Bacteria and Foodborne Illness
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Foodborne illness results from eating food contaminated with bacteria (or their toxins) or other pathogens such as parasites or viruses. The illnesses range from upset stomach to more serious symptoms, including diarrhea, fever, vomiting, abdominal cramps, and dehydration. Although most foodborne infections are undiagnosed and unreported, the Centers for Disease Control and Prevention estimates that every year about 76 million people in the United States become ill from pathogens in food. Of these, about 5,000 die.
Causes
Harmful bacteria are the most common causes of foodborne illnesses. Some bacteria may be present on foods when you purchase them. Raw foods are not sterile. Raw meat and poultry may become contaminated during slaughter. Seafood may become contaminated during harvest or through processing. One in 20,000 eggs may be contaminated with Salmonella inside the egg shell. Produce such as lettuce, tomatoes, sprouts, and melons can become contaminated with Salmonella, Shigella, or Escherichia coli (E. coli) O157:H7. Contamination can occur during growing, harvesting, processing, storing, shipping, or final preparation. Sources of contamination are varied; however, these items are grown in the soil and therefore may become contaminated during growth or through processing and distribution. Contamination may also occur during food preparation in the restaurant or in the person's kitchen.
When food is cooked and left out for more than 2 hours at room temperature, bacteria can multiply quickly. Most bacteria grow undetected because they do not produce an "off" odor or change the color or texture of the food. Freezing food slows or stops bacteria's growth but does not destroy the bacteria. The microbes can become reactivated when the food is thawed. Refrigeration may slow the growth of some bacteria, but thorough cooking is needed to destroy the bacteria.
Symptoms
In most cases of foodborne illness, symptoms resemble intestinal flu and may last a few hours or even several days. Symptoms can range from mild to serious and include
Risk Factors
Some people are at greater risk for bacterial infections because of their age or immune status. Young children, pregnant women and their fetuses, the elderly, and people with lowered immunity are at greatest risk.
Complications
Some micro-organisms, such as Listeria monocytogenes and Clostridium botulinum, cause far more serious illness than vomiting or diarrhea. They can cause spontaneous abortion or death.
In some people, especially children, hemolytic uremic syndrome (HUS) can result from infection by a particular strain of bacteria, E. coli O157:H7, and can lead to kidney failure and death. HUS is a rare disorder that affects primarily young children between the ages of 1 and 10 years and is the leading cause of acute renal failure in previously healthy children. The child may become infected after consuming a contaminated food, such as meat (especially undercooked ground beef), unpasteurized apple cider or apple juice, or raw sprouts.
The most common symptoms of infection
are vomiting, abdominal pain, and diarrhea, which may be bloody. In
5 to 10 percent of cases, HUS develops about 2 to 6 days after the onset
of illness. This disease may last from 1 to 15 days and is fatal in
3 to 5 percent of cases. Symptoms of HUS include fever, lethargy, irritability,
and pallor. In about half the cases, the disease progresses until the
kidneys are unable to remove waste products from the blood and excrete
them into the urine (acute renal failure). A decrease in circulating
red blood cells and blood platelets and reduced blood flow to organs
may lead to multiple organ failure. Seizures, heart failure, inflammation
of the pancreas, and diabetes can also result. However, most children
recover completely.
You need to see a doctor right away if you have any of the following
symptoms, with or without gastrointestinal symptoms:
- Signs
of shock, such as weak or rapid pulse; shallow breathing; cold,
clammy, pale skin; shaking or chills; or chest pain.
- Signs
of severe dehydration, such as dry mouth, sticky saliva, decreased
urine output, dizziness, fatigue, sunken eyes, low blood pressure,
or increased heart rate and breathing.
- Confusion
or difficulty reasoning.
Diagnosis
Your doctor may be able to diagnose foodborne illness from a list of what you've recently eaten and results from the proper laboratory tests. Diagnostic tests for foodborne illness should include examination of the feces. A sample of the suspected food, if available, can also be tested for bacteria and their toxins as well as for viruses and parasites.
Treatment
Most cases of foodborne illness are mild and can be treated by increasing fluid intake, either orally or intravenously, to replace lost fluids and electrolytes. In cases with gastrointestinal or neurologic symptoms, people should seek medical attention.
In the most severe situations, such as HUS, the patient may need hospitalization in order to receive supportive nutritional and medical therapy. Maintaining adequate fluid and electrolyte balance and controlling blood pressure are important. Doctors will try to minimize the impact of reduced kidney function. Early dialysis is crucial until the kidneys can function normally again, and blood transfusions may be needed.
Prevention
Most cases of foodborne illness can be prevented through proper cooking or processing of food, which kills bacteria. In addition, because bacteria multiply rapidly between 40°F and 140°F, food must be kept out of this "danger zone."
To prevent harmful bacteria from growing in food, always
- Refrigerate
foods promptly. If you let prepared food stand at room temperature
for more than 2 hours, it may not be safe to eat. Set your refrigerator
at 40°F or lower and your freezer at 0°F.
- Cook
food to the appropriate temperature (145°F for roasts, steaks,
and chops of beef, veal, and lamb; 160°F for pork, ground veal,
and ground beef; 165°F for ground poultry; and 180°F for
whole poultry). Use a thermometer to be sure! Foods are properly
cooked only when they are heated long enough and at a high enough
temperature to kill the harmful bacteria that cause illness.
- Prevent
cross-contamination. Bacteria can spread from one food product to
another throughout the kitchen and can get onto cutting boards,
knives, sponges, and countertops. Keep raw meat, poultry, seafood,
and their juices away from other foods that are ready to eat.
- Handle
food properly. Always wash your hands before touching food and after
using the bathroom, changing diapers, or handling pets, as well
as after handling raw meat, poultry, fish, shellfish, or eggs. Clean
surfaces well before preparing food on them.
- Keep
cold food cold and hot food hot.
- Maintain
hot cooked food at 140°F or higher.
- Reheat
cooked food to at least 165°F.
- Refrigerate
or freeze perishables, prepared food, and leftovers within 2 hours.
- Never
defrost food on the kitchen counter. Use the refrigerator, cold
running water, or the microwave oven.
- Never
let food marinate at room temperature; refrigerate it.
- Divide
large amounts of leftovers into small, shallow containers for quick
cooling in the refrigerator.
- Remove
the stuffing from poultry and other meats immediately and refrigerate
it in a separate container.
- Do
not pack the refrigerator. Cool air must circulate to keep food
safe.
Food Irradiation
Food irradiation is the treatment of food with high energy such as gamma rays, electron beams, or x rays as a means of cold pasteurization, which destroys living bacteria, to control foodborne disease. The United States relies exclusively on the use of gamma rays, which are similar to ultraviolet light and microwaves and pass through the food leaving no residue or "radioactivity." Food irradiation is currently approved for wheat, potatoes, spices, seasonings, pork, poultry, red meats, whole fresh fruits, and dry or dehydrated products. Although irradiation destroys many bacteria, it does not sterilize food. Even if you're using food that has been irradiated by the manufacturer, you must continue to take precautions against foodborne illness, through proper refrigeration and handling, to safeguard against any surviving organisms.
Links to Other Disorders
Scientists suspect that foodborne pathogens are linked to chronic disorders and can even cause permanent tissue or organ destruction. Research suggests that when some people are infected by foodborne pathogens, the activation of their immune system can trigger an inappropriate autoimmune response, which means the immune system attacks the body's own cells. In some people, an autoimmune response leads to a chronic health condition.
Chronic disorders that may be triggered by foodborne pathogens are
- arthritis
- inflammatory
bowel disease
- kidney
failure
- Guillain-Barré
syndrome
- autoimmune
disorders
Further research is needed to explain the link.
Common Sources of Foodborne Illness
Source
of illness: Raw and undercooked meat and poultry
Symptoms: Abdominal pain, diarrhea, nausea, and vomiting
Bacteria: Campylobacter jejuni, E. coli O157:H7, L.
monocytogenes, Salmonella
Source
of illness: Raw (unpasteurized) milk and dairy products, such as
soft cheeses
Symptoms: Nausea and vomiting, fever, abdominal cramps, and diarrhea
Bacteria: L. monocytogenes, Salmonella, Shigella, Staphylococcus
aureus, C. jejuni
Source
of illness: Raw or undercooked eggs. Raw eggs may not be recognized
in some foods such as homemade hollandaise sauce, caesar and other salad
dressings, tiramisu, homemade ice cream, homemade mayonnaise, cookie
dough, and frostings.
Symptoms: Nausea and vomiting, fever, abdominal cramps, and diarrhea
Bacteria: Salmonella enteriditis
Source
of illness: Raw or undercooked shellfish
Symptoms: Chills, fever, and collapse
Bacteria: Vibrio vulnificus, Vibrio parahaemolyticus
Source
of illness: Improperly canned goods, and smoked or salted fish
Symptoms: Double vision, inability to swallow, difficulty speaking,
and inability to breathe (seek medical help right away!)
Bacteria: C. botulinum
Source
of illness: Fresh or minimally processed produce
Symptoms: Diarrhea, nausea, and vomiting
Bacteria: E. coli O157:H7, L. monocytogenes, Salmonella,
Shigella, Yersinia enterocolitica, viruses, and parasites
Points to Remember
- Foodborne
illness results from eating food that is contaminated with bacteria,
viruses, or parasites.
- People
at greater risk for foodborne illness include young children, pregnant
women and their fetuses, the elderly, and people with lowered immunity.
- Symptoms
usually resemble intestinal flu. See a doctor immediately if you
have more serious problems, or if you do not seem to be improving
as you'd expect.
- Treatment
may range from replacement of lost fluids and electrolytes for mild
cases of foodborne illness, to hospitalization for severe conditions
such as hemolytic uremic syndrome.
- You
can prevent foodborne illness by taking the following precautions:
- Wash
your hands with hot, soapy water before preparing food and after
using the bathroom or changing diapers.
- Keep
raw meat, poultry, or seafood and their juices away from ready-to-eat
foods.
- Cook
foods properly and at a high enough temperature to kill harmful
bacteria.
- Refrigerate
foods within 2 hours or less after cooking because cold temperatures
will help keep harmful bacteria from growing and multiplying.
- Clean
surfaces well before using them to prepare foods.
- Wash
your hands with hot, soapy water before preparing food and after
using the bathroom or changing diapers.
For More Information
American
Dietetic Association
120 South Riverside Plaza, Suite 2000
Chicago, IL 60606-6995
Consumer Nutrition Hotline: 1-800-366-1655 or 1-800-877-1600
Internet: www.eatright.org
U.S.
Department of Agriculture
14th & Independence Avenue SW.
Washington, DC 20250
Meat and Poultry Hotline: 1-800-535-4555
Internet: www.usda.gov
U.S.
Department of Health and Human Services
200 Independence Avenue SW.
Washington, DC 20201
Phone: 1-877-696-6775 or (202) 619-0257
Internet: www.os.dhhs.gov
U.S.
Environmental Protection Agency (EPA)
Ariel Rios Building
1200 Pennsylvania Avenue NW.
Washington, DC 20460
Phone: (202) 272-0167
Internet: www.epa.gov
U.S.
Food and Drug Administration
FDA (HFE-88)
5600 Fishers Lane
Rockville, MD 20857-0001
Phone: 1-888-INFO-FDA (463-6332)
Internet: www.fda.gov
Center
for Food Safety & Applied Nutrition
5100 Paint Branch Parkway
College Park, MD 20740-3835
Food Information Line: 1-888-SAFEFOOD (723-3366)
Internet: http://vm.cfsan.fda.gov/list.html
Centers
for Disease Control and Prevention
1600 Clifton Road
Atlanta, GA 30333
Phone: 1-800-311-3435 or (404) 639-3534
Internet: www.cdc.gov
Gateway
to Government Food Safety Information
Internet: www.FoodSafety.gov
Partnership
for Food Safety Education
Internet: www.fightbac.org