Foodborne diseases result in over 9.4 million illnesses each year in the U.S. Most
foodborne pathogens generally cause a self-limited gastroenteritis, but thousands
of people are hospitalized each year due to complications, including mortality, from
When two or more cases of similar illnesses occur after ingestion of a common food,
a foodborne disease outbreak has occurred. After local and state health departments
report such outbreaks to the Centers for Disease Control and Prevention (CDC), an
investigation is initiated.
A recent CDC report summarizes the most common pathogens and foods implicated in foodborne
disease outbreaks from 2009-’15.
Approximately 800 foodborne disease outbreaks were reported annually, resulting in
roughly 15,000 illnesses (18% of which resulted in hospitalization) and 20 deaths
each year. Outbreaks were reported in all 50 states, the District of Columbia and
While multiple states were involved in only 3% of outbreaks, multistate outbreaks
were responsible for 34% of hospitalizations and 54% of deaths, suggesting more severe
impact than outbreaks limited to single states. The most common location of food preparation
implicated in outbreaks was sit-down restaurants, comprising 48% of all outbreaks
and 33% of outbreak-related illnesses, followed by catering or banquet facilities
and private homes (14% and 12% of outbreaks, respectively).
Nearly any food category can cause a foodborne disease outbreak (see figure 1). The
single food category most commonly implicated in the outbreaks was fish (17% of outbreaks).
The number of illnesses, hospitalizations and deaths associated with these outbreaks
was low, likely because of disease mechanisms of the pathogens involved.
The majority of outbreaks involving fish were found to be caused by scombroid toxin
(85 outbreaks) or ciguatoxin (72). These toxins are produced by fish, including tuna,
mackerel and skipjack (scombroid) and barracuda, mackerel and snapper (ciguatoxin),
and can cause severe neurologic and gastrointestinal tract symptoms. Because these
toxins are produced in individual fish, the size of outbreaks generally is limited.
However, bacterial pathogens can contaminate and replicate in many food products,
explaining why these outbreaks tend to be much larger.
After fish, the most common food categories implicated in outbreaks included dairy
(typically unpasteurized dairy products) and chicken. The number of illnesses resulting
from foodborne outbreaks was most common among chicken (12% of illnesses), pork (10%)
and seeded vegetables such as tomatoes and peppers (10%). The highest numbers of illnesses
occurred in outbreaks of Salmonella in eggs and seeded vegetables. Outbreak-associated hospitalizations were highest
with Salmonella identified in seeded vegetables and chicken.
Deaths were highest among Listeria monocytogenesoutbreaks from contaminated fruits and dairy products.
A single pathogen, either confirmed or suspected, was identified in 71% of outbreaks.
Of those with identified etiologies, norovirus was responsible for the largest percent
of outbreaks and illnesses (46% and 45%, respectively) (see figure 2). This finding
is consistent with previous reports that have found norovirus to be the leading cause
of foodborne disease outbreaks. However, more severe morbidity occurred in infections
caused by Salmonella and Listeria monocytogenes. Outbreaks due to Salmonella caused the highest percentage of hospitalizations (60%), and Listeria caused 52% of deaths.
One of the most severe outbreaks of Listeria monocytogenes was attributed to cantaloupes in 2011. This outbreak involved 28 states and resulted
in 33 deaths, which correlates to a case-fatality rate of 22%.
Other organisms involved in high numbers of outbreaks include Shiga toxin-producing
Escherichia coli, Campylobacter and Clostridium perfringens. In total, 25 species of bacteria, five species of viruses, four species of parasites
and seven different toxins were identified in the 5,670 outbreaks reported during
the six-year surveillance period.
Foodborne disease outbreaks continue to threaten the U.S. population, despite advances
in food safety and regulation. The high numbers of norovirus outbreaks reinforce the
need to strengthen and enforce workplace hygiene, as these outbreaks often are initiated
and perpetuated by food handlers who contaminate ready-to-eat foods.
Many public health interventions have attempted to prevent foodborne disease outbreaks.
Continued efforts are needed to reduce outbreaks and encourage timely reporting.
What is the most common organism implicated in deaths related to foodborne disease
C. Shiga toxin-producing E. coli
D. Listeria monocytogenes
Answer: Listeria monocytogenes
Dr. Haston is a post-graduate training fellow in pediatric infectious diseases at
Emory University School of Medicine and Children’s Healthcare of Atlanta (CHOA). Dr.
Pickering is adjunct professor of pediatrics at Emory University School of Medicine