14.2 – The Major Types of Foodborne Illness

Food Infection

According to the CDC, more than 250 different foodborne diseases have been identified.¹ Majority of these diseases are food infections, which means they are caused from food contaminated by microorganisms, such as bacteria, by microscopic animals called parasites, or by viruses. The infection then grows inside the body and becomes the source of symptoms. Food infections can be sporadic and often are not reported to physicians. However, occasional outbreaks occur that put communities, states, and provinces, or even entire nations at risk. For example, in 1994, an outbreak of the infection salmonellosis occurred in the United States due to contaminated ice cream. An estimated 224,000 people became ill. In 1988, contaminated clams resulted in an outbreak of hepatitis A in China, which affected about 300,000 people.²

^{1 Foodborne Illnesses and Germs. Centers for Disease Control and Prevention.https://www.cdc.gov/foodsafety/foodborne-germs.html . Updated February 16, 2018. Accessed June 8, 2019.}

^{2 Food Safety. World Health Organization. http://www.who.int/mediacentre/factsheets/fs399/en/. Updated June 2019. Accessed June 8, 2019.}

The Reproduction of Microorganisms

Bacteria, one of the most common agents of food infection, are single-celled microorganisms that are too small to be seen with the human eye. Microbes live, die, and reproduce, and like all living creatures, they depend on certain conditions to survive and thrive. In order to reproduce within the food, microorganisms require the following:

• Temperature: Between 41°F and 135°F*, which is called the danger zone, bacteria grow rapidly.
• Time: More than two hours in the danger zone.
• Water: High moisture content is helpful. Fresh fruits and vegetables have the highest moisture content.
• Oxygen: Most microorganisms need oxygen to grow and multiply, but a few are anaerobic and do not.
• Acidity and pH Level: Foods that have a low level of acidity (or a high pH level) provide an ideal environment since most microorganisms grow best around pH 7.0 and not many will grow below pH 4.0. Examples of higher pH foods include egg, meat, seafood, milk, and corn. Examples of low pH foods include citrus fruits, sauerkraut, tomatoes, and pineapples.
• Nutrient Content: Microorganisms need protein, starch, sugars, fats, and other compounds to grow. Typically high-protein foods are better for bacterial growth.

*ServSafe guidelines

Food Intoxication

Other kinds of foodborne illness are food intoxications, which are caused by natural toxins or harmful chemicals. These and other unspecified agents are major contributors to episodes of acute gastroenteritis and other kinds of foodborne illness.³ Like pathogens, toxins and chemicals can be introduced to food during cultivation, harvesting, processing, or distribution. Some toxins can lead to symptoms that are also common to food infection, such as abdominal cramping, while others can cause different kinds of symptoms and complications, some very severe. For example, mercury, which is sometimes found in fish, can cause neurological damage in infants and children. Exposure to cadmium can cause kidney damage, typically in elderly people.

^{3 Scallan E, Griffin PM, Angulo FJ, et al. Foodborne Illness Acquired in the United States—Unspecified Agents. Emerging Infectious Diseases. 2011;17(1):16-22. https://wwwnc.cdc.gov/eid/article/17/1/p2-1101_article. Accessed June 8, 2019.}