A Complete Guide to Foodborne Illnesses

Foodborne illness is a serious, and preventable, risk. Millions of people get sick each year, leading to thousands of hospitalizations and even deaths. According to the CDC, the U.S. experiences roughly 10 million illnesses, 500,000 hospitalizations, and 900 deaths from foodborne diseases each year. For restaurants, prevention is business-critical: understanding causes, high-risk foods, and vulnerable guests helps protect customers and your brand.  

This guide explains what foodborne illness is, how it spreads, the steps to stop it, and how online food handler training can help you and your team reduce food contamination risks. 

What Is a Foodborne Illness?

A foodborne illness (food poisoning) is an infection or intoxication you get from eating or drinking something contaminated, typically with harmful microbes (bacteria, viruses, parasites) or their toxins/chemicals. Contamination can occur anywhere from farm to table, during production, storage, prep, or service. 

History of Food Safety

Food safety rules in the U.S. have steadily gotten better in an attempt to stop illness before it starts. Starting in 1906, the first national rules set basic food and meat inspections. Over the next decades, the FDA gained more authority. By 1938, it could set standards and inspect factories, and 20 years later, in 1958, companies had to prove food additives were safe. In the 1970s, the CDC began tracking outbreaks nationwide, and by 1996, DNA tools (PulseNet) and the USDA’s HACCP rule helped find and stop problems faster. Building on that progress, the 2011 Food Safety Modernization Act shifted the system toward prevention across farms, factories, and imports, and in 2020, a new FDA plan pushed quicker tracking and digital tools. Better detection today can make illness counts look higher, but these changes all aim at one goal: fewer outbreaks and safer food—the focus of this guide. 

What Are the Different Types of Foodborne Illness?

Foodborne illness happens in three main ways. Infections occur when you swallow live germs that grow in your body. Examples of infection include: 

• Salmonella 

• E. coli 

• Listeria 

• Viruses: norovirus, hepatitis A 

Intoxications happen when you eat toxins already made in the food. This includes: 

• Staphylococcal (Staph) toxin 

• Bacillus cereus toxin (often from improperly cooled rice) 

• Botulinum toxin from unsafe canning 

• Fish toxins: ciguatera, scombroid 

Toxicoinfections are when you swallow germs that then make toxins in your gut. Some examples of toxicoinfections are: 

• Clostridium perfringens 

• Diarrheal-type Bacillus cereus 

What Are the Symptoms of Foodborne Illness?

Since foodborne illness is a broad category, the symptoms vary heavily by cause. 

There are some outliers. Botulism, a foodborne intoxication, causes muscle weakness or paralysis. Tapeworms, an infectious parasite, cause increased appetite paired with weight loss. 

However, the most common symptoms for all types of foodborne illness follow the formula of the "stomach flu." Sometimes after eating contaminated food, you come down with diarrhea, vomiting, and/or stomach cramps, usually within 12-72 hours. 

You may get over it in 24 hours, or symptoms can last as long as weeks, depending on the bug, like E. coli or cholera. 

Which Groups Are Most Likely to Be Affected by Foodborne Pathogens?

Some people are more prone to foodborne infections because of their immune system.  Individuals with weaker or developing immune systems are at increased risk, including: 

• Pre-school-aged children (5 and under) whose immune systems are still developing 

• Older adults (65 and up) whose immune systems are in decline 

• Pregnant women, whose immune system is altered to protect the fetus 

• Anyone whose immune system is compromised by a disease or medical treatment (HIV, medications) 

Public health experts call these Highly Susceptible Populations (HSPs), and the CDC recommends that food service operations that serve HSPs take the most stringent precautions. 

Young, healthy adults, on the other hand, tend to be the least vulnerable.  They may have modest symptoms or recover rapidly. But high amounts of certain viruses or illnesses, like Hepatitis A, can still cause serious illness or even lead to a hospitalization. 

Essential Guidelines for Preventing Foodborne Illness

As a food handler, you are often what stands between your patrons and foodborne illness. That is why small measures like storage, temperature control, and sanitation play such a big role in stopping infections. Here are some quick tips to put those measures into daily practice: 

Cooking at Ideal Temperatures 

• Use a calibrated probe thermometer every time. 

• Key minimum internal temps (°F): 165 poultry and leftovers; 160 ground meats; 145 whole cuts of beef/pork/veal/lamb (let rest 3 minutes); 145 fish. 

• Check the thickest part and avoid touching bone or pan. 

• Never “partially cook” and finish later. 

Kitchen Hygiene 

• Wash hands with warm water and soap for 20 seconds (before food prep; after raw foods, trash, bathroom, phone, or breaks). 

• Gloves don’t replace handwashing—wash first, then change gloves often. 

• Clean, then sanitize food-contact surfaces between tasks; let sanitizer air-dry per the label. 

• Do not work with food if you’re ill (vomiting, diarrhea, fever). 

Refrigerator Cleanliness 

• Keep refrigerators at 40°F or below; freezers at 0°F or below; use appliance thermometers. 

• Wipe spills right away; cover and label/date all items; don’t overpack shelves (air must circulate). 

• FIFO: use older items first. Schedule weekly deep cleans of shelves, drawers, and gaskets. 

Avoid Cross-Contamination 

• Store in this top-to-bottom order: ready-to-eat foods → seafood → whole cuts → ground meats → poultry on the bottom. 

• Use separate, color-coded boards/knives for raw and ready-to-eat foods. 

• Change gloves and wash hands when switching tasks; sanitize tools between uses. 

Careful Food Purchasing 

• Buy from reputable, approved suppliers. 

• Check use-by/expiration dates and packaging: no dents, bulges, leaks, rust, or broken seals. 

• Keep the cold chain: pick up refrigerated/frozen foods last and transport quickly (use coolers/ice packs if needed). 

• Reject items with off odors, signs of thaw/refreeze, or damaged labels. 

How Restaurants Manage Food Safety

Restaurants play a critical role in spreading or preventing foodborne illness. According to the CDC, 70% of reported norovirus outbreaks can be traced back to food service facilities. 

Restaurants need a comprehensive plan to tackle all the different ways foodborne illness can pass through their kitchen. Here are some restaurant-specific practices to put that plan into action.  

Allergen Safety 

Prevent reactions by standardizing how you identify, prepare, and serve allergen orders. Be sure to ask guests clarifying questions, flag tickets and use dedicated utensils/areas to avoid cross-contamination. You should also train staff on symptoms and your response plan.  

Safe Equipment 

Use NSF/ANSI–certified food equipment and surfaces that are smooth, durable, nonabsorbent, and easily cleanable; this reduces harborage points and speeds effective sanitizing. Add helpful tech—probe thermometers, data-logging coolers, and dish machines with built-in temperature/sanitizer readouts—to keep temps and sanitizing within spec.  

Manage Waste  

Build a simple IPM routine: keep refuse containers covered and sized for volume, remove trash frequently, clean dumpster pads, seal gaps/doors, and document pest sightings and corrective actions. Good waste control reduces rodent/insect attraction and supports a passing inspection.  

Ensure Regulatory Adherence 

Align policies with your jurisdiction’s adoption of the FDA Food Code (state and local health departments often incorporate it, sometimes with additions). Confirm requirements like Certified Food Protection Manager presence, employee-health rules, and date-marking via your state/local authority.  

Continuous Training 

Reinforce day-to-day behaviors with role-specific training and credentialing such as: 

Food Handler Training for front-line staff.  

Food Safety Manager Training for managers and supervisors.  

Food Allergen Awareness to prevent and respond to allergen risks. 
 
from time and temperature control procedures to practices that prevent cross contamination. A huge part of this plan is a comprehensive training strategy for all food contact employees and in-depth certification for their managers. 

Get Started With Learn2Serve

At Learn2Serve by 360training, we have over 20 years of experience providing online courses for various roles and industries.  

We offer in-depth food safety training for managers as well as a national food handler course for other food service workers. Get started today! 

What are the Symptoms of Foodborne Illness?

Since foodborne illness is a broad category, the symptoms vary heavily by cause.

There are some weirdos. Botulism (a foodborne intoxication) causes muscle weakness or paralysis. Tapeworms (an infectious parasite) cause increased appetite paired with weight loss.

However, the most common symptoms for all types of foodborne illness follow the formula of the "stomach flu." Sometimes after eating contaminated food, you come down with diarrhea, vomiting, and/or stomach cramps (usually within 12-72 hours).

You may get over it in 24 hours, or symptoms can last as long as weeks depending on the bug, like E. coli or cholera.

Why Does Foodborne Illness Present That Way?

There are two reasons that food poisoning usually causes diarrhea and vomiting.

Sometimes these symptoms are defensive. If your body recognizes that you've eaten something harmful, it wants to expel the substance or pathogen as quickly as possible. If the alarm sounds before the small intestine, food goes back up; intruders are fast-tracked down after it enters the small intestine.

This is also why seeing and smelling spoiled food makes you nauseous – your body hopes to put you off eating altogether, but if you don't listen, you're primed to eject the "poison" right away.

Other times, these symptoms are a pathogen's offense. Foodborne pathogens usually stick to doing business where they came in – your digestive tract. They enter there, reproduce there, and then hijack your body's defenses to help them exit there.

Giving you an urgent need to vomit is a great way to ensure you're around other people when you do. Pathogens that cause diarrhea bank on poor bathroom hygiene to let them hitchhike their way to a new friend.

What Are the Main Causes of Foodborne Illness?

Most foodborne illnesses are infectious.

What Are the Most Common Foodborne Infections?

The biggest cause of all foodborne illness is norovirus, which is hard to kill and easy to spread. It accounts for more than half of U.S. food poisoning cases.

After norovirus, most foodborne illnesses are caused by four types of bacteria: Salmonella, Clostridium perfringens, Campylobacter, and Staphylococcus aureus.

What Are the Most Dangerous Foodborne Infections?

Some pathogens are less common to get, but more likely to cause severe illness. Your chances of being hospitalized are high if you're exposed to E. coli, botulinum toxin (produced by Clostridium botulinum), Listeria, or Vibrio.

What Foods Are Most Likely to Give You Food Poisoning?

The CDC's analysis of foodborne illness outbreaks between 1998 and 2008 found that leafy vegetables were the largest culprit.

In fact, produce – including leafy vegetables, root vegetables, sprout vegetables, and vine-stalk vegetables – accounted for almost half of all foodborne illnesses in the study.

However, even though meat and poultry sources caused fewer illnesses, they accounted for more deaths.

Who is Susceptible to Foodborne Illness?

Anyone can come down sick with a foodborne illness, but some people are more likely than others to be exposed or show severe symptoms.

Who is Most Likely to Be Exposed to Foodborne Illness?

Your habits (and those of the society you live in) can increase or decrease the likelihood that you'll be exposed to pathogens, toxins, or chemicals in your food that will make you sick.

Individual factors that increase your risk include:

• Consuming raw milk (the pasteurization process is designed to kill foodborne pathogens)
• Consuming foods that have been canned, preserved, or fermented improperly (or eating any of these from damaged containers)
• Not washing leafy greens and other vegetables intended for raw consumption
• Eating undercooked meat
• Feeding honey to an infant

Community factors include:

• Poor separation of human waste from food and water sources (no sewer system)
• Weak regulatory mechanisms for food safety and environmental protection

Which Groups Are Most Likely to Be Infected When Exposed to Foodborne Pathogens?

If your immune system is strong, you may be able to fight off a foodborne infection without any symptoms. If you're immunocompromised, it's more likely that even a small number of pathogens will overwhelm your immune system.

Demographically, some groups of people are more likely to get sick with the stomach flu and have a more severe set of symptoms because of their immune status. That includes:

• Pre-school aged children (5 and under) whose immune systems are still developing
• Older adults (65 and up) whose immune systems are in decline
• Pregnant women, whose immune system is altered to protect the fetus
• Anyone whose immune system is compromised by a disease or medical treatment (HIV, medications)

Public health experts call these Highly Susceptible Populations (HSPs), and the CDC recommends that food service operations that serve HSPs take the most stringent precautions.

Which Groups Are Least Susceptible to Foodborne Illnesses?

Young, healthy adults are the least susceptible to foodborne illness.

This doesn't mean this group can't get sick. Instead, they may end up with very mild symptoms (like an ominously rumbly tummy) or recover quickly from an acute illness.

They're the least likely to end up hospitalized or dead due to foodborne illness.

However, large enough doses of the disease-causing agent (or certain virulent foodborne illnesses) can still land young, healthy adults in the hospital, like Hepatitis A.

How Do Restaurants Prevent Foodborne Illness?

Restaurants play a critical role in spreading or preventing foodborne illness. According to the CDC, 70% of reported norovirus outbreaks can be traced back to food service facilities.

Restaurants need a comprehensive plan to tackle all the different ways foodborne illness can pass through their kitchen – from time and temperature control procedures to practices that prevent cross-contamination. A huge part of this plan is a comprehensive training strategy for all food contact employees and in-depth certification for their managers.

Naturally, the cost and logistics of training are always a concern, but reputable online training can provide the best of all worlds. At Learn2Serve by 360training, we have over 20 years of experience providing online coursework and ANSI-CFP accreditation and regulatory approval in many states.

Start with in-depth food safety training for your managers, like ANSI Food Protection Manager Certification. Then provide effective food handler training for your entire staff, whether local regulations require it.

And while COVID-19 rages and food delivery takes up a chunk of your business, Health and Sanitation Safety Awareness (HASSA) certification can help managers and employees keep up with the special food safety demands of these strange times.