Foodborne Illness: How Food Gets Contaminated and What Helps

Each year about 48 million people in the United States get sick from contaminated food. Bacteria and viruses are the common causes; less often, it is a parasite or a harmful chemical, such as a large amount of pesticide.

Symptoms

Symptoms depend on the cause and can be mild or serious. They usually include:

• upset stomach;
• abdominal cramps;
• nausea and vomiting;
• diarrhea;
• fever;
• dehydration.

Most foodborne illnesses are acute: they come on suddenly and last a short time — from a few hours to several days.

Less often, some kinds — such as botulism and fish and shellfish poisoning — affect the nervous system, causing blurred vision, headache, weakness, tingling or numbness of the skin, or paralysis. Anyone with nervous-system symptoms should see a doctor or go to an emergency room right away.

Dehydration and when to get care

Dehydration is the most common complication. In adults, signs include extreme thirst and a dry mouth, urinating less than usual, dark urine, feeling tired, light-headedness or fainting, sunken eyes or cheeks, and skin that does not flatten straight back after a pinch. In an infant or young child, watch also for no wet diapers for 3 hours or more, no tears when crying, and a lack of energy.

Adults should see a doctor right away for:

• a change in mental state, such as confusion, irritability or a lack of energy;
• a high fever;
• frequent vomiting;
• six or more loose stools in a day, or diarrhea lasting more than 3 days;
• severe pain in the abdomen or rectum;
• stools that are black and tarry or contain blood or pus;
• signs of dehydration.

Older adults, pregnant women, and people with a weakened immune system or another health condition should see a doctor for any symptoms of food poisoning. Diarrhea is especially dangerous in newborns and infants, who can become severely dehydrated in a day or two; call a doctor for advice.

Where contamination happens

Food passes through several steps between the farm or fishery and the table, and it can become contaminated at any of them. For example:

• raw meat during slaughter;
• fruits and vegetables while growing or during processing;
• refrigerated foods left on a loading dock in warm weather.

It can also happen in your own kitchen, if food is left out at room temperature for more than 2 hours. Handling food safely can help prevent foodborne illness.

Treatment

Most people with foodborne illness get better on their own. The most important thing is to replace lost fluids and electrolytes to prevent dehydration:

• Adults can usually drink water, broth, sports drinks or diluted fruit juice; if vomiting is a problem, sip small amounts of clear liquid. Older adults, people with a weakened immune system, and anyone with severe diarrhea or signs of dehydration should use an oral rehydration solution — a drink containing glucose and electrolytes.
• Children should be given an oral rehydration solution as directed; talk with a doctor before giving one to an infant. Infants keep drinking breast milk or formula as usual.

When appetite returns, most people can go back to their normal diet, even while diarrhea continues.

Adults can sometimes use over-the-counter medicines for diarrhea, such as loperamide or bismuth subsalicylate, but not with bloody diarrhea or a fever — signs of a bacterial or parasitic infection that needs a doctor. These medicines can be dangerous for infants and children.

If a health care provider can identify the specific cause, medicines such as antibiotics or drugs that target parasites may treat it. Life-threatening complications, such as severe dehydration, hemolytic uremic syndrome or paralysis, are treated in hospital.

Sources

• MedlinePlus, U.S. National Library of Medicine, "Foodborne Illness," drawing on the National Institute of Diabetes and Digestive and Kidney Diseases. https://medlineplus.gov/foodborneillness.html
• National Institute of Diabetes and Digestive and Kidney Diseases, "Symptoms & Causes of Food Poisoning" and "Treatment for Food Poisoning." https://www.niddk.nih.gov/health-information/digestive-diseases/food-poisoning
• Rewritten in hubnx's own words.