Understanding the Contagious Nature of Food Poisoning

The Centers for Disease Control and Prevention (CDC) estimates that 48 million people in the United States get sick from foodborne diseases annually, with 128,000 requiring hospitalization and 3,000 dying as a result. Beyond the toll on public health, foodborne illnesses contribute to a significant economic burden, with costs exceeding $15 billion annually related to medical expenses and lost productivity.

While food poisoning is primarily associated with bad food, the truth is that some forms can be highly contagious, spreading from person to person. This article will explore the contagious nature of food poisoning and how we can reduce the spread of harmful pathogens.

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What Is Food Poisoning?

Food poisoning (foodborne illness) occurs when food or beverages contaminated with harmful microorganisms, toxins, or chemicals are consumed. This causes infection and/or inflammation in the gastrointestinal (GI) tract, called acute gastroenteritis. 

Common Causes of Food Poisoning

Most cases of food poisoning are caused by food contaminated with an infectious microbe:

• Bacteria
• Virus
• Parasite

In the United States, the top five causes of food poisoning are:

• Norovirus (virus)
• Non-typhoidal Salmonella (bacteria)
• Clostridium perfringens (bacteria)
• Campylobacter (bacteria)
• Staphylococcus aureus (bacteria)

Sometimes, toxins or chemicals in food can cause food poisoning by irritating the GI tract, leading to acute symptoms. These substances can enter food through pesticides or be produced by bacteria, mold, or algae in food. 

Frequently contaminated foods include: 

• Fresh, unwashed produce
• Raw or undercooked meat, poultry, and eggs
• Unpasteurized/raw dairy products
• Seafood
• Deli foods
• Improperly canned foods

Risk Factors for Food Poisoning

The following groups are at a higher risk of developing severe illness from food poisoning:

• People ages 65 and older
• Children younger than 5
• People with weakened immune systems due to diabetes, liver disease, kidney disease, alcoholism, HIV infection, autoimmune disease, or chemotherapy/radiation therapy. 
• People who are pregnant

Symptoms of Food Poisoning

The onset and type of food poisoning symptoms can vary depending on the specific pathogen involved, but they typically include: 

• Abdominal pain and cramping
• Nausea and vomiting
• Diarrhea
• Fever
• Loss of appetite
• Fatigue

Symptoms usually begin within hours to days of consuming contaminated food or drink. Most people get better on their own without medical treatment in less than a week. 

Is Food Poisoning Contagious?

A contagious disease is one that can spread from an infected person to a healthy one. 

Pathogens That Spread Person-to-Person

Certain pathogens are notorious for being highly contagious. Examples include: 

• Norovirus: This highly contagious virus is the number one cause of foodborne illness in the United States. Because it is easily spread through contact with an infected person, contaminated food, or surfaces touched by infected individuals, it is often responsible for outbreaks in places like cruise ships, schools, and nursing homes.
• E. coli (Escherichia coli): While some strains of E. coli are harmless, there are six strains that can cause diarrheal infections in the GI tract. Shiga toxin-producing E. coli (STEC) is the most common cause of E. coli outbreaks and illness in the U.S., causing 265,000 infections annually. These pathogens can spread person-to-person through poor hygiene, particularly if someone handles food after touching contaminated surfaces.
• Salmonella: Salmonella is the most common type of bacterial food poisoning in the United States. The most common way to get salmonella is by eating undercooked or improperly prepared food contaminated with Salmonella bacteria, but it can also spread through person-to-person contact.
• Shigella: This bacterium is responsible for causing shigellosis and is easily spread. People can get shigellosis by eating contaminated food, drinking contaminated water, coming into contact with the stool of an infected person, or through sexual contact with an infected person.
• Hepatitis A: The hepatitis A virus is highly contagious and causes hepatitis A liver disease. It is spread by eating contaminated food or drink and close person-to-person contact. 

How Does Food Poisoning Spread?

Food contamination can happen at any stage of food production and manufacturing, from growing to preparation. Microbes naturally grow on food, which is why it spoils over time. Without proper measures to slow microbial growth, these organisms can multiply quickly and contaminate food. Contamination can also occur if food or water is exposed to harmful microbes. 

You can get food poisoning if you consume food or water that isn't: 

• Fresh
• Washed properly 
• Handled in sanitary conditions
• Cooked and stored at safe temperatures

Mechanisms of Foodborne Illness Spread

Disease transmission is categorized as direct or indirect, and foodborne illness can spread through both types.

Direct transmission occurs through direct physical contact. Pathogens can easily transfer to someone's hands when they have diarrhea and are vomiting due to food poisoning. If the infected person (person A) touches another individual (person B) with unwashed hands, person B can become sick if they touch their mouth or eat food with unwashed hands. 

Indirect transmission happens when pathogens spread through intermediaries, such as contaminated objects, surfaces, or air, rather than direct contact. For instance, foodborne illness can spread indirectly when person A touches shared objects (e.g., door handles, countertops, or kitchen utensils) and leaves the pathogen behind on those surfaces. If healthy person B then touches these surfaces and subsequently touches their mouth with unwashed hands, they may ingest the pathogen and become sick.

Prevention and Safety Tips

Following these tips can reduce the risk of foodborne illness.

Proper Food Handling Practices

Practicing safe food handling techniques is the best way to prevent food poisoning. The CDC recommends these four steps: 

1. Clean

• Wash your hands for at least 20 seconds with soap and warm water before and after preparing food and before eating.
• Always wash your hands after touching uncooked meat, seafood, flour, or eggs.
• After preparing your food, wash all utensils and surfaces with hot, soapy water.
• Rinse raw fruits and vegetables with water before eating them.

2. Separate

• Keep raw meat, seafood, and eggs separate from fresh foods to prevent the spread of germs.
• Store raw meat, seafood, and eggs in separate, sealed containers in the refrigerator.
• When preparing foods, use separate surfaces for preparing raw meat/seafood and other foods.

3. Cook

• Cook food to internal temperatures high enough to kill the germs that can make you sick. Use a food thermometer to test the internal temperature before eating. 
• Cook beef, veal, lamb, pork, and fish to 145°F.
• Cook ground meat to 160°F.
• Cook poultry to 165°F.
• Reheat leftovers to 165°F.

4. Chill

• Bacteria will grow when left to sit at temperatures between 40°F and 140°F.
• Refrigerate perishable food within 2 hours or 1 hour if exposed to temperatures above 90°F.
• Keep your refrigerator at 40°F or below and your freezer at 0°F or below. 

Hygiene and Sanitation Measures

Pay attention to announcements of foodborne illness outbreaks and food recalls in your area. Dispose of any recalled items that you may have purchased.

Good hygiene practices can help prevent the spread of contagious infections between people: 

• Wash hands frequently, especially after tending to a sick person, using the bathroom, changing a diaper, or before/after handling food.
• Disinfect shared surfaces regularly.
• Use clean utensils.

When to Seek Medical Help

Talk to a doctor if you suspect you have food poisoning and are pregnant or have any of the following symptoms:

• Bloody diarrhea
• Diarrhea that lasts for more than three days
• Fever over 102°F
• Severe vomiting that prevents you from keeping liquids down

Dehydration is the most common complication of food poisoning, caused by frequent vomiting and diarrhea. Severe dehydration requires medical attention because it can cause electrolyte imbalances, heatstroke, kidney issues, shock, and even death. You should see a doctor if you have any of these symptoms of dehydration:

• Extreme thirst
• Urinating less than usual
• Dark urine
• Dry mouth
• Dizziness
• Confusion
• Sunken eyes or cheeks
• Seizures

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Key Takeaways

• Food poisoning is a prevalent public health concern in the United States.
• Food poisoning is caused by eating or drinking food or water contaminated with infectious pathogens, chemicals, or toxins. 
• A person sick with food poisoning can spread infectious germs to other people through direct and indirect contact.
• Taking proper preventive measures, including safe food handling, proper food storage, and good hygiene, can go a long way in reducing the risk of foodborne illness.