Food poisoning, also called food borne illness, is an illness caused by eating contaminated food. Infectious organisms including bacteria, viruses and parasites or their toxins are the most common causes of food poisoning.
Infectious organisms or their toxins can contaminate food at any point of processing or production. Contamination can also occur at home if food is incorrectly handled or cooked.
Food poisoning symptoms, which can start within hours of eating contaminated food, often include nausea, vomiting or diarrhea. Most often, food poisoning is mild and resolves without treatment. But some people need to go to the hospital.
Symptoms
Food poisoning symptoms vary with the source of contamination. Most types of food poisoning cause one or more of the following signs and symptoms:
Nausea
Vomiting
Watery or bloody diarrhea
Abdominal pain and cramps
Fever
Signs and symptoms may start within hours after eating the contaminated food, or they may begin days or even weeks later. Sickness caused by food poisoning generally lasts from a few hours to several days.
When to see a doctor
If you experience any of the following signs or symptoms, seek medical attention.
Frequent episodes of vomiting and inability to keep liquids down
Bloody vomit or stools
Diarrhea for more than three days
Extreme pain or severe abdominal cramping
Signs or symptoms of dehydration — excessive thirst, dry mouth, little or no urination, severe weakness, dizziness, or lightheadedness
Neurological symptoms such as blurry vision, muscle weakness and tingling in the arms
Causes
Contamination of food can happen at any point of production: growing, harvesting, processing, storing, shipping or preparing. Cross-contamination — the transfer of harmful organisms from one surface to another — is often the cause. This is especially troublesome for raw, ready-to-eat foods, such as salads or other produce. Because these foods are not cooked, harmful organisms are not destroyed before eating and can cause food poisoning.
Many bacterial, viral or parasitic agents cause food poisoning. The following table shows some of the possible contaminants, when you might start to feel symptoms and common ways the organism is spread.
Risk factors
Whether you become ill after eating contaminated food depends on the organism, the amount of exposure, your age and your health. High-risk groups include:
Older adults. As you get older, your immune system may not respond as quickly and as effectively to infectious organisms as when you were younger.
Pregnant women. During pregnancy, changes in metabolism and circulation may increase the risk of food poisoning. Your reaction may be more severe during pregnancy. Rarely, your baby may get sick, too.
Infants and young children. Their immune systems have not fully developed.
People with chronic disease. Having a chronic condition — such as diabetes, liver disease or AIDS — or receiving chemotherapy or radiation therapy for cancer reduces your immune response.
Complications
The most common serious complication of food poisoning is dehydration — a severe loss of water and essential salts and minerals. If you’re a healthy adult and drink enough to replace fluids you lose from vomiting and diarrhea, dehydration should not be a problem.
Infants, older adults and people with suppressed immune systems or chronic illnesses may become severely dehydrated when they lose more fluids than they can replace. In that case, they may need to be hospitalized and receive intravenous fluids. In extreme cases, dehydration can be fatal.
Some types of food poisoning have potentially serious complications for certain people. These include:
Listeria infection. Complications of a listeria food poisoning may be most severe for an unborn baby. Early in pregnancy, a listeria infection may lead to miscarriage. Later in pregnancy, a listeria infection may lead to stillbirth, premature birth or a potentially fatal infection in the baby after birth — even if the mother was only mildly ill. Infants who survive a listeria infection may experience long-term neurological damage and delayed development.
E. coli: Certain E. coli strains can cause a serious complication called hemolytic uremic syndrome. This syndrome damages the lining of the tiny blood vessels in the kidneys, sometimes leading to kidney failure. Older adults, children younger than 5 and people with weakened immune systems have a higher risk of developing this complication. If you’re in one of these risk categories, see your doctor at the first sign of profuse or bloody diarrhea.
Prevention
To prevent food poisoning at home:
Wash your hands, utensils and food surfaces often. Wash your hands well with warm, soapy water before and after handling or preparing food. Use hot, soapy water to wash utensils, cutting boards and other surfaces you use.
Keep raw foods separate from ready-to-eat foods. When shopping, preparing food or storing food, keep raw meat, poultry, fish and shellfish away from other foods. This prevents cross-contamination.
Cook foods to a safe temperature. The best way to tell if foods are cooked to a safe temperature is to use a food thermometer. You can kill harmful organisms in most foods by cooking them to the right temperature.
Refrigerate or freeze perishable foods promptly — within two hours of purchasing or preparing them. If the room temperature is above 90 F (32.2 C), refrigerate perishable foods within one hour.
Defrost food safely. Don’t thaw food at room temperature. The safest way to thaw food is to defrost it in the refrigerator. If you microwave frozen food using the “defrost” or “50% power” setting, be sure to cook it immediately.
Throw it out when in doubt. If you aren’t sure if a food has been prepared, served or stored safely, discard it. Food left at room temperature too long may contain bacteria or toxins that can’t be destroyed by cooking. Don’t taste food that you’re unsure about — just throw it out. Even if it looks and smells fine, it may not be safe to eat.
Food poisoning is especially serious and potentially life-threatening for young children, pregnant women and their fetuses, older adults, and people with weakened immune systems. These individuals should take extra precautions by avoiding the following foods:
Raw or rare meat and poultry
Raw or undercooked fish or shellfish, including oysters, clams, mussels and scallops
Raw or undercooked eggs or foods that may contain them, such as cookie dough and homemade ice cream
Raw sprouts, such as alfalfa, bean, clover and radish sprouts
Unpasteurized juices and ciders
Unpasteurized milk and milk products
Soft cheeses, such as feta, Brie and Camembert; blue-veined cheese; and unpasteurized cheese
Refrigerated pates and meat spreads
Uncooked hot dogs, luncheon meats and deli meats
At the end of the day what matters is to always take precautions and keep a healthy, clean and safe environment
