Foodborne Illnesses: Types, Causes, Symptoms, and More

Foodborne illnesses — or food poisoning — are caused by consuming a food or beverage contaminated with a pathogen, such as a bacteria, virus, or parasite.

These illnesses cause a range of uncomfortable digestive symptoms and some may cause more severe symptoms that require hospitalization.

This article explains everything you need to know about foodborne illnesses, including their types, causes, and symptoms.

Foodborne illnesses 101

The Centers for Disease Control and Prevention (CDC) estimates that 48 million people get sick, 128,000 are hospitalized, and 3,000 die from foodborne illnesses each year in the United States (1).

Foodborne illnesses are cause by a hazard that gets into food.

This hazard may be chemical, physical, or biological.

Of these, biological food hazards are responsible for most foodborne illnesses, and there are four main types:

• bacteria
• viruses
• fungi
• parasites

Of the more than 250 known pathogens that cause foodborne illnesses, six spread easily through food and make people sick (1).

These six pathogens are known as the “Big 6,” and include:

• Norovirus
• Hepatitis A
• Shigella
• Shiga toxin-producing Escherichia Coli (STEC)
• Salmonella Typhi
• Salmonella (nontyphoidal)

The symptoms of foodborne illnesses vary but generally include:

• vomiting
• diarrhea
• nausea
• abdominal pain
• fever

The duration and severity of the symptoms also vary depending on the foodborne illness.

No person is immune from foodborne illnesses but highly susceptible populations are more likely to develop them and experience severe symptoms or require hospitalization from them.

Highly susceptible populations include:

• people with conditions that weaken the immune system (immunocompromised) like cancer
• preschool-aged children
• older adults
• pregnant women

Foodborne illnesses A to Z

Here’s an overview of common foodborne pathogens, the illnesses they cause, and the factors that define them (2):

Foodborne Pathogen (Illness)	Type	Symptom Onset	Symptoms	Symptom Duration	Common Sources
Bacillus cereus (B. cereus)	Bacteria	10–16 hours	Nausea, stomach cramps, watery diarrhea	24–48 hours	Gravies, meats, stews
Campylobacter jejuni (Campylobacteriosis)	Bacteria	2–5 days	Diarrhea (may be bloody), nausea, stomach pain, vomiting	2–10 days	Contaminated water, raw and undercooked poultry, unpasteurized milk
Clostridium botulinum (Botulism)	Bacteria	12–72 hours	Diarrhea, difficulty swallowing, muscle weakness, vomiting	Variable	Baked potatoes in foil, fermented fish, improperly canned foods
Clostridium perfringens (C. perfringens)	Bacteria	8–16 hours	Stomach cramps, watery diarrhea	24 hours	Gravies, meats, poultry
Cryptosporidium (Cryptosporidiosis)	Bacteria	2–10 days	Diarrhea, fever, stomach cramps	May be reoccurring over several weeks to months	Contaminated water, foods handled by an infected food handler, undercooked food
Escherichia coli 0157:H7 (E. coli)	Bacteria	1–8 days	Diarrhea (often bloody), stomach cramps, vomiting	5–10 days	Contaminated water, raw produce, undercooked beef, unpasteurized milk and juice
Escherichia coli Producing toxin	Bacteria	1–3 days	Diarrhea, stomach cramps, some vomiting	3–7 days	Water or food contaminated with human feces
Listeria monocytogenes (Listeriosis)	Bacteria	9–48 hours	Diarrhea, fever, flu-like symptoms in pregnant women, nausea	Variable	Deli meats, unpasteurized milk, soft cheese, deli meats
Salmonella (typhoidal salmonellosis)	Bacteria	1–3 weeks	Achiness, diarrhea, fever, stomach cramps	2–4 weeks	Contaminated produce, poultry, meat, unpasteurized milk or juice
Salmonella (nontyphoidal salmonellosis)	Bacteria	6–72 hours	Diarrhea, fever, nausea, stomach cramps	4–7 days	Contaminated produce, poultry, meat, unpasteurized milk or juice
Shigella (Shigellosis or Bacillary dysentery)	Bacteria	4–7 days	Diarrhea (may be bloody), fever, stomach cramps	24–48 hours	Contaminated water, foods handled by an infected food handler, raw produce, uncooked foods
Staphylococcus aureus (Staphylococcal)	Bacteria	1–6 hours	Diarrhea, nausea, stomach cramps, vomiting	24–48 hours	Cream pastries, potato and egg salads, unrefrigerated or improperly refrigerated meats
Vibrio species (V. parahaemolyticus or V. vulnificus)	Bacteria	1–7 days	Diarrhea, fever, nausea, stomach cramps, vomiting	2–8 days	Undercooked or raw seafood
Yersinia enterocolitica (Yersiniosis)	Bacteria	4–7 days	Diarrhea, stomach pain	1–3 weeks	Raw or undercooked pork
Hepatitis A (Hepatitis)	Virus	15–50 days	Dark urine, diarrhea, flu-like symptoms, jaundice, stomach pain	2–12 weeks	Contact with an infected food handler, raw produce, shellfish from contaminated water
Norovirus (Gastroenteritis or food poisoning)	Virus	12–48 hours	Diarrhea, stomach cramps, nausea, vomiting	12–60 hours	Foods handled by an infected food handler, raw produce, shellfish from contaminated waters
Cyclospora cayetanensis (Cyclosporiasis)	Parasite	7 days	Bloating, diarrhea, nausea, stomach cramps	May be recurring over several weeks to months	Baby lettuce, basil, raspberries
Giardia lamblia (Giardiasis)	Parasite	1–2 weeks	Diarrhea, stomach cramps, nausea	2–6 weeks	Foods handled by an infected food handler, contaminated water
Trichinella spiralis (Trichinosis)	Parasite	3–14 days	Chills, difficulty breathing, fever, muscle pain	5–45 days	Raw or undercooked pork

How foodborne illnesses occur and spread

Arising from food hazards, there are several ways that foodborne illnesses occur and spread.

Some of the most common ways include:

• purchasing food from unsafe sources
• failing to cook food adequately
• holding food at improper temperatures
• using contaminated equipment
• poor personal hygiene

Purchasing food from unsafe sources

The contamination of food with pathogens can occur at any step throughout the supply chain, including the environment where animals are raised and plants are grown and harvested, and during processing, packaging, and handling.

Preventing contamination isn’t always possible, but purchasing food from reputable suppliers that are inspected and meet all local, state, and federal food safety laws reduces this risk.

Failing to cook food adequately

Heat is able to destroy most of the bacteria and parasites that cause foodborne illnesses.

For this reason, foods have a minimum internal temperature that they must meet to kill these pathogens.

For example, poultry must be cooked to a minimum internal temperature of 165ºF (74ºC) while ground meats must be cooked to at least 155ºF (68ºC) for 17 seconds to kill off pathogens.

Undercooking foods allow these pathogens to survive which can then make you sick.

Holding food at improper temperatures

Bacteria multiply rapidly when food is between 41ºF (5ºC) and 135ºF (57ºC).

This range is known as the temperature danger zone.

Anytime that cold food is held above 41ºF (5ºC) or hot food is held below 135ºF (57ºC), the risk of bacteria growing to harmful levels increases significantly.

This is why you must hold hot at 135ºF (57ºC) or higher and cold foods at 41ºF (5ºC) or lower to keep them safe.

Foods that require time and temperature controls are known as TCS foods.

Using contaminated equipment

Cross-contamination can spread pathogens easily during food preparation.

Cross-contamination occurs when harmful bacteria are accidentally transferred from one food to the next.

It usually occurs when a food handler works with raw meats, poultry, or seafood and then switches to handling ready-to-eat (RTE) foods like cooked hot dogs, washed fruits or vegetables, salads, or sandwiches.

Cross-contamination can occur due to improper handwashing, touching food with your bare hands, or using the same equipment, utensils, or food preparation surface.

Poor personal hygiene

Proper handwashing is one of the best ways to prevent the spread of foodborne illnesses.

However, most food handlers don’t wash their hands correctly or when they’re supposed to, promoting the spread of pathogens.

Pathogens can get onto your hands after using the toilet or handling food that contains them.

Many people also carry pathogens like Staphylococcus aureus in their nasal cavities or on their skin.

In these scenarios, pathogens can easily spread to food without proper handwashing or glove use (3).

Preventing foodborne illnesses

Preventing foodborne illnesses from occurring and spreading is everyone’s responsibility.

Here are some key ways to do just that:

• wash your hands correctly and often
• wash fruits and vegetables
• cook food to the proper internal temperature
• limit the time food spends in the temperature danger zone
• avoid cross-contamination
• cool foods using the two-stage cooling method
• store foods at the proper temperature
• avoid bare hand contact with preparing or serving RTE foods
• throw leftovers out after seven days
• properly wash, rinse, and sanitize food equipment and dishware in a 3-compartment sink

The bottom line

Foodborne illnesses are caused by consuming a food or beverage contaminated by a pathogen, such as bacteria, virus, or parasite.

They cause digestive symptoms like diarrhea, vomiting, and nausea, and can be particularly harmful to susceptible populations like older adults and others with a weakened immune system.

Several factors contribute to their occurrence and spread, including purchasing food from unsafe sources, failing to cook food adequately, holding food at improper temperatures, using contaminated equipment, and poor personal hygiene.

You can prevent foodborne illness from occurring and spreading by washing your hands correctly and often, cooking food to the proper internal temperature, and storing foods correctly and at the right temperature, among other ways.