Food-borne illness

Definition
Food-borne illness is a general term used to describe a variety of symptoms that may occur after eating contaminated food. Although it's often referred to as food poisoning, this label is misleading. The food isn't poisoned -- it's contaminated.
Food can become contaminated with many different things, including bacteria or their toxins, viruses, fungi, parasites, chemical insecticides or harmful metals, such as mercury or lead. The follow- ing information is specific to bacterial contamination, which is responsible for many cases of food-borne illness. Bacteria cause illness by infecting the intestines or producing poisonous toxins. Most cases are mild and short-lived with full recoveries. However, certain strains of bacteria have the potential to cause serious illness or even death.


Causes/associated factors
There are many types of bacteria that cause food-borne illnesses. These illnesses include botulism, campylobacteriosis, E. coli infection, listeriosis, salmonellosis (salmonella), shigellosis (bacillary dysentery), staphylococcal food poisoning and yersiniosis.
Foods such as meat, poultry, seafood, eggs and unpasteurized dairy products can become contaminated with bacteria during growing, harvesting, processing, storing, shipping or final preparation. If the bacteria aren't killed before they're eaten, they can multiply inside your body and cause illness. This is more likely to occur when food is not cooked or reheated adequately, raw contaminated food comes in contact with other foods, food remains uneaten for too long, or refrigerated food is not kept cold enough. (Bacterial growth can occur at 40°F or warmer).

Some foods, such as unpasteurized dairy products and soft cheeses, are more likely to harbor germs. Contaminated water or fish from contaminated waters are other potential sources of bacteria.

People at highest risk for developing food-borne illness and complications of illness include:

infants and young children
seniors
pregnant women and their fetuses
people who have weak immune systems
People who have decreased stomach acidity (such as from gastric surgery or regular use of antacids) are also at increased risk of developing food-borne illnesses.

Severe food-borne illness
Botulism is an uncommon paralytic illness caused by a lethal toxin that's released by the bacterium Clostridium botulinum, which is found naturally in the soil. Food-borne botulism occurs after ingesting foods contaminated with the toxin. Home-canned, low-acid foods, such as green beans or corn, are responsible for most cases of botulism. Less often, illness may develop after eating other foods, such as home-canned or fermented fish, garlic or herbs in oil, chili peppers or baked potatoes wrapped in foil. Botulism can also occur after ingesting the bacteria, which activate and produce the toxin in the intestines. This occurs most often in children under age 1 who've eaten honey. Home-canned fruits and vegetables can also be a source of bacteria.

Infection with the bacterium E. coli O157:H7 can also cause severe illness. The bacteria's toxins damage the intestines, producing bloody diarrhea. In a few children and older adults, the infection destroys red blood cells, causing bleeding, kidney failure and even death. It develops after eating contaminated foods, such as meat (especially ground beef) that is undercooked, unpasteurized milk or juice, or sprouts.


Transmission
The incubation period (time from exposure until symptoms appear) for food-borne illnesses varies depends on the particular bacteria involved and the quantity of bacteria ingested. Sometimes symptoms can appear as quickly as one hour. In other cases, symptoms may take as long as several days to appear.
For example, consider these typical incubation periods:


botulism 18 to 36 hours
campylobacteriosis two to five days
E. coli infection three to four days
listeriosis nine to 48 hours
salmonella one to three days
shigellosis 24 to 48 hours
staphylococcus one to six hours


Signs/symptoms
The onset, duration, severity and number of symptoms depends mainly on the type of bacteria and the amount consumed. Generally, food-borne illness resembles the intestinal or stomach flu, producing symptoms such as:
nausea
vomiting
diarrhea
severe abdominal cramping
fever
Severe diarrhea or vomiting can lead to dehydration, which occurs when you lose more fluid than you're able to take in or replace.

For botulism, symptoms may include double or blurred vision, drooping eyelids, muscle weakness or paralysis, or difficulty speaking, swallowing or breathing.


Diagnosis
Food-borne illness may be suspected when several members of a family suddenly become ill and show the same symptoms after eating the same food or when several people who ate at the same restaurant or picnic become sick. Diagnosis of food-borne illness is usually based on your symptoms. Food or stool samples can be analyzed to identify the presence of bacteria.

Treatment
For most mild cases of food-borne illness, it's best to let nature run its course. Initially, diarrhea and vomiting are nature's way of eliminating the bacteria and toxins from your body. If your symptoms become severe or you're at risk for complications, however, medical intervention may be necessary.
Contact your doctor immediately for severe symptoms such as:

severe, bloody or prolonged diarrhea
prolonged vomiting
symptoms of dehydration, such as decreased urination, dry mouth, extreme thirst, sunken eyes or dizziness when standing
high fever or shaking chills
Fluids and electrolytes lost through vomiting or diarrhea may be replaced orally or with intravenous fluid therapy. Antidiarrheal medications are usually not given because they slow the elimination of bacteria and toxins from the body. In certain cases, your doctor may prescribe an antibiotic. When you return to your normal diet, start with liquids and then move to bland food. Progress slowly to normal foods.


Complications
Food-borne illness may lead to:
hemolytic uremic syndrome (an acute condition causing blood cell destruction, kidney damage and anemia -- a condition marked by a decreased number of red blood cells or hemoglobin, a protein in red blood cells that contains iron)
blood infection
low blood sugar
shock
It's thought that food-borne illnesses may also affect the immune system for some people, resulting in chronic illnesses such as:

arthritis
autoimmune disorders (conditions in which the body produces antibodies to attack its own tissue for no known reason)
inflammatory bowel disease
kidney failure
Guillain-Barré syndrome (a serious central nervous systemcondition that can lead to breathing difficulty, shock and paralysis)
Researchers continue to look for a possible connection between food-borne illness and the development of chronic disease.

In severe cases, food-borne illness may be fatal.


Pregnancy-specific information
During pregnancy, you may be at higher risk for certain food-borne illnesses or complications. Be sure to consult your doctor if you experience symptoms of food-borne illness.
Listeriosis and salmonellosis can become serious during pregnancy. If you're pregnant, you're 20 times more likely to develop listeriosis, and once infected, you're more likely to become seriously ill. The infection can result in miscarriage, stillbirth or serious illness in the baby. Salmonellosis can result in severe symptoms during pregnancy, and it can be passed on to your baby.

To prevent listeriosis, pregnant women should be careful to avoid the following foods:

hot dogs, luncheon meats and deli meats, unless reheated so they're steaming hot (Be careful not to cross-contaminate other foods, utensils or food preparation surfaces with fluid from hot dog packages. Wash your hands after handling these foods.)

soft cheeses not labeled as made with pasteurized milk, such as feta, Brie, Camembert, blue-veined cheeses, Mexican-style cheeses (such as queso blanco, queso fresco, queso de hoja, queso de crema and asadero) and Panela (You may eat hard cheeses, semisoft cheeses such as mozzarella, pasteurized processed cheese slices and spreads, cream cheese and cottage cheese.)

refrigerated pâtés or meat spreads, unless they're canned

refrigerated smoked seafood, such as salmon, trout, whitefish, cod, tuna or mackerel (This type of seafood is most often labeled Nova-style, lox, kippered, smoked or jerky. You may eat smoked seafood that's been canned or cooked in a casserole or other dish.)

Senior-specific information
As you age, your natural defenses against food-borne bacteria diminish. Protective stomach acid secretion decreases and the immune system weakens. You also face a higher risk for complications related to food-borne illness. Be sure to handle food safely (See the "Prevention" section below), and consult your doctor if you have any symptoms of food-borne illness.

Prevention
Contaminated food often has no unusual odor, color or texture. To help prevent the bacterial contamination of food, the National Food Safety Initiative recommends four basic steps:
Clean: Wash your hands and kitchen surfaces often.
Wash your hands for at least 20 seconds with hot soapy water before food preparation and after handling raw meat, fish, seafood, eggs or poultry. Also wash your hands after using the toilet, changing diapers, or handling pets. Wash countertops, cutting boards and utensils with hot, soapy water before and after preparing each food. Wash dishcloths and sponges frequently in hot water or use paper towels.

Separate: Don't cross-contaminate.
Bacteria can spread from one food to another, especially from raw meat, poultry and seafood. Avoid this by keeping these foods away from other foods during shopping, storage and preparation. Use a separate cutting board for meat, poultry and seafood. When you serve cooked food, do not use unwashed dishes or utensils that were used to handle raw foods.

Cook: Cook to proper temperatures.
Cook meat, poultry, fish, shellfish and eggs thoroughly to the proper temperature. Be sure to use a thermometer. Many food packages now contain these cooking directions. Examples of adequate cooking include:

ground red meat 160°F, brown or gray inside, juice runs clear
roast, steaks, chops 145°F, brown or gray inside, juice runs clear
poultry, whole 180°F, juice runs clear
poultry, ground 165°F
eggs Firm, not runny
egg dishes 160°F
fish 160°F, opaque, flakes with a fork


Thoroughly reheat all leftovers. Soups and gravies should come to a boil. Other foods should be heated to 165°F. At this temperature, they will be hot and steaming throughout. If microwaving, be sure no cold spots remain.

Chill: Refrigerate promptly and properly.
Keep perishable foods, such as eggs, meat, fish and dairy products, refrigerated. When transporting them, pack them in an ice chest if it will take you more than an hour to reach a refrigerator.

Refrigerate leftovers immediately after a meal. For rapid cooling, divide large quantities into smaller containers. Most bacteria grow at temperatures between 40 and 140°F, so keep your refrigerator at 40°F or colder. Throw away any foods that remain at room temperature for longer than two hours.

Freeze foods at 0°F or colder. When defrosting frozen foods, place them in the refrigerator for a day or two, microwave them, or put them in cold water.

Never use food that doesn't look or smell right or that may have been stored too long. Remember, however, contaminated food often has no unusual odor, color or texture. If you're in doubt about a food, don't taste it. Throw it away.

Additional recommendations


Avoid nonpasteurized dairy products and soft cheeses, such as Mexican soft cheese, feta, Brie, Camembert and Roquefort, especially if you're at high risk for developing a food-borne illness.

Never feed honey to a child younger than age 1 due to the risk of infant botulism.

Elderly adults, those who have weak immune systems and children under 5 should not eat alfalfa sprouts due to the risk of more severe illness from possible E. coli contamination.

Discard bulging or dented cans and jars that are cracked or have loose or bulging lids -- do not open them or taste the contents. Also discard cans or jars that spurt liquid when opened.

Follow approved home-canning procedures, which can be obtained from the U.S. Department of Agriculture. Do not eat home-canned food if the seal is broken. Boil home-canned foods for 10 minutes before eating to ensure safety.

Drink water that has been treated with adequate levels of chlorine or other disinfectants. If you're camping or traveling, don't drink untreated water from streams or other sources. Protect your food and water from insects, rodents and other animals.

The Centers for Disease Control and Prevention recommends that people who have liver disease, diabetes or weak immune systems not eat raw oysters or clams. People in these groups are at higher risk for serious illness from a bacterium oysters may contain called Vibrio vulnificus.
Outbreak investigation
Public health officials investigate many food-borne illnesses. In an effort to prevent further illness, the source of infection is eliminate when possible. Contact your local health department if you or others have become ill from eating the same food.