Listeriosis in the United States Benjamin J. Silk, PhD, MPH Staff Epidemiologist Enteric Diseases Epidemiology Branch, CDC Public meeting on the Interagency Retail Listeria monocytogenes Risk Assessment May 22, 2013 National Center for Emerging and Zoonotic Infectious Diseases Division of Foodborne, Waterborne, and Environmental Diseases

Listeria monocytogenes  Found in soil and water  Grows at refrigeration temperatures  Transmitted to people by food  Infection (listeriosis) causes severe disease in vulnerable groups

Higher-risk Groups Higher-risk GroupIllnesses/outcomes Pregnant womenFebrile illness, fetal loss Newborn infantsBloodstream infection, meningitis Persons with immunocompromising conditions Bloodstream infection, meningitis Older adultsBloodstream infection, meningitis

Incidence by Risk Group, 2004–2009 Pregnancy-associated

Scallan E et al, Emerging Infectious Diseases, 2011 PathogenIllnessesDeathsCase-fatality rate Listeria1, % Campylobacter1,300, % Salmonella1,230, % Shiga toxin- producing E. coli O157 96, % Listeriosis is rare, but deadly

U.S. Listeriosis Incidence, Data from sentinel site surveillance (FoodNet since 1996)

Progress in late 20 th Century

Detection of Processed Meats as Source, 1989

U.S. Listeriosis Incidence, Data from sentinel site surveillance (FoodNet since 1996) New regulatory policies and industry efforts begin targeting meat processing

Hot Dog Outbreaks, 1998–2011: A Regulatory Success YearsNo. casesNo. deaths/fetal losses Cartwright E et al, Emerging Infectious Diseases, 2013

Deli Meat Outbreaks, 1998–2011: A Regulatory Success YearsNo. casesNo. deaths/fetal losses Cartwright E et al, Emerging Infectious Diseases, 2013

U.S. Listeriosis Incidence, Data from sentinel site surveillance (FoodNet since 1996) New regulatory policies and industry efforts begin targeting meat processing

Advent of PulseNet, 1998 PFGE patterns National database Participating laboratories

Before PulseNet (20 years) 5 outbreaks (2 multistate) Average 54 cases/outbreak Era of PulseNet (7 years) 13 outbreaks (4 multistate) Average 22 cases/outbreak Advent of PulseNet

New Opportunities in 21 st Century

U.S. Listeriosis Incidence, Data from sentinel site surveillance (FoodNet since 1996) New regulatory policies and industry efforts begin targeting meat processing Lack of progress Healthy People 2020 Goal

 Developed in 2004  Enhanced surveillance for all cases  Nationally-standardized food history interviews  Integration with PulseNet  Expedites identification of common food sources during outbreak investigations Listeria Initiative

Outbreak from Whole Cantaloupe, 2011

Newly Recognized Sources of Listeriosis, from Outbreaks, 1998–2011 Implicated food vehicleYearNo. casesNo. deaths/fetal losses None Taco/nacho salad Tuna salad Sprouts None Pre-cut celery Whole cantaloupe Cartwright E et al, Emerging Infectious Diseases, 2013

Mexican-style Cheese Outbreaks, 1998–2011: A Continuing Problem YearNo. casesNo. deaths/fetal losses Cartwright E et al, Emerging Infectious Diseases, 2013

Incidence by Ethnicity, 2004–2009 Illnesses per 100,000 people

Outbreak from Imported Cheese that Cross-Contaminated Other Cheeses, 2012  Imported, contaminated ricotta salata was outbreak source  Cross-contamination of other cheeses propagated the outbreak  First U.S. listeriosis outbreak associated with cut and repackaged cheeses

Summary  Progress in late 20 th Century Interventions targeted processed hot dogs and deli meats Enhanced outbreak detection  New Opportunities in 21 st Century Identify sources of sporadic cases via continued enhancement of outbreak detection (e.g., Listeria Initiative, whole genome sequencing) Newly recognized raw produce sources Persistent sources, especially Mexican-style cheese Pasteurized and unpasteurized Targeting contamination and cross-contamination in retail settings

Public Health Approach to Prevention Surveillance Epidemiological Investigation Applied Research Prevention Measures

For more information please contact Centers for Disease Control and Prevention 1600 Clifton Road NE, Atlanta, GA Telephone: CDC-INFO ( )/TTY: Visit: | Contact CDC at: CDC-INFO or The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention. National Center for Emerging and Zoonotic Infectious Diseases Division of Foodborne, Waterborne, and Environmental Diseases