# Presentation: 365785

## Foods and conditions associated with outbreaks and sporadic cases of foodborne listeriosis

**Robert V. Tauxe, MD, MPH**
**Division of Foodborne, Bacterial and Mycotic Diseases**
**Centers for Disease Control and Prevention, Atlanta, Georgia**

**Food and Drug Administration, March 28  2008**

***Unpublished data in this presentation is preliminary***

## Listeria monocytogenesCharacteristics of the infection

**Perinatal infections**
**Pregnant woman may have fever, or not have a defined illness**
**Spread to the fetus**
**Sepsis **
**Miscarriage**
**Stillbirth**
**Spread to the newborn baby**
**Meningitis**

## Listeria monocytogenesCharacteristics of the infection

**Non-perinatal infections, compromised host**
**Malignancy**
**Organ transplant**
**Immunosuppressive medications**
**HIV/AIDS**
**Elderly**
**Can produce invasive disease**
**Sepsis**
**Meningitis**
**Encephalitis**

## Listeria monocytogenesCharacteristics of the infection

**Normal host**
**Most often is asymptomatic**
**Can produce diarrheal illness with fever**
**Rarely can lead to invasive disease**
**We track invasive illness**

## Clinical outcomes of 169 cases in the 2000-2003  case-control study of sporadic listeriosis 

**Pregnancy-associated cases**
**28 cases  (17% of total)**
**18 hospitalized**
**7 associated with stillbirth**
**Non pregnancy-associated cases**
**141 cases (83%)**
**108 were immunosuppressed = 64%**
**33 not immunosuppressed = 20% **
**131 hospitalized**
**22 died**
**Overal mortality 17%**

## Tracking listeriosis with public health surveillance

**1985:  Large outbreak in California:  142 cases, 40 fatalities, traced to Mexican style soft cheese, queso fresco**
**1986: Active surveillance began in sentinel locations**
**1996: Expanded to other foodborne infections as FoodNet, with support of USDA and FDA**
**1998:  PulseNet began subtyping isolates**
**2001:  Made nationally notifiable**
**2004: Listeria Initiative**

## Listeria Initiative

- All isolates are fingerprinted in PulseNet
- Encourage states to use a standard case interview form
- Monitoring for clusters
- Immediate analysis of clusters using case-control study design
- Cases: serotype/genotype matched
- Controls: patients with non-matching isolates
- One deli turkey outbreak identified and investigated by this means (2005)

## Incidence of reported cases of listeriosis in the United States, 1986-2006

**Incidence of reported cases of listeriosis in the United States, 1986-2006**

**Hot dog outbreak; **
**PulseNet began subtyping**

**Queso**
** ****fresco**
** ****outbreak**

**Deli meat **
**outbreak**

**Turkey frank case,**
**New regulatory policies,**
**Industry efforts**

- 3.1

## FoodNet sites in 2007

- 45 million (15% of U.S. population)

## Relative rates of laboratory-diagnosed cases of infection with Listeria compared with 1996-1998 baseline period, by year, FoodNet.

- 2.0

- 1.0

- 0.9

- 0.8

- 0.7

- 0.6

- 0.5

- 0.4

**1996-1998**

**1999**

**2000**

**2001**

**2002**

**2003**

**2004**

**2005**

**2006**

**2007**

**Relative rate**

**Relative rates of laboratory-diagnosed cases of infection with *****Listeria *****compared with 1996-1998 baseline period, by year, FoodNet.**

- Compared with 1996-1998 period, *Listeria* decreased 32% in 2006 (95% CI:  16% to 45%)

## Rate of invasive listeriosis infection in different population groups, United States, FoodNet  (1996-2000)

**4 per million persons in general population**
**2 per million among White, non Hispanic**
**2 per million among African-Americans**
**4 per million among Asians**
**2 per million among non-Hispanic**
**7 per million among Hispanics**

## Rate of invasive listeriosis infection in different population groups, United States, FoodNet  (1996-2000)

**Among infants**
**Incidence rate 12 fold higher among Hispanics than among non Hispanics**
**Among women of childbearing age**
**Incidence rate 11 fold higher among Hispanics than among non-Hispanics**

## Dietary exposures identified as risk factors in case-control studies of sporadic listeriosis 

**1986-87 (Schwartz, et al)**
**Uncooked or non-reheated hot dogs or undercooked chicken**
**1988-90 (Schuchat, et al)**
**Soft cheeses and food purchased at a deli**
**2000-03 FoodNet (Varma, et al)**
**Hummus and melons prepared in a commercial establishment**

## PulseNet molecular fingerprinting network

**PulseNet molecular fingerprinting network**

**PFGE**
** ****patterns**

**National database**

**Participating laboratories**

**Notes:**
*These sites were the Pennsylvania State Public Health Laboratory, the PulseNet regional laboratory at the Virginia Department of Health, and at CDC
*Coordinating the laboratory efforts in concert with the epidemiologic study required intense collaboration and communication
*CDC’s National Molecular Subtyping Network for Foodborne Disease Surveillance, PulseNet, compared PFGE patterns of isolates from the participating laboratories
*and with the national E. coli O157 database

## Reported outbreaks of listeriosis,1978-2007*, United States

**Reported outbreaks of***** *****listeriosis,1978-2007*, United States**

**2****Outbreaks of confirmed *****Listeria monocytogenes***** reported to CDC (eFORS)**
*** 2007 data are preliminary**

- PulseNet subtyping begins

## Incidence of reported cases and outbreaks of listeriosis,1978-2007*, United States

**Healthy People 2005 Goal**

- Incidence of reported cases* *and* *outbreaks of* *listeriosis,1978-2007*, United States

**1****Incidence data from active surveillance systems (FoodNet)**
**2****Outbreaks of confirmed *****Listeria monocytogenes***** reported to CDC (eFORS)**
***2007 data are preliminary**

## Outbreaks of Listeria monocytogenes Infections Reported to eFORS, 1998-2007*

| Year | State | Serotype | Ill | Food |
| --- | --- | --- | --- | --- |
| 1998 | ML | 4b | 105 | hot dog |
| 1999 | MN |  | 5 | deli meat |
| 1999 | NY |  | 6 | food not reported  |
| 1999 | NY | 1/2a | 4 | hot dog |
| 1999 | FL |  | 2 | deli meat:  turkey; ham; roast beef |
| 1999 | ML | 1/2a | 11 | pate |
| 2000 | ML | 1/2a | 29 | deli meat, sliced turkey |
| 2000 | NC | 4b | 12 | queso fresco |
| 2001 | CA |  | 28 | sandwich, deli |
| 2002 | ML | 4b | 54 | deli meat, sliced turkey |
| 2003 | NY |  | 3 | food not reported  |
| 2003 | TX | 4b | 12 | queso fresco, unpasteurized |
| 2005 | NY | 4b | 6 | food not reported |
| 2005 | NY | 1/2b | 3 | grilled chicken |
| 2005 | ML | 1/2a | 13 | deli meat, sliced turkey |
| 2005 | TX | 4b | 12 | queso fresco |
| 2006 | OR | 4b | 2 | food not reported |
| 2006 | MN |  | 2 | taco or nacho salad |
| 2006 | OR |  | 3 | cheese |
| 2006 | OH | 3b | 3 | ham |
| 2007 | MA | 4b | 4 | pasteurized milk |

**Sliced meat/deli = 7**
**Cheese = 4**
**Hot dogs =  2**
**Pate = 1**
**Nacho salad = 1**
**Chicken = 1**
**Milk = 1**
**Not reported = 4**

- *2007 data are
-  preliminary

## 108 cases in 24 states, 13 were perinatal 
14 deaths (all adults), 4 miscarriages
Epidemiological investigation implicated eating hot dogs from Plant A

**14 deaths (all adults), 4 miscarriages**
**Epidemiological investigation implicated eating hot dogs from Plant A**

**Multistate listeriosis outbreak,**
**1998-1999**

**Serotype 4b**

- Mead 2006 Epidemiol Infect 134:744-751

## 13 cases in North Carolina
All Hispanic
11 were in pregnant women
5 stillbirths
Epidemiological investigation: queso fresco
purchased from door-to-door vendors
homemade queso fresco made using local raw milk
Strains of serotype 4b, with a single PulseNet pattern, from patients, cheeses, and raw milk 
State banned sale of raw milk, launched education program

**All Hispanic**
**11 were in pregnant women**
**5 stillbirths**
**Epidemiological investigation: queso fresco**
**purchased from door-to-door vendors**
**homemade queso fresco made using local raw milk**
**Strains of serotype 4b, with a single PulseNet pattern, from patients, cheeses, and raw milk **
**State banned sale of raw milk, launched education program**

**Cheese-associated outbreak of listeriosis, North Carolina, 2000-2001**

- MWR 50:560, 2001      MacDonald 2005 CID 40:677-82

## Multi-state outbreak of listeriosis, 2002 

**54 patients in 9 states  **
**42 non-pregnant adults**
**8 deaths, 3 miscarriages/stillbirths**
**Serotype 4b **
**Outbreak was caused by turkey deli meat**
**Post-processing contamination likely**
**USDA-FSIS issued new microbial sampling policy**
**Increased environmental testing **
**Can base recall on testing of food contact surfaces**

- Gottlieb 2006 CID 42:29-36

## Conclusions on food sources from epidemiological data

**For last two decades outbreaks most often caused by:**
**Processed ready-to-eat meats, especially turkey and hot dogs**
**Typically contaminated after initial processing**
**Locus of contamination in the processing plant**
**Fresh soft cheeses made with raw milk**
**Sporadic cases associated with:**
**Unreheated hot dogs, undercooked poultry**
**Foods from a deli, soft cheeses**
**Hummus, sliced melons**
**All are foods that support the growth of *****Listeria***

**Overall incidence has declined from 8 per million to 3.1 per million in the last decade, with little change since 2002**
**We are not below the goal of 2.5 per million **
**Mortality is high:  ~ 20% **
**With PulseNet, ability to detect and investigate *****Listeria***** outbreaks has improved**
**Investigating outbreaks leads to immediate and longer term control measures**
**Targeted efforts to reduce contamination have been followed by declines in incidence of human illness**

**General conclusions from the epidemiological data**

## Thank you

*The findings and conclusions in this presentation are those of the author and do not necessarily represent the views of the Centers for Disease Control and Prevention*

**Notes:**
Thank you very much, and I would be happy to entertain questions.