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Eight Most Common Types of Foodborne Pathogens

Today’s news headlines often include stories of outbreaks ...

… of foodborne illnesses that can be attributed to a variety of viruses, bacteria or parasites. Whether the outbreak takes place on a cruise ship, in a local community, a healthcare facility, or at a family reunion, there is a short list of pathogens that medical professionals look at to narrow down the type of outbreak that may be occurring.

Educating yourself on the primary types of foodborne pathogens and their symptoms is the first step to protecting both you and your loved ones.

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What is the Definition of a Foodborne Illness?

A foodborne illness (or food poisoning) is typically any illness that results from contaminated food. Fortunately, most foodborne illnesses resolve within a short time and without significant adverse health consequences.

However, all of types of foodborne illnesses present an elevated risk of hospitalization, debilitating medical conditions or even death, especially in infants, those over 65, or anyone who is immuno-compromised or has a pre-existing condition, such as diabetes, liver or kidney disease.

Understanding the most common types of foodborne pathogens and their symptoms will give you the information you need to make the right choices when you feel that you or someone you know may be suffering the consequences of a foodborne event.

Having this information will help you determine when it’s the right time to seek further medical advice from a family doctor or even a local emergency room.

Causes of Food Poisoning

Of the eight most common types of foodborne illnesses (also called food poisoning or foodborne disease) contracted in the US, six are bacterial in nature and generally non-fatal. The major pathogens that are deemed most serious include listeria, salmonella and parasitic toxoplasmosis.

Our aim at Stop Foodborne Illness is to provide you with information on the kind of foodborne pathogens that affect 1 in 6 Americans every year. Our goal is to answer your most urgent questions surrounding these types of illnesses, including:

  • How do these sometimes-deadly pathogens get into our food and agricultural systems?
  • How do I avoid getting sick?
  • What are the most common and deadly foodborne pathogens?


Type of Foodborne Illness > Bacterial

What is Campylobacter and its symptoms?

Campylobacteriosis is an infectious disease caused by a bacterium called Campylobacter. When people become ill with campylobacteriosis they typically get diarrhea, cramping, abdominal pain, and fever within two to five days after exposure. The diarrhea may be bloody and can be accompanied by nausea and vomiting.

The illness typically lasts about one week. Some infected people don’t have any symptoms. In those with compromised immune systems, Campylobacter occasionally spreads to the bloodstream and causes a serious life-threatening infection.

Infection occurs most commonly by ingestion of the bacteria via contaminated food or water, particularly raw or undercooked meats (especially poultry) or raw milk, and from contact with pets (especially puppies and kittens), farm animals, and infected infants.

Who is affected by Campylobacter?

Campylobacter can affect anyone; however, the most vulnerable are very young children (5 years and under) and older adults.

You can help prevent exposure to campylobacter—and ALL harmful pathogens that cause foodborne illness—by diligently practicing food safety basics like proper hand washing, keeping food prep areas clean, and cooking meats to safe temperatures.

Type of Foodborne Illness > Bacterial

What is Clostridium perfringens?

Clostridium perfringens (C. perfringens) is a bacterium found in many environmental sources and in the intestines of humans and animals. C. perfringens is commonly found on raw meat and poultry. It grows best in conditions with very little or no oxygen, and, under ideal conditions, it can multiply very rapidly. Some strains of C. perfringens produce a toxin in the intestine that causes illness.

What are the symptoms of C. perfringens?

People infected with C. perfringens develop diarrhea and abdominal cramps within 6 to 24 hours (typically 8 to 12 hours). Symptoms from Clostridium perfringens usually begins suddenly and last for less than 24 hours. People infected with C. perfringens usually do not have fever or vomiting.

Who is susceptible to C. perfringens?

Everyone is susceptible to becoming ill from C. perfringens.

The very young and elderly are most at risk, though, and can experience more severe symptoms that may last for one to two weeks.

Complications, including dehydration, may occur in severe cases.

Type of Foodborne Illness > Bacterial

Escherichia coli (E. coli) are a large and diverse group of bacteria. Although most strains of E. coli are harmless, others can make you sick. Some E. coli can cause diarrhea, while others cause urinary tract infections, respiratory illness, pneumonia and other illnesses.

Some of the most harmful E. coli strains cause disease by making a toxin called Shiga toxin. These are called “Shiga toxin-producing” E. coli, or STEC. You might hear these bacteria called verocytotoxic E. coli (VTEC) or enterohemorrhagic E. coli (EHEC).

They refer to the same group of bacteria. The STEC strain E. coli O104:H4 that caused a large outbreak in Europe in 2011 was frequently referred to as EHEC. The most identified STEC in North America is E. coli O157:H7 (often shortened to E. coli O157 or even just “O157”).

When you hear news reports about outbreaks of E. coli infections, they’re usually talking about E. coli O157.

What are the symptoms of E. coli O157?

Symptoms of STEC infections vary for each person but often include severe stomach cramps, diarrhea (often bloody), and vomiting. Some types of STEC frequently cause severe disease, including hemolytic uremic syndrome (HUS), which is a type of kidney failure. If fever is present, it usually isn’t very high (less than 101˚F). Most people get better within five to seven days. Some infections are very mild, but others are severe or even life-threatening.

Who gets E. coli?

People of any age can become infected with E. coli. Very young children and the elderly are more likely to develop severe illness and HUS than others, but even healthy older children and young adults can become seriously ill.

Type of Foodborne Illness > Bacterial

What is Listeria?

Listeriosis is a serious infection usually caused by eating food contaminated with the bacteria Listeria monocytogenes.

Someone with listeriosis usually has fever and muscle aches, which are sometimes preceded by diarrhea or other gastrointestinal (GI) symptoms. Almost everyone diagnosed with listeriosis has an “invasive” infection where the bacteria spreads beyond the GI tract.

What are the symptoms of Listeria?

Symptoms vary with cases of Listeria monocytogenes, but typical symptoms include fatigue,  headache, stiff neck, confusion, loss of balance, and convulsions, in addition to fever and muscle aches and body aches.

Pregnant women typically experience fever, however, it’s important to understand that infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn. In older adults and people with immunocompromised conditions, septicemia and meningitis are the most common clinical presentations.

Who is susceptible to Listeria?

Listeria primarily affects older adults, pregnant women, newborns, and adults with weakened immune systems. However, people outside of these groups can also get sick.

Type of Foodborne Illness > Viral

Norovirus is a very contagious virus that can infect anyone.

You can get it from an infected person, contaminated food or water, or by touching contaminated surfaces. The virus causes your stomach or intestines or both to get inflamed.

There is no vaccine for norovirus prevention and since antibiotics do not work on viruses, they won’t work on norovirus.

There are many types of norovirus, so you can get infected and sick many times in your life.

What are the symptoms of Norovirus?

Symptoms of norovirus vary, but those infected tend to have a mix of low-grade fever, chills, headache, muscle aches and fatigue.

In addition, norovirus outbreaks typically produce nausea, (more often in children), watery diarrhea (more often in adults), and stomach cramps.

The CDC estimates there are 19-21 million cases every year. Average incubation is 12-48 hours. Symptoms typically resolve within 1-3 days in healthy persons.

Who is affected by Norovirus?

Having norovirus can be serious for some people, especially young children and older adults, who are most vulnerable.

Learning how to prevent norovirus and what to look for in symptoms is the key to managing the illness.

Type of Foodborne Illness > Bacterial

What is Salmonella and its symptoms?

Salmonella is a bacteria commonly found in raw food products that come from animals such as eggs and egg products, meat and meat products, unpasteurized milk or other unpasteurized (raw) dairy products.

Most people infected with Salmonella develop diarrhea, fever and abdominal cramps between 12 and 72 hours after infection. The illness usually lasts four to seven days, and most individuals recover without treatment.

In some cases, diarrhea may be so severe that the infected person needs to be hospitalized. For these people, the Salmonella infection may spread from the intestines to the blood stream and then to other body sites. Unless the person is treated promptly with antibiotics this could ultimately cause death.

Who is Most at Risk?

Anyone can get salmonella poisoning, but the people most at risk for a severe salmonella infection are older adults, infants and those with impaired immune systems.

Type of Foodborne Illness > Bacterial

What is Staphylococcus aureus?

Staphylococcus aureus (Also known as Staph or S. aureus) is a common bacterium found on the skin and in the noses of up to 25% of healthy people and animals. Usually, it causes no illness in healthy people unless it’s transmitted to food products. However, staph has the potential to be a very harmful pathogen because it can make several types of toxins, many of which are responsible for food poisoning.

Staphylococcal food poisoning is a gastrointestinal illness. It’s caused by eating foods contaminated with toxins produced by staph. Food workers who carry staph and then handle food without washing their hands contaminate foods by direct contact.

The bacterium can also be found in unpasteurized milk and cheese products. Staph toxins are resistant to heat, so they can’t be destroyed by cooking. Foods at highest risk of producing toxins from staph are those that are made by hand and require no cooking like sliced meat, puddings, pastries, and sandwiches.

What are the symptoms of a staph infection?

Staph toxins are fast-acting, sometimes causing illness in as little as 30 minutes after eating contaminated foods, however, symptoms usually develop within one to six hours. People infected typically experience several of the following symptoms: nausea, vomiting, stomach cramps, and diarrhea.

Many instances of Staphylococcus aureus are known as MRSA, which means methicillin-resistant staphylococcus aureus.

The symptoms of a MRSA infection depend on the part of the body that is infected. For example, people with MRSA skin infections often can get swelling, warmth, redness, and pain in infected skin. In most cases it is hard to tell if an infection is due to MRSA or another type of bacteria without laboratory tests that your doctor can order. 

Most S. aureus skin infections, including MRSA, appear as a bump or infected area on the skin that might be red, swollen, painful, warm to the touch, full of pus/other drainage, or accompanied by a fever.

Who is susceptible to staph food poisoning?

Everyone is at risk for developing staph food poisoning, so it’s important to understand the symptoms, warning signs and places where infection could begin.

Type of Foodborne Illness > Parasitic

What is Toxoplasma?

Toxoplasmosis is a leading cause of death attributed to foodborne illness in the United States.

More than 60 million men, women and children in the U.S. carry the toxoplasma parasite, but very few have symptoms because the immune system usually keeps the parasite from causing illness.

What are the symptoms of Toxoplasma?

Most people infected with Toxoplasma gondii  are not aware of it because they have no symptoms at all.

In healthy people who aren’t pregnant, mild “flu-like” symptoms such as muscle aches, mild fever and tender lymph nodes typically occur if illness comes about. Those symptoms can last for weeks to months but then usually go away.

If someone is immunosuppressed, the illness can become reactivated. Severe toxoplasmosis, causing damage to the brain, eyes, or other organs, can develop from an acute Toxoplasma infection or one that had occurred earlier in life and is now reactivated. 

Who is Most at Risk?

People most at risk for suffering serious health consequences of toxoplasmosis are newly-infected pregnant women and anyone with a compromised immune system.

To learn more about Toxoplasma, its symptoms and other important information that you should know, visit this page.

Some microorganisms can cause big health problems when consumed in contaminated foods or beverages.

The world of foodborne microbes contains a mix of approximately 250 different types of bacteria, viruses, parasites, molds, and algae that are known to cause disease in humans and are therefore called foodborne pathogens. What they all have in common is that they are most often too small to be seen without a microscope, they have simpler structures and functions than higher plants and animals, and they are able to be cultured in laboratory settings with prescribed methods that aid in their identification.

The term foodborne pathogen loosely describes the microbes that are found in animals (in farm/zoo animals and pets) and in the environment (soil, water and air) that make people sick regardless of how they became infected.

Usually, infection happens by direct ingestion of a contaminated product, but it can also happen by contact with other individuals or contact with an animal or pet. Some foodborne microbes make people ill by forming toxins in foods that affect the gut or the neurological system. When an illness is caused by ingesting a toxin it becomes a poisonous agent and will generally make people sick faster than other foodborne pathogens which cause an infection.