Foodborne Diseases
On this page:
Infectious diseases spread through food or
beverages are a common, distressing, and sometimes life-threatening
problem for millions of people in the United States and around the world.
The U.S. Centers for Disease Control and Prevention (CDC) estimates 76
million people suffer foodborne illnesses each year in the United States,
accounting for 325,000 hospitalizations and more than 5,000 deaths.
Foodborne disease is extremely costly. Health experts estimate that the
yearly cost of all foodborne diseases in this country is $5 to $6 billion
in direct medical expenses and lost productivity. Infections with the
bacteria Salmonella alone account for $1 billion yearly in direct
and indirect medical costs.
There are more than 250 known foodborne diseases. Bacteria cause most
cases, followed by viruses and parasites. Natural and manufactured
chemicals in food products also can make people sick. Some diseases are
caused by toxins (poisons) from the disease-causing organism, others by
bodily reactions to the organism itself. People infected with foodborne
germs may have no symptoms or develop symptoms ranging from mild
intestinal discomfort to severe dehydration and bloody diarrhea.
Recently, public health, agriculture, and environmental officials have
expressed growing concern over keeping the nation's food and water supply
safe from terrorist acts. This bioterrorism threat is being studied by a
number of U.S. agencies, including the Food and Drug Administration,
Department of Agriculture, Centers for Disease Control and Prevention,
Environmental Protection Agency, and National Institutes of Health.
This fact sheet will describe five foodborne diseases caused by
bacteria.
- Botulism
- Campylobacteriosis
- E. coli infection
- Salmonellosis
- Shigellosis
Return to top 
Many times, foodborne
diseases are easy to avoid. These are some basic ways to prevent being
infected by most foodborne germs. Specific ways to avoid getting sick from
foodborne organisms are described in the sections on foodborne diseases
- Wash hands carefully before preparing food.
- Wash hands, utensils, and kitchen surfaces with hot soapy water
after they touch raw meat or poultry.
- Cook beef and beef products thoroughly, especially hamburger.
- Cook poultry and eggs thoroughly.
- Eat cooked food promptly and refrigerate leftovers within 2 hours
after cooking.
- Wash fruits and vegetables thoroughly, especially those that will be
eaten raw.
- Drink only pasteurized milk and juices and treated surface water.
- Wash hands carefully after using the bathroom, changing infant
diapers, or cleaning up animal feces.
Return to top
Botulism is a rare but serious illness
caused by botulinum toxin (poison) produced by
Clostridium
botulinum bacteria. This toxin affects the nerves and if untreated,
can cause paralysis and respiratory failure. U.S. health care providers
report an average of 110 cases of food, infant, and wound botulism to CDC
each year. About 10 to 30 outbreaks of foodborne botulism are reported
every year. Although this illness does not occur frequently, it can be
fatal if not treated quickly and properly.
Often, cases of
foodborne botulism come from home-canned foods with low acid content, such
as asparagus, green beans, beets, and corn.
C. botulinum is
anaerobic, which means it can survive and grow with little or no oxygen.
Therefore, it can survive very well in sealed containers. Outbreaks of the
infection, however, are often from more unusual sources such as chili
peppers, tomatoes, and improperly handled baked potatoes wrapped in
aluminum foil.
- Double vision and drooping eyelids
- Slurred speech
- Dry mouth and difficulty swallowing
- Weak muscles
Symptoms of foodborne botulism usually begin within 18 to 36 hours
after eating contaminated food, but can occur in as few as 6 hours or as
much as 10 days afterward.
A health care provider can use
laboratory tests to identify
C. botulinum toxin in the blood or
stool of an infected person.
If diagnosed early,
health care providers can treat foodborne botulism successfully with an
antitoxin that blocks the action of the bacterial toxin circulating in the
blood. Although antitoxin keeps the disease from becoming worse, recovery
still takes many weeks. Sometimes doctors try to remove contaminated food
still in the gut by making the patient vomit or by giving the patient an
enema.
Patients who develop severe botulism experience breathing failure and
paralysis and need to be put on ventilators (breathing machines).
If left
untreated, this illness can cause paralysis of the arms, legs, trunk, and
muscles that help with breathing. The paralysis usually improves slowly
over several weeks.
C. botulinum toxin is one of the most potent toxins known in
nature. Exposure to the toxin, particularly in an aerosolized form, can be
fatal. It has been weaponized by rogue states and is a focus of current
counter-bioterrorism efforts.
- Follow strict hygienic steps when home canning.
- Refrigerate oils with garlic or herbs.
- Keep baked potatoes wrapped in aluminum foil hot until served, or
refrigerate them.
- Consider boiling home-canned food before eating it, to kill any
bacteria which might lurk in the food.
In
1989, the U.S. Food and Drug Administration (FDA) approved Botulinum Toxin
Type A, a protein produced by
C. botulinum, as a treatment for
two eye muscle disorders, and in 2000, to treat cervical dystonia, a
neurological movement disorder causing severe neck and shoulder
contractions. In April 2002, FDA approved this toxin to temporarily
improve the appearance of moderate to severe frown lines between the
eyebrows.
Return to top
Campylobacteriosis is an
infectious disease caused by
Campylobacter bacteria.
Campylobacter jejuni,
C. fetus, and
C. coli are
the types that usually cause campylobacteriosis in people.
C.
jejuni causes most cases of the illness.
According to CDC, C. jejuni is the leading cause of bacterial
diarrheal illness in the United States, affecting an estimated 2.4 million
people every year. The bacteria cause between 5 and 14 percent of all
diarrheal illness worldwide. C. jejuni primarily affects children
under 5 years old and young adults (15-29 years old). Health care
providers report more than 10,000 cases to CDC yearly. In the United
States, few people die from Campylobacter infection.
Humans can get infected
from handling raw poultry, eating undercooked poultry, drinking
nonchlorinated water or raw milk, or handling infected animal or human
feces. Most frequently, poultry and cattle waste are the sources of the
bacteria, but feces from puppies, kittens, and birds also may be
contaminated.
- Diarrhea (often bloody)
- Abdominal cramping and pain
- Nausea and vomiting
- Fever
- Tiredness
Some infected people have no symptoms. Campylobacteriosis usually lasts
for 2 to 5 days, but in some cases as long as 10 days. Rarely, some people
have convulsions with fever or meningitis.
A health care provider can use
laboratory tests to identify
Campylobacter in the stool of an
infected person.
Most people infected with
Campylobacter will get better with no special treatment. If a
person needs treatment, a health care provider can prescribe an antibiotic
such as ciprofloxacin or azithromycin. Erythromycin helps treat diarrhea
caused by
Campylobacter. Those with diarrhea should drink plenty
of water.
Some people infected with
Campylobacter
develop arthritis.
A small number of people with campylobacteriosis may develop
Guillain-Barré Syndrome (GBS), the leading cause of acute paralysis in
this country. This rare condition develops from 2 to 4 weeks after
Campylobacter infection and usually after diarrheal symptoms have
disappeared. People with GBS suffer from increasing paralysis of the limbs
which lasts for several weeks. In more severe cases, they develop
breathing problems requiring very long hospital stays.
- Wash hands before preparing food.
- Wash hands immediately after handling raw poultry or other meat.
- Wash all food preparation surfaces and utensils that have come in
contact with raw meat thoroughly with soap and hot water.
- Cook poultry products to an internal temperature of 170 degrees
Fahrenheit for breast meat and 180 degrees Fahrenheit for thigh meat.
- Drink pasteurized milk and chlorinated or boiled water.
- Wash hands after handling pet feces or visiting zoos and petting
zoos.
Return to top
Certain types of
Escherichia coli bacteria, commonly called
E. coli can
cause foodborne illness. Harmless strains of
E. coli can be found
widely in nature, including the intestinal tracts of humans and
warm-blooded animals. Disease-causing strains, however, are a frequent
cause of both intestinal and urinary-genital tract infections.
Several different strains of harmful E. coli can cause
diarrheal disease. A particularly dangerous type is called
enterohemorrhagic E. coli, or EHEC. EHEC often causes bloody
diarrhea and can lead to kidney failure in children or people with
weakened immune systems.
In 1982, scientists identified the first dangerous strain in the United
States. The type of harmful E. coli most commonly found in this
country is named O157:H7, which refers to chemical compounds found on the
bacterium's surface. This type produces one or more related, powerful
toxins which can severely damage the lining of the intestines.
Other types, including O26:H11 and O111:H8, also have been found in
this country and can cause human disease.
Cattle are the main sources of E. coli O157:H7, but other
domestic and wild mammals also can harbor these bacteria.
E. coli bacteria and
its toxins have been found in
- Undercooked or raw hamburgers
- Salami
- Alfalfa sprouts
- Lettuce
- Unpasteurized milk, apple juice, and apple cider
- Contaminated well water
Unsuspecting swimmers have been infected by accidentally swallowing
unchlorinated or underchlorinated water in swimming pools contaminated by
human feces. People also can get infected by swimming in
sewage-contaminated water.
E. coli toxin can damage the lining of the
intestine and cause other symptoms including
- Nausea
- Severe abdominal cramps
- Watery or very bloody diarrhea
- Tiredness
- Vomiting (occasionally)
Occasionally, people develop low-grade fever or vomiting. Symptoms
usually begin from 2 to 5 days after eating contaminated food and may last
for 8 days.
A health care provider can use
laboratory tests to identify
E. coli in the stool of an infected
person.
Most people
recover from
E. coli infection within 5 to 10 days without
treatment. Antibiotics are usually not helpful, and health care experts
recommend against taking antidiarrheal medicines.
Hemolytic uremic syndrome (HUS), a serious complication
of EHEC, can lead to kidney failure. In North America, HUS is the most
common cause of acute kidney failure in children, who are particularly
prone to this complication. This life-threatening condition is usually
treated in an intensive care unit of a hospital, sometimes with blood
transfusions and kidney dialysis.
- Eat only thoroughly cooked beef and beef products.
- Cook ground beef patties to an internal temperature of 160 degrees
Fahrenheit.
- Avoid unpasteurized juices.
- Drink only pasteurized milk.
- Wash fresh fruits and vegetables thoroughly before eating raw or
cooking.
Enterotoxigenic
E. coli (ETEC), which produce a
toxin similar to Cholera toxin, can cause diarrhea. These strains
typically cause so-called travelers diarrhea because they are prevalent
contaminants in food and water in developing countries.
Enteropathogenic E. coli (EPEC) are associated with persistent
diarrhea (lasting 2 weeks or more) and are more common in developing
countries where they can be transmitted by contaminated water or contact
with infected animals. Health experts do not know how much disease some of
these other types of E. coli cause in the United States.
Return to top
Salmonellosis, or salmonella, is an
infection caused by
Salmonella bacteria.
Salmonella
infections are increasing in the United States. Many types of this
bacteria cause disease in animals and people. While the occurrence of
different types of
Salmonella varies from country to country,
Salmonella typhimurium and
S. enteritidis are the two
most commonly found in the United States.
In 1984, an antibiotic-resistant strain of S. typhimurium,
called Definitive Type 104 (DT104), was first found in the United Kingdom
and recently in the United States. Now it is the second most common strain
(after S. enteritidis) of Salmonella found in humans.
This strain poses a major new threat because it is resistant to several
antibiotics normally used to treat people with Salmonella
infections.
Salmonellosis may occur in small, contained outbreaks in the general
population or in large outbreaks in hospitals, restaurants, or
institutions for children or the elderly. While the disease is found
worldwide, health experts most often report cases in North America and
Europe. Every year, CDC receives reports of 40,000 cases of salmonellosis
in the United States. The agency estimates that 1.4 million people in this
country are infected, however, and that 1,000 people die each year with
salmonellosis. Symptoms are most severe in the elderly, infants, and
people with chronic conditions. People with AIDS are particularly
vulnerable salmonellosis-often suffering from recurring episodes.
Salmonella bacteria can be found in food
products such as raw poultry, eggs, and beef, and sometimes on unwashed
fruit. Food prepared on surfaces that previously contained raw meat or
meat products can, in turn, become contaminated with the bacteria. This is
called cross-contamination.
In the past few years, CDC has received reports of several cases of
salmonellosis from eating raw alfalfa sprouts grown in contaminated soil.
Salmonella infection frequently occurs after handling pets, particularly
reptiles like snakes, turtles, and lizards.
Salmonellosis can become a chronic infection in some people who may not
have symptoms. Though they may have no symptoms, they can spread the
disease by not by not washing their hands before preparing food for
others. In fact, health care experts recommend that people who know they
have salmonellosis not prepare food or pour water for others until a
laboratory tests show they no longer carry Salmonella.
- Diarrhea
- Fever
- Abdominal cramps
- Headache
In most people, symptoms begin from 12 hours to 3 days after being
infected. These symptoms, along with possible nausea, loss of appetite,
and vomiting, usually last for 4 to 7 days. Diarrhea can be severe and
require hospitalization.
A health care provider can use
laboratory tests to identify
Salmonella in the stool of an
infected person.
Most cases of salmonellosis
clear up within 5 to 7 days and don't require treatment. People with
severe diarrhea may need intravenous fluids. If the infection spreads from
the intestines into the bloodstream, health care providers can treat it
with antibiotics such as ampicillin.
While most
people recover successfully from salmonellosis, a few may develop a
chronic condition called Reiter's syndrome. This syndrome can last for
months or years and can lead to arthritis. Its symptoms are
- Painful joints
- Irritated eyes
- Painful urination
Unless treated properly, Salmonella can escape from the
intestine and spread by blood to other organs, sometimes leading to
death.
Typhoid fever, a more serious disease, results from infection with
S. typhi. This disease, which can be fatal if untreated, is not
common in the United States. It is frequently found in developing
countries, usually in contaminated water. It's also a risk in areas where
flooding or earthquakes cause sewer systems to overflow.
Appropriate antibiotics are usually effective for treating typhoid
fever, although the incidence of antibiotic-resistant S. typhi is
increasing is some parts of the world.
- Drink only pasteurized milk.
- Cook poultry and eggs thoroughly.
- Don't eat foods containing raw eggs, such as homemade caesar salad dressing,
cookie dough, and hollandaise sauce or drink homemade eggnog made with raw
eggs.
- Handle raw eggs carefully.
- Keep eggs refrigerated.
- Throw away cracked or dirty eggs.
- Cook eggs thoroughly.
- Cook poultry products to an internal temperature of 170 degrees Fahrenheit
for breast meat and 180 degrees Fahrenheit for thigh meat.
- Wash all food preparation surfaces and utensils that have come in contact
with raw poultry or raw eggs with soap and hot water.
- Wash hands immediately after handling raw poultry or raw eggs.
- Wash hands immediately after handling reptiles or contact with pet feces.
Return to top
Shigellosis, also called bacillary
dysentery, is an infectious disease caused by
Shigella bacteria.
Four main types of
Shigella cause infection:
Shigella
dysenteriae,
S. flexneri,
S. boydii, and
S.
sonnei. CDC estimates that more than 400,000 cases occur every year
in the United States. Health care providers report about 18,000 cases to
CDC each year. Most cases in this country are caused by
S.
sonnei.
People can be infected from foodborne
Shigella by
- Eating food or drinking beverages contaminated by food handlers infected
with Shigella who didn't wash their hands properly after using
the bathroom.
- Eating vegetables grown in fields containing sewage.
- Eating food contaminated by flies which were bred in infected feces.
- Drinking or swimming in contaminated water.
S. sonnei is the most common type of Shigella in
developed countries, including the United States. Outbreaks of shigellosis
frequently occur in tropical or temperate climates, especially in areas
with severe crowding and/or poor hygiene, which sometimes occur in day
care and institutional settings.
Some people have no symptoms but can still pass the bacteria to others.
An extremely low number of organisms (10-100) is needed to transmit
Shigella. Therefore, it is commonly transmitted by food service
workers who are sick or infected, but have no symptoms, and who do not
properly wash their hands after using the toilet. Those who know they have
shigellosis should not prepare food or pour water for others until
laboratory test show they no longer carry Shigella bacteria.
- Fever
- Tiredness
- Watery or bloody diarrhea
- Nausea and vomiting
- Abdominal pain
Symptoms usually begin within 2 days after being exposed to
Shigella. Symptoms usually are gone within 5 to 7 days.
People with mild infections
usually get better quickly, without taking medicine. When treatment is
necessary, health care providers usually prescribe an antibiotic such as
ampicillin or ciprofloxacin. Antidiarrheal medicines may make the illness
worse.
People who
had diarrhea symptoms usually recover completely, although their bowel
habits may not return to normal until several months later.
S.
dysenteriae type 1 produces Shiga toxin and can lead to
life-threatening hemolytic uremic syndrome (HUS), the same complication
that develops in some cases of infection with
E. coli
(enterohemorrhagic
E. coli or EHEC).
S. flexneri infection can progress to Reiter's syndrome which
can last for months or years and can lead to chronic arthritis. Its
symptoms are
- Painful joints
- Irritated eyes
- Painful urination
- Wash hands thoroughly with soap and water before preparing foods and
beverages.
- Wash hands thoroughly after using the bathroom or changing infant
diapers.
- Disinfect diaper-changing areas after use.
- Help young children wash their hands carefully after they use the
bathroom.
- Avoid swallowing swimming pool water.
Return to top
The National Institute of Allergy and
Infectious Diseases (NIAID), is the federal government's lead agency for
conducting and funding research on many infectious diseases. Scientists at
the Institute and NIAID-supported scientists are using basic, clinical,
and applied research to better understand how to detect, treat, and
prevent foodborne diseases.
Basic research is helping scientists to better understand how pathogens
(germs) spread by contaminated food or water cause disease in humans.
NIAID-supported researchers are studying the bacterial genes that help
pathogens establish themselves in the human body and cause disease. For
example, scientists have identified genes that appear to be involved in
signaling certain immune system cells to cause inflammation, and which may
contribute to the development of diarrhea.
Other NIAID-sponsored research focuses on methods by which the organism
grows and interacts in host cells. Scientists have discovered that some
intestinal bacteria recognize when they are in a human host and respond by
activating a particular set of powerful genes that enable the organism to
live in the host and cause disease. Future studies will define new ways to
intervene, whether by prevention or treatment, in the disease process.
NIAID supports several research studies on E. coli 0157:H7
(EHEC).
Researchers have sequenced the genome of E. coli 0157:H7
(EHEC) and compared it with the genome of the harmless E. coli
K12. Seventy percent of the two genomes are identical, and the genome of
E. coli 0157:H7 is about 30 percent larger than K12. As
researchers compare and contrast these and other strains of E.
coli, their ability to answer key questions in evolution and disease
processes will become easier.
Researchers are working to develop and test monoclonal antibodies to
treat EHEC infection, thus preventing hemolytic uremic syndrome (HUS) from
developing. (Scientists use monoclonal antibodies as tools for binding to
specific protein molecules. As such, they are invaluable in research,
medicine, and industry.)
Investigators are further defining the ways by which the toxins
produced by EHEC and Shigella result in the kidney damage leading to HUS.
The primary goal of this research is to better understand how kidney
vascular disease progresses. Researchers are developing antitoxins that
may help prevent HUS from developing in infected children.
Researchers also are exploring vaccines to prevent EHEC and Shigella
infections in animals or people.
NIAID-supported scientists found that children with bloody diarrhea
should not be treated with antibiotics. Antibiotics can lead to the
release of more bacterial toxins and further kidney damage, including
subsequent HUS.
Cholera is a major source of water- and foodborne sickness and death in
the developing countries of Asia, Africa, and South America, particularly
during epidemics and in refugee settings. Scientific studies have shown
that Vibrio cholerae bacteria, which cause cholera, constantly
adapt to changes in the environment.
Individual Cholera bacteria can join together to form large
mats called biofilms. NIAID-supported scientists recently have sequenced
the genome of V. cholerae and have identified a gene family that
allows the bacteria to form biofilms. Biofilms protect the bacteria from
environmental stresses and makes the pathogen more resistant to being
disinfected by chlorine. When conditions become favorable, other genes
allow the bacteria to revert to their original forms. This is one method
V. cholerae uses to survive harsh conditions. Better
understanding of how the pathogen can shift will help researchers develop
new ways to control it during epidemics.
In addition to the genomic studies mentioned above, scientists have
determined the complete genome sequences for Salmonella typhi,
S. typhimurium, and Campylobacter jejuni. Sequencing
studies are underway for Shigella, Yersinia, and other
harmful strains of E. coli. Scientists hope this new information
will speed the discovery of new targets for treatments and vaccines
against foodborne pathogens.
Through preliminary tests of live, attenuated Shigella
flexneri vaccine candidates, scientists have discovered two new
toxins that may contribute to the diarrhea associated with
Shigella species. Studies are under way to find out how these
toxins cause fluid loss. The findings will provide crucial information on
how to improve attenuated vaccines to prevent shigellosis.
The NIAID enteric diseases program also supports basic and clinical
research on other water- and foodborne pathogens including Vibrio
cholerae, Helicobacter pylori, Yersinia,
Listeria, Clostridia, Bacteroides,
Staphylococcus and effects of toxins on the intestinal tract.
NIAID supports an Enteric Pathogens Research Unit to carry out research
on the immune response that takes place in the mucous membrane lining of
the gut. Because foodborne pathogens universally affect this lining, these
studies will give researchers information needed to make vaccines or
develop treatment for diseases these pathogens cause. The research
includes
- conducting clinical trials of vaccine candidates
- using adjuvants, delivery systems, or dosing schedules to help
scientists find out how best to increase the immune response to vaccines
- studying mucosal immunity
In addition to the organisms mentioned above, NIAID conducts research
on gastrointestinal viruses that cause diarrhea such as caliciviruses,
rotavirus, astrovirus, and hepatitis A virus. Scientists at the NIAID
Laboratory of Infectious Diseases in Bethesda, Md., devised the first
method for detecting Norwalk virus (a particular calicivirus) particles
and for measuring Norwalk virus-specific antibodies (disease-fighting
proteins).
Current studies are trying to produce new vaccines including edible
vaccines against Norwalk virus and hepatitis A. NIAID scientists developed
a recently licensed inactivated vaccine for hepatitis A virus
infection.
Return to top
National Institute
of Allergy and Infectious Diseases
U.S. Environmental Protection
Agency
World Health Organization
Return to top
