Types of Food Poisoning: Bacteria, Viruses, & Parasites

On this page
Food Poisoning Information
Find answers:

Poison Control Center 24/7

Foodborne Illness causing Pathogens

Food poisoning can be caused by a variety of different pathogens. The three most common are viruses, bacteria, and parasites. While the term “food poisoning” is commonly used to describe the negative effects after ingesting food that has been contaminated by bacteria or viruses, this is actually a misnomer. Foodborne illness more accurately describes what happens when people become ill from eating something they have eaten. There is a distinction between food poisoning and foodborne illness.


The Norwalk virus is the most common cause foodborne illness in the US. Other common viruses are hepatitis A, and rotavirus. Hepatitis E has the potential to be transmitted via food, but it’s very rare.

Foodborne illness-causing viruses are commonly spread through fecal-oral contamination. This means that the virus lives in the stool of an infected person, and is then transmitted to another person when they ingest contaminated food. This can occur most often through food workers who may not practice proper hygiene while handling food or surfaces that food comes in contact with.

Symptoms of foodborne illness from viruses are often short-term and include vomiting, diarrhea, nausea, fever, and abdominal cramps. However, some people can experience symptoms such as jaundice which is a yellowing of the skin and eyes, and darkening of urine color. Some viruses like Rotavirus only cause symptoms for one to seven days but other viruses like Hepatitis A can cause symptoms for several weeks.


Bacteria is another common cause of foodborne illness and can be transmitted by eating undercooked or raw foods, as well as cross-contamination between contaminated surfaces and other foods. Some of the most common types of bacteria that causes food poisoning include Campylobacter, Salmonella, Clostridium perfringens (commonly referred to as C. perfringens), Escherichia coli 0157:H7 (commonly referred to as E.coil or EHEC) and Listeria monocytogenes (commonly referred to as Lm.)

Symptoms of foodborne illness resulting from bacterial contamination can vary but often include diarrhea, fever, vomiting, abdominal pain, and cramps. Bacterial pathogens can cause more severe symptoms for people with weakened immune systems. These people include children, the elderly, and individuals who are already ill or taking medications that suppress their immune system.

The CDC estimates that every year 1 in 6 Americans (or 48 million people) get sick from foodborne illness, 128,000 are hospitalized due to these illnesses and 3,000 die.

Common symptoms of foodbrone illness include:


A third common type of pathogen that can cause foodborne illness is parasites. These organisms are usually transmitted by eating raw or undercooked meat, fish, and shellfish. Common types of parasites include Giardia lamblia (commonly referred to as Giardia), Cryptosporidium, Toxoplasma gondii (commonly referred to as T. gondii) and Trichinella spiralis (commonly referred to as Trichinella).

Symptoms of foodborne illness from parasites include diarrhea, stomach cramps, nausea, vomiting, fever or headache. In some cases abdominal pain can occur along with a lack of appetite and weight loss.

Symptoms of food poisoning can vary depending on the type of microbe that causes it. Symptoms can begin within a few hours after ingesting contaminated food, and in some cases can take days or weeks to appear. Most healthy people who are infected will recover without treatment and experience reduced symptoms within a week, but some people will continue to experience symptoms for several weeks. In some cases, a serious condition known as Hemolytic Uremic Syndrome can develop which causes a person’s kidneys to stop working properly.

Seek medical attention

If you have a fever over 102 degrees, bloody stool, or other severe symptoms you should seek medical attention immediately.

Legal Assistance

If you are a victim of food poisoning caused by someone else’s negligence you may be entitled to financial compensation through a food poisoning lawsuit.

Food Poisoning Information
Find answers:

Poison Control Center 24/7