Transcript Epidemiology of Foodborne Disease

Epidemiology of Foodborne
Disease
ENVR 421
Mark D. Sobsey
Foodborne Disease Outbreaks
1998-2002
• For majority of outbreaks food was eaten outside
the home
• Restaurants were the most commonly reported
place where food was eaten.
• Many outbreaks caused by Salmonella or
norovirus occurred at a school or nursing home.
• For outbreaks caused by ciguatoxin and L.
monocytogenes, food was more commonly
reported to have been eaten at a private home
FBDOs 1998-2002, Cont’d.
• Notable outbreaks were caused by ground beef contaminated with E.
coli O157:H7 and fresh produce contaminated with Salmonella, E.
coli O157:H7, Cyclospora cayetanensis, or hepatitis A
• Multidrug-resistant strains of Salmonella caused outbreaks linked to
unpasteurized milk and ground beef.
• A large multistate outbreak of listeriosis caused by contaminated deli
meat led to one of the largest food recalls in the United States.
• Scombrotoxin (fish-derived histaminic agent) caused the majority of
outbreaks attributable to a chemical etiology.
– Majority of outbreaks associated with tuna,
– Some from with nonscombroidae fish, including 10 by escolar
• Unexpected vehicles of transmission: dry cereal, parsley and
mangoes
FBDOs, 1998-2002, Cont’d.
• Norovirus caused 657 (30%) of the 2,167 FBDOs with
a known etiology and 39% of all outbreak-related
cases in these outbreaks.
• S. Enteritidis: most frequent bacterial cause of FBDOs
– Caused 204 outbreaks
– Accounted for 9% of OBs for which etiology was
determined
– Eggs caused more S. Enteritidis OB than any other food
• L. monocytogenes resulted in 38 outbreak-related
deaths among 256 cases,
– more deaths, and a higher case-fatality rate (15%)
than any other pathogen
Foodborne Disease in The USA: 1993-1997
• Bacterial pathogens caused most outbreaks/infections with
a known etiology
• But, 68% of reported FBDOs were of unknown etiology
– Need improved epidemiologic and lab investigations.
– ~ 50% had incubations period of >15 hours, suggesting
viral etiology. Viruses (e.g., Norwalk-like viruses) are likey
a much more important cause of foodborne disease
outbreaks than is currently recognized.
– Local and state public health lack resources and expertise
to diagnose viral pathogens, but the methods are now
increasingly available in some state laboratories.
– Viral outbreaks are more likely to detected in the future.
Foodborne Disease in the Home
• About half of all Salmonella cases result from
unsafe handling of food in the home.
• Foodborne illness costs the United States $23
billion annually.
• Foodborne illness is often mistaken for “the flu,
as many of the symptoms are similar:
– stomach pain, diarrhea, nausea, chills, fever, and
headache.
• Many experts believe the kitchen is home to
more potentially dangerous bacteria than even
the bathroom.
Foodborne Disease in The USA: 1993-1997
FBDOs with a known etiology:
• multistate outbreaks caused by contaminated produce and
outbreaks caused by E. coli O157:H7 remained prominent.
• S. enteritidis remains a major cause of illness and death.
– ~40% of persons who died from S. enteritidis were residents
of nursing homes.
– Seriousness of S. enteritidis in elderly persons, many of
whom might be immunocompromised.
– Decrease risks for egg-associated infections of S. enteritidis
by not eating raw or undercooked eggs.
– Nursing homes, hospitals, and commercial kitchens should
use pasteurized egg products for all recipes requiring pooled
or lightly cooked eggs. Proper egg storage in homes.
• Several outbreaks involved imported food items, emphasizes the
role of food production and distribution in FBDOs.
Foodborne Disease Burden in the Unites States
• Estimated 76 million illnesses and 5,000
deaths each year.
• Foodborne diseases are common, but only a
fraction of these illnesses are routinely
reported to CDC
– Passive surveillance system
– Many diseases not reportable
– a complex chain of events must occur to report a
foodborne infection to CDC
– Most household foodborne infection are not
recognized or reported
Salmonella Infection
• Causes an estimated 1.4 million foodborne
illnesses/year
• From 1993-1997, only 189,304 Salmonella infections
(~38,00/year) reported through the National
Salmonella Surveillance System
– a passive, laboratory-based system.
• In the same period, 357 recognized outbreaks of
Salmonella infection resulting in 32,610 illnesses
were reported through the Foodborne-Disease
Outbreak Surveillance System.
• These system greatly underestimate the burden of
foodborne disease.
Active Surveillance Network for Foodborne
Disease in the United States: FoodNet
• Foodborne disease component of the CDC's Emerging
Infections Program (EIP).
• Established in 1995
• Collaborative project among CDC, several EIP sites (states
cities and territories), U.S. Department of Agriculture
(USDA), and the U.S. Food and Drug Administration (FDA).
• Consists of active surveillance for foodborne diseases and
• related epidemiologic studies designed to help public health
officials better understand the epidemiology of foodborne
diseases in the United States.
FoodNet Surveillance Sites
FoodNet
Surveillance States:
California, Colorado,
Connecticut, Georgia,
Maryland, Minnesota,
New Mexico, New
York, Oregon,
Tennessee
• Principal foodborne disease component of CDC's Emerging
Infections Program (EIP).
• Collaborative project of CDC, 10 EIP sites, U.S. Department of
Agriculture (USDA), and Food and Drug Administration (FDA)
• Consists of active surveillance for foodborne diseases and related
epidemiologic studies designed to help public health officials better
understand foodborne disease epidemiology in the USA
FoodNet Program
Tracks foodborne illness
using:
• surveys of physicians
and laboratories,
• case-control studies
• active case finding of
targeted pathogens
FoodNet Website:
http://www.cdc.gov/foodnet/default.htm
Targeted Pathogens:
Bacteria:
• Campylobacter
• E. coli O157
• Listeria
• Salmonella
• Shigella
• Vibrio
• Yersinia
Parasites:
• Cryptosporidium
• Cyclospora
Goals of FoodNet
• Describe the epidemiology of new and
emerging bacterial, parasitic, and viral
foodborne pathogens
• Estimate the frequency and severity of
foodborne diseases that occur.
• Determine how much foodborne illness
results from eating specific foods, such as
meat, poultry, eggs produce, etc.
Components of FoodNet
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Active laboratory-based surveillance
Survey of clinical laboratories
Survey of physicians
Survey of the population
Epidemiologic Studies
Water- and Foodborne Illness Surveillance
in Other Countries
• Efforts vary from country to country
• Most have little if any surveillance
• Some have more active and integrated
surveillance than in the United States
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National health care systems
Integrated laboratories
Subsidized laboratory analyses
Other incentives
• political, social, etc.
Laboratory Reports of Gastrointestinal Infections in
England and Wales
Overview of Communicable Diseases
England and Wales - Priorities