                37 |
| 11. Illness from SE |       254,688 |
| 12. Proportion of SE illnesses from eggs |             0.80 |
| 13. Estimated annual illnesses from SE in eggs |       174,356 |

- 04/30/2002

## Conclusions

## Conclusions

- Based on surveillance data, shell eggs have been identified as an important vehicle of infection from *S. *Enteritidis
- >75% of *S. *Enteritidis outbreaks have been egg-associated
- We know of no outbreaks from *Salmonella *in liquid egg products
- New data and modeling techniques have enabled us to conduct robust risk assessments for *S. *Enteritidis in shell eggs and *Salmonella *spp. in liquid egg products

- 04/30/2002

## Slide 30

- 04/30/2002