What is Foodborne Illness?

Foodborne illnesses have historically been one of the most prominent causes of illness and death. However, thanks to advances in sanitation, refrigeration, and medicine, foodborne illness is not nearly the threat it once was. Nevertheless, it is still common. In the United States, there are roughly 3 million cases of foodborne illness diagnosed per year, leading to 128,000 hospitalizations and 3,000 deaths.

Foodborne illness is defined as any illness caused by ingesting food or beverages contaminated with harmful bacteria, viruses, molds, parasites, or toxins. The five most common foodborne illnesses, according to the Centers for Disease Control, are the norovirus, the Hepatitis A virus, Salmonella bacteria, Shigella bacteria, and E. Coli bacteria. Together, these foodborne pathogens are known as The Big 5. But answering the question, "What is foodborne illness?" requires a deeper dive into the causes, the symptoms, and a few detailed examples.

What are the Causes of Foodborne Illness?

The causes of foodborne illness are often separated into three distinct categories. These include physical hazards (e.g. food contaminated with broken glass), chemical hazards (e.g. toxins in certain mushrooms), and biological hazards (e.g. bacterial contamination). However, biological hazards are by far the most common of three.

Biological foodborne illness has long been a threat to humans. In fact, the very reason we cook our food, and the reason we season it with spices, is to kill foodborne pathogens. However, even in the age of modern medicine, contaminated food is still a threat. Below is a list of some of the most common causes of foodborne illness.

• Bacteria: Bacteria like E. Coli and salmonella are the most common cause of foodborne illness. Bacteria are single-celled organisms with no nucleus. They grow best in warm, wet environments where food is available. Unrefrigerated food makes a perfect growth medium. However, below 41 degrees Fahrenheit and in environments when water is not available, bacteria cannot easily grow on food. This explains the helpful effects of refrigeration (to lower the temperature) and salting our food (which ties up water molecules).
• Molds: Molds are multicellular fungi that reproduce by releasing thousands of microscopic spores. Molds often send roots deep into the food, with only the white or green spores being visible on the surface. Molds prefer dark, damp environments and, although they prefer warm temperatures, they can often grow inside refrigerated environments as well. Although they are not nearly as threatening as bacteria, some molds release toxins that can cause foodborne illness.
• Viruses: Viruses are tiny, microscopic organisms that contain either DNA or RNA. They hijack human cells, using the cells to make copies that are then released into the rest of the body. Unlike the flu, which is a respiratory virus that is inhaled and reproduced in our lungs, foodborne viruses affect the intestinal tract. One of the most common and most contagious of these is norovirus. However, viruses do not grow on food like bacteria or mold. They simply use food as a vehicle (a nonliving source of pathogens) for transmission. They can only reproduce inside of human cells.
• Parasites: Parasites like giardia, roundworms, and tapeworms are much larger than viruses. However, they are similar in that they can only multiply inside humans or other animals. They do not grow atop our food in the way that bacteria and mold do. Rather, they use contaminated food as a vehicle for transmission. Parasites are often spread through fecal matter and can be significantly limited with proper sanitation and simple handwashing.

What are the Most Common Symptoms of a Foodborne Illness?

Although the causes of foodborne illness can vary wildly, the symptoms of foodborne illness are often remarkably consistent. The question "What are the most common symptoms of a foodborne illness?" typically requires three distinct answers.

• Diarrhea: Diarrhea is defined as the sudden release of loose, watery feces. It is one of the body's natural responses to contaminated food, as the body attempts to get rid of the pathogen as quickly as possible. However, diarrhea can often lead to discomfort, malnutrition, and severe dehydration.
• Abdominal Pain: Abdominal pain is often referred to as 'belly pain' or simply as an 'upset stomach.' The pain is often due to a disturbed microbiome in one's intestines. This can lead to abnormal breakdown of foods, gas buildup, and other problems.
• Vomiting: Vomiting is defined as the sudden ejection of stomach matter through the mouth. This is another of the human body's natural rejections to suspected contamination. The body attempts to reject the contaminated food as quickly as possible. Although short-lived, vomiting can be a sign of a serious infection (such as norovirus). Like diarrhea, it can also lead to malnutrition and dehydration.

Foodborne Illness Types

The types of foodborne illness can be broken down in several ways. Two of the most common types are food poisoning and food infection. Both are described in more detail below.

Food Poisoning

Food poisoning is a term use colloquially to refer to any number of foodborne illnesses. But food poisoning is more formally defined as any illness caused by ingesting food containing preformed microbial toxins. In reality, the precise causes of food poisoning often goes undiagnosed. Symptoms like diarrhea, abdominal pain, and vomiting last only a day or two in most cases. For example, diagnosing what bacteria causes food poisoning would typically require laboratory analysis.

Food Infection

The term 'food infection' specifically refers to the biological contamination of food. This type of foodborne illness refers specifically to that which is caused by bacteria, viruses, molds, and parasites. It is by far the most common cause of foodborne illness. In fact, The Big 5 foodborne infections, as classified by the Centers for Disease Control, are all examples of food infection. The norovirus and Hepatitis A are both viruses. Salmonella, Shigella, and E. coli are all bacteria. Food infection is different from the flu, which is a respiratory virus that travels through the air and reproduces slowly within the cells inside the human respiratory tract. Food infections are caused an active microbial infection from eating a pathogen-containing food.

Foodborne Illness Examples

There are many types of foodborne illness. Below are the five most common foodborne illness examples according to the United States CDC. A brief description of each can be found below.

• Norovirus: Norovirus is the leading cause of foodborne illness in the United States. It is transmitted from person to person, using contaminated food as a vehicle for transmission. It is highly contagious and can be lethal in small children.
• Hepatitis A: Hepatitis A is a virus that is common in developing countries and in children in the United States. It is often passed through contaminated food, often due to poor handwashing practices. Symptoms of the virus often take 3-4 weeks to become visible.
• Salmonella: Salmonella is a type of bacteria which causes the disease commonly referred to as typhoid. Symptoms include headaches, fever, constipation or diarrhea, and red spots on the infected person's trunk. The organism is typically spread by sharing food or drink with an infected individual.
• Shigella: Shigella is a type of bacteria that causes fever, abdominal cramps, chills, vomiting, and bloody diarrhea. It is often spread through contaminated foods (such as salads) that have been prepared by infected individuals using unsanitary practices. It most often occurs in overcrowded environments like prisons or day care centers.
• E. Coli: There are many strains of E. Coli bacteria, many of which are harmless. However, harmful E. Coli is a major cause of foodborne illness; the pathogen is often found in raw meats or raw milk. Symptoms include nausea, diarrhea, and abdominal cramps. Symptoms usually begin 2-5 days after ingestion and last roughly one week.