What are foodborne illnesses?
Foodborne illnesses are infections or irritations of the
gastrointestinal (GI) tract caused by food or beverages that contain harmful
bacteria, parasites, viruses, or chemicals. The GI tract is a series of hollow
organs joined in a long, twisting tube from the mouth to the anus. Common
symptoms of foodborne illnesses include vomiting, diarrhea, abdominal pain,
fever, and chills.
Most foodborne illnesses are acute,
meaning they happen suddenly and last a short time, and most people recover on
their own without treatment. Rarely, foodborne illnesses may lead to more
serious complications.
What causes foodborne illnesses?
The majority of foodborne illnesses are caused
by harmful bacteria and viruses.2 Some parasites and chemicals
also cause foodborne illnesses.
Bacteria
Bacteria are tiny organisms that can cause
infections of the GI tract. Not all bacteria are harmful to humans.
Some harmful bacteria may already be present
in foods when they are purchased. Raw foods including meat, poultry, fish and
shellfish, eggs, unpasteurized milk and dairy products, and fresh produce often
contain bacteria that cause foodborne illnesses. Bacteria can contaminate food—making
it harmful to eat—at any time during growth, harvesting or slaughter,
processing, storage, and shipping.
Foods may also be contaminated with bacteria
during food preparation in a restaurant or home kitchen. If food preparers do
not thoroughly wash their hands, kitchen utensils, cutting boards, and other
kitchen surfaces that come into contact with raw foods, cross-contamination—the
spread of bacteria from contaminated food to uncontaminated food—may occur.
If hot food is not kept hot enough or cold food
is not kept cold enough, bacteria may multiply. Bacteria multiply quickly when
the temperature of food is between 40 and 140 degrees. Cold food should be kept
below 40 degrees and hot food should be kept above 140 degrees. Bacteria
multiply more slowly when food is refrigerated, and freezing food can further
slow or even stop the spread of bacteria. However, bacteria in refrigerated or
frozen foods become active again when food is brought to room temperature.
Thoroughly cooking food kills bacteria.
Many types of bacteria cause foodborne
illnesses. Examples include
·
Salmonella, a bacterium found in
many foods, including raw and undercooked meat, poultry, dairy products, and
seafood. Salmonella may also be present on egg shells and
inside eggs.
·
Campylobacter jejuni (C. jejuni), found
in raw or undercooked chicken and unpasteurized milk.
·
Shigella, a bacterium spread
from person to person. These bacteria are present in the stools of people who
are infected. If people who are infected do not wash their hands thoroughly
after using the bathroom, they can contaminate food that they handle or
prepare. Water contaminated with infected stools can also contaminate produce
in the field.
·
Escherichia coli (E. coli), which
includes several different strains, only a few of which cause illness in
humans. E. coli O157:H7 is the strain that causes the most
severe illness. Common sources of E. coli include raw or
undercooked hamburger, unpasteurized fruit juices and milk, and fresh produce.
·
Listeria monocytogenes (L. monocytogenes), which
has been found in raw and undercooked meats, unpasteurized milk, soft cheeses,
and ready-to-eat deli meats and hot dogs.
·
Vibrio, a bacterium that
may contaminate fish or shellfish.
·
Clostridium botulinum (C. botulinum), a
bacterium that may contaminate improperly canned foods and smoked and salted
fish.
Viruses
Viruses are tiny capsules, much
smaller than bacteria, that contain genetic material. Viruses cause infections
that can lead to sickness. People can pass viruses to each other. Viruses are
present in the stool or vomit of people who are infected. People who are
infected with a virus may contaminate food and drinks, especially if they do
not wash their hands thoroughly after using the bathroom.
Common sources of foodborne viruses
include
·
food prepared by a person infected with a virus
·
shellfish from contaminated water
·
produce irrigated with contaminated water
Common foodborne viruses include
·
norovirus, which causes inflammation of the stomach and
intestines
·
hepatitis A, which causes inflammation of the liver
Parasites
Parasites are tiny organisms that
live inside another organism. In developed countries such as the United States,
parasitic infections are relatively rare.
Cryptosporidium
parvum and Giardia intestinalis are
parasites that are spread through water contaminated with the stools of people
or animals who are infected. Foods that come into contact with contaminated
water during growth or preparation can become contaminated with these parasites.
Food preparers who are infected with these parasites can also contaminate foods
if they do not thoroughly wash their hands after using the bathroom and before
handling food.
Trichinella
spiralis is a type of roundworm parasite. People may be infected
with this parasite by consuming raw or undercooked pork or wild game.
Chemicals
Harmful chemicals that cause illness
may contaminate foods such as
·
fish or shellfish, which may feed on algae that produce toxins,
leading to high concentrations of toxins in their bodies. Some types of fish,
including tuna and mahi mahi, may be contaminated with bacteria that produce
toxins if the fish are not properly refrigerated before they are cooked or
served.
·
certain types of wild mushrooms.
·
unwashed fruits and vegetables that contain high concentrations
of pesticides.
Who gets
foodborne illnesses?
Anyone can get a foodborne illness.
However, some people are more likely to develop foodborne illnesses than others,
including
·
infants and children
·
pregnant women and their fetuses
·
older adults
·
people with weak immune systems
These groups also have a greater
risk of developing severe symptoms or complications of foodborne illnesses.
What are the
symptoms of foodborne illnesses?
Symptoms of foodborne illnesses
depend on the cause. Common symptoms of many foodborne illnesses include
·
vomiting
·
diarrhea or bloody diarrhea
·
abdominal pain
·
fever
·
chills
Symptoms can range from mild to
serious and can last from a few hours to several days.
C. botulinum and
some chemicals affect the nervous system, causing symptoms such as
·
headache
·
tingling or numbness of the skin
·
blurred vision
·
weakness
·
dizziness
·
paralysis
What are the
complications of foodborne illnesses?
Foodborne illnesses may lead to
dehydration, hemolytic uremic syndrome (HUS), and other complications. Acute
foodborne illnesses may also lead to chronic—or long lasting—health problems.
Dehydration
When someone does not drink enough
fluids to replace those that are lost through vomiting and diarrhea,
dehydration can result. When dehydrated, the body lacks enough fluid and
electrolytes—minerals in salts, including sodium, potassium, and chloride—to
function properly. Infants, children, older adults, and people with weak immune
systems have the greatest risk of becoming dehydrated.
Signs of dehydration are
·
excessive thirst
·
infrequent urination
·
dark-colored urine
·
lethargy, dizziness, or faintness
Signs of dehydration in infants and
young children are
·
dry mouth and tongue
·
lack of tears when crying
·
no wet diapers for 3 hours or more
·
high fever
·
unusually cranky or drowsy behavior
·
sunken eyes, cheeks, or soft spot in the skull
Also, when people are dehydrated,
their skin does not flatten back to normal right away after being gently
pinched and released.
Severe dehydration may require
intravenous fluids and hospitalization. Untreated severe dehydration can cause
serious health problems such as organ damage, shock, or coma—a sleeplike state
in which a person is not conscious.
HUS
Hemolytic uremic syndrome is a rare
disease that mostly affects children younger than 10 years of age. HUS develops
when E.
coli bacteria lodged in the digestive tract make toxins that
enter the bloodstream. The toxins start to destroy red blood cells, which help
the blood to clot, and the lining of the blood vessels.
In the United States, E. coli
O157:H7 infection is the most common cause of HUS, but infection
with other strains of E. coli, other bacteria,
and viruses may also cause HUS. A recent study found that about 6 percent of
people with E.
coli O157:H7 infections developed HUS. Children younger than
age 5 have the highest risk, but females and people age 60 and older also have
increased risk.3
Symptoms of E. coli
O157:H7 infection include diarrhea, which may be bloody, and
abdominal pain, often accompanied by nausea, vomiting, and fever. Up to a week
after E.
coli symptoms appear, symptoms of HUS may develop, including
irritability, paleness, and decreased urination. HUS may lead to acute renal
failure, which is a sudden and temporary loss of kidney function. HUS may also
affect other organs and the central nervous system. Most people who develop HUS
recover with treatment. Research shows that in the United States between 2000
and 2006, fewer than 5 percent of people who developed HUS died of the
disorder. Older adults had the highest mortality rate—about one-third of people
age 60 and older who developed HUS died.3
Studies have shown that some
children who recover from HUS develop chronic complications, including kidney
problems, high blood pressure, and diabetes.
Other Complications
Some foodborne illnesses lead to
other serious complications. For example, C. botulinum and certain
chemicals in fish and seafood can paralyze the muscles that control breathing. L.
monocytogenes can cause spontaneous abortion or stillbirth in
pregnant women.
Research suggests that acute
foodborne illnesses may lead to chronic disorders, including
·
reactive arthritis, a type
of joint inflammation that usually affects the knees, ankles, or feet. Some
people develop this disorder following foodborne illnesses caused by certain
bacteria, including C. jejuni and Salmonella.
Reactive arthritis usually lasts fewer than 6 months, but this condition may
recur or become chronic arthritis.4
·
irritable bowel syndrome (IBS), a
disorder of unknown cause that is associated with abdominal pain, bloating, and
diarrhea or constipation or both. Foodborne illnesses caused by bacteria
increase the risk of developing IBS.5
·
Guillain-Barré syndrome, a
disorder characterized by muscle weakness or paralysis that begins in the lower
body and progresses to the upper body. This syndrome may occur after foodborne
illnesses caused by bacteria, most commonly C. jejuni. Most people recover
in 6 to 12 months.6
A recent study found that adults who
had recovered from E. coli O157:H7 infections had increased
risks of high blood pressure, kidney problems, and cardiovascular disease.7
When should
people with foodborne illnesses see a health care provider?
People with any of the following
symptoms should see a health care provider immediately:
·
signs of dehydration
·
prolonged vomiting that prevents keeping liquids down
·
diarrhea for more than 2 days in adults or for more than 24
hours in children
·
severe pain in the abdomen or rectum
·
a fever higher than 101 degrees
·
stools containing blood or pus
·
stools that are black and tarry
·
nervous system symptoms
·
signs of HUS
If a child has a foodborne illness,
parents or guardians should not hesitate to call a health care provider for
advice.
How are
foodborne illnesses diagnosed?
To diagnose foodborne illnesses,
health care providers ask about symptoms, foods and beverages recently
consumed, and medical history. Health care providers will also perform a
physical examination to look for signs of illness.
Diagnostic tests for foodborne
illnesses may include a stool culture, in which a sample of stool is analyzed
in a laboratory to check for signs of infections or diseases. A sample of vomit
or a sample of the suspected food, if available, may also be tested. A health
care provider may perform additional medical tests to rule out diseases and
disorders that cause symptoms similar to the symptoms of foodborne illnesses.
If symptoms of foodborne illnesses
are mild and last only a short time, diagnostic tests are usually not
necessary.
How are
foodborne illnesses treated?
The only treatment needed for most
foodborne illnesses is replacing lost fluids and electrolytes to prevent
dehydration.
Over-the-counter medications such as
loperamide (Imodium) and bismuth subsalicylate (Pepto-Bismol and Kaopectate)
may help stop diarrhea in adults. However, people with bloody diarrhea—a sign
of bacterial or parasitic infection—should not use these medications. If
diarrhea is caused by bacteria or parasites, over-the-counter medications may
prolong the problem. Medications to treat diarrhea in adults can be dangerous
for infants and children and should only be given with a health care provider’s
guidance.
If the specific cause of the
foodborne illness is diagnosed, a health care provider may prescribe
medications, such as antibiotics, to treat the illness.
Hospitalization may be required to
treat lifethreatening symptoms and complications, such as paralysis, severe
dehydration, and HUS.
Eating,
Diet, and Nutrition
The following steps may help relieve
the symptoms of foodborne illnesses and prevent dehydration in adults:
·
drinking plenty of liquids such as fruit juices, sports drinks,
caffeine-free soft drinks, and broths to replace fluids and electrolytes
·
sipping small amounts of clear liquids or sucking on ice chips
if vomiting is still a problem
·
gradually reintroducing food, starting with bland,
easy-to-digest foods such as rice, potatoes, toast or bread, cereal, lean meat,
applesauce, and bananas
·
avoiding fatty foods, sugary foods, dairy products, caffeine,
and alcohol until recovery is complete
Infants and children present special
concerns. Infants and children are likely to become dehydrated more quickly
from diarrhea and vomiting because of their smaller body size. The following
steps may help relieve symptoms and prevent dehydration in infants and children:
·
giving oral rehydration solutions such as Pedialyte, Naturalyte,
Infalyte, and CeraLyte to prevent dehydration
·
giving food as soon as the child is hungry
·
giving infants breast milk or fullstrength formula, as usual,
along with oral rehydration solutions
Older adults and adults with weak
immune systems should also drink oral rehydration solutions to prevent
dehydration.
How are
foodborne illnesses prevented?
Foodborne illnesses can be prevented
by properly storing, cooking, cleaning, and handling foods.
·
Raw and cooked perishable foods—foods that can spoil—should be
refrigerated or frozen promptly. If perishable foods stand at room temperature
for more than 2 hours, they may not be safe to eat. Refrigerators should be set
at 40 degrees or lower and freezers should be set at 0 degrees.
·
Foods should be cooked long enough and at a high enough
temperature to kill the harmful bacteria that cause illnesses. A meat thermometer
should be used to ensure foods are cooked to the appropriate internal
temperature:
o 145 degrees
for roasts, steaks, and chops of beef, veal, pork, and lamb, followed by 3
minutes of rest time after the meat is removed from the heat source
o 160 degrees
for ground beef, veal, pork, and lamb
o 165 degrees
for poultry
·
Cold foods should be kept cold and hot foods should be kept hot.
·
Fruits and vegetables should be washed under running water just
before eating, cutting, or cooking. A produce brush can be used under running
water to clean fruits and vegetables with firm skin.
·
Raw meat, poultry, seafood, and their juices should be kept away
from other foods.
·
People should wash their hands for at least 20 seconds with
warm, soapy water before and after handling raw meat, poultry, fish, shellfish,
produce, or eggs. People should also wash their hands after using the bathroom,
changing diapers, or touching animals.
·
Utensils and surfaces should be washed with hot, soapy water
before and after they are used to prepare food. Diluted bleach—1 teaspoon of
bleach to 1 quart of hot water—can also be used to sanitize utensils and
surfaces.
Traveler’s Diarrhea
People who visit certain foreign
countries are at risk for traveler’s diarrhea, which is caused by eating food
or drinking water contaminated with bacteria, viruses, or parasites. Traveler’s
diarrhea can be a problem for people traveling to developing countries in
Africa, Asia, Latin America, and the Caribbean. Visitors to Canada, most
European countries, Japan, Australia, and New Zealand do not face much risk for
traveler’s diarrhea.
To prevent traveler’s diarrhea,
people traveling from the United States to developing countries should avoid
·
drinking tap water, using tap water to brush their teeth, or
using ice made from tap water
·
drinking unpasteurized milk or milk products
·
eating raw fruits and vegetables, including lettuce and fruit
salads, unless they peel the fruits or vegetables themselves
·
eating raw or rare meat and fish
·
eating meat or shellfish that is not hot when served
·
eating food from street vendors
Travelers can drink bottled water,
bottled soft drinks, and hot drinks such as coffee or tea.
People concerned about traveler’s
diarrhea should talk with a health care provider before traveling. The health
care provider may recommend that travelers bring medication with them in case
they develop diarrhea during their trip. Health care providers may advise some
people—especially people with weakened immune systems—to take antibiotics
before and during a trip to help prevent traveler’s diarrhea. Early treatment
with antibiotics can shorten a bout of traveler’s diarrhea.
Points
to Remember
·
Foodborne illnesses are infections or irritations of the
gastrointestinal (GI) tract caused by food or beverages that contain harmful
bacteria, parasites, viruses, or chemicals.
·
Anyone can get a foodborne illness. However, some people are
more likely to develop foodborne illnesses than others, including infants and
children, pregnant women and their fetuses, older adults, and people with
weakened immune systems.
·
Symptoms of foodborne illnesses depend on the cause. Common
symptoms of many foodborne illnesses include vomiting, diarrhea or bloody
diarrhea, abdominal pain, fever, and chills.
·
Foodborne illnesses may lead to dehydration, hemolytic uremic
syndrome (HUS), and other complications. Acute foodborne illnesses may also
lead to chronic—or long lasting—health problems.
·
The only treatment needed for most foodborne illnesses is
replacing lost fluids and electrolytes to prevent dehydration.
·
Foodborne illnesses can be prevented by properly storing,
cooking, cleaning, and handling foods.