Module 4: Food Safety

Overview of Foodborne Illnesses

Foodborne diseases are defined as diseases associated with the ingestion of contaminated food.(1) Each year, foodborne illnesses cause 1 in 6 Americans (or 48 million Americans) to get sick, 128,000 to be hospitalized, and 3,000 to die.(2) Foodborne and waterborne illnesses together cause about 2.2 million deaths worldwide annually, 1.9 million of which are child deaths.(3) The World Health Organization (WHO) lists the major concerns for food safety:

Microbiological Hazards

In 1998, about 1.9 million children in developing countries, excluding China, died from diarrhea caused by microbiological agents from food or water. A 1995 study of foodborne diseases cited the cost of 3.3-12 million cases of foodborne illness associated with seven pathogens (in the United States) to be $6.5 to $35 billion.(4)

There are 31 foodborne pathogens known today. The majority (80%) of foodborne illnesses are due to unspecified agents. The leading causes (among known pathogens) of foodborne illness include:

Although norovirus usually only causes mild illness, it is the leading cause of foodborne illness because it affects so many people. Norovirus is highly contagious and can infect anyone. An individual can become infected with norovirus multiple times. This virus is the most common cause of gastroenteritis in the United States.(6)  

Table of Common Foodborne Pathogens(7)


Associated Foods

Symptoms and Potential Impact


Campylobacter jejuni

Contaminated water, raw or unpasteurized milk, and raw or undercooked meat, poultry, or shellfish.

Diarrhea (sometimes bloody), cramping, abdominal pain, and fever that appear 2 to 5 days after eating; may last 7 days. May spread to bloodstream and cause a life- threatening infection.

Cook meat and poultry to a safe minimum internal temperature; do not drink or consume unpasteurized milk or milk products; wash your hands after coming in contact with feces.

Clostridium botulinum

Improperly canned foods, garlic in oil, vacuum-packed and tightly wrapped food.

Bacteria produce a nerve toxin that causes illness, affecting the nervous system. Toxin affects the nervous system. Symptoms usually appear 18 to 36 hours, but can sometimes appear as few as 6 hours or as many as 10 days after eating; double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness. If untreated, these symptoms may progress causing muscle paralysis and even death.

Do not use damaged canned foods or canned foods showing signs of swelling, leakage, punctures, holes, fractures, extensive deep rusting, or crushing/denting severe enough to prevent normal stacking. 

Follow safety guidelines when home canning food. Boil home canned foods for 10 minutes before eating to ensure safety. (Note: Safe home canning guidelines may be obtained from State University or County Extension Office).

Clostridium perfringens

Meats, meat products and gravy Called "the cafeteria germ" because many outbreaks result from food left for long periods in steam tables or at room temperature.

Intense abdominal cramps nausea, and diarrhea may appear 6 to 24 hours after eating; usually last about 1 day, but for immune comprised individuals, symptoms may last 1 to 2 weeks. Complications and/or death can occur only very rarely.

Keep hot foods hot and cold foods cold! Once food is cooked, it should be held hot, at an internal temperature of 140 °F or above. Use a food thermometer to make sure. Discard all perishable foods left at room temperature longer than 2 hours; 1 hour in temperatures above 90 °F.


Soil, food, water, contaminated surfaces. Swallowing contaminated water, including that from recreational sources, (e.g., a swimming pool or lake); eating uncooked or contaminated food; placing a contaminated object in the mouth.

Dehydration, weight loss, stomach cramps or pain, fever, nausea, and vomiting; respiratory symptoms may also be present. Symptoms begin 2 to 10 days after becoming infected, and may last 1 to 2 weeks. Immune-comprised individuals may experience a more serious illness.

Wash your hands before and after handling raw meat products, and after changing diapers, going to the bathroom, or touching animals. Avoid water that might be contaminated. (Do not drink untreated water from shallow wells, lakes, rivers, springs, ponds, and streams.)

Escherichia coli

Uncooked beef (especially ground beef), unpasteurized milk and juices (e.g., “fresh” apple cider); contaminated raw fruits and vegetables, or water. Person to person contamination can also occur.

Severe diarrhea (often bloody diarrhea), abdominal cramps, and vomiting. Usually little or no fever. Can begin 2 to 8 days, but usually 3-4 days after consumption of contaminated food or water and last about 5 to 7 days depending on severity. Children under 5 are at greater risk of developing hemolytic uremic syndrome (HUS), which causes acute kidney failure.

Cook hamburgers and ground beef to a safe minimum internal temperature of 160°F. Drink only pasteurized milk, juice, or cider. Rinse fruits and vegetables under running tap water, especially those that will not be cooked. Wash your hands with warm water and soap after changing diapers, using the bathroom, handling pets or having any contact with feces.

Listeria monocytogenes

Ready-to-eat foods such as hot dogs, luncheon meats, cold cuts, fermented or dry sausage, and other deli-style meat and poultry. Also, soft cheeses made with unpasteurized milk. Smoked seafood and salads made in the store such as ham salad, chicken salad, or seafood salad.

Fever, muscle aches, and sometimes gastrointestinal symptoms such as nausea or diarrhea. If infection spreads to the nervous system, symptoms such as headache, stiff neck, confusion, loss of balance, or convulsions can occur .Those at risk (including pregnant women and newborns, older adults, and people with weakened immune systems) may later develop more serious illness; death can result from Listeria. Can cause severe problems with pregnancy, including miscarriage or death in newborns.

Cook raw meat, poultry and seafood to a safe minimum internal temperature; prevent cross contamination, separating ready to eat foods from raw eggs, and raw meat, poultry, seafood, and their juices; wash your hands before and after handling raw meat ,poultry, seafood and egg products. Those with a weakened immune system should avoid eating hot dogs, and deli meats, unless they are reheated to 165 ºF or steaming hot. Do not drink raw (unpasteurized) milk or foods that have unpasteurized milk in them, (e.g. soft cheeses). Do not eat deli salads made in store, such as ham, egg, tuna or seafood salad.

Salmonella(over 2300 types)

Raw or undercooked eggs, poultry, and meat; unpasteurized milk and juice; cheese and seafood; and contaminated fresh fruits and vegetables.

Diarrhea, fever, and abdominal cramps usually appear 12 to 72 hours after eating; may last 4 to 7 days. In people with weakened immune system, the infection may be more severe and lead to serious complications, including death.

Cook raw meat, poultry, and egg products to a safe temperature. Do not eat raw or undercooked eggs. Avoid consuming raw or unpasteurized milk or other dairy products. Produce should be thoroughly washed before consuming.

Shigella (over 30 types)

Person-to-person by fecal-oral route; fecal contamination of food and water. Most outbreaks result from food, especially salads, prepared and handled by workers using poor personal hygiene.

Disease referred to as "shigellosis" or bacillary dysentery. Diarrhea (watery or bloody) , fever, abdominal cramps; 1 to 2 days from ingestion of bacteria and usually resolves in 5 to 7 days

Hand washing is a very important step to prevent shigellosis. Always wash your hands with warm water and soap before handling food and after using the bathroom, changing diapers or having contact with an infected person.

Staphylococcus aureus

Commonly found on the skin and in the noses of up to 25% of healthy people and animals. Person-to-person through food from improper food handling. Multiply rapidly at room temperature to produce a toxin that causes illness. Contaminated milk and cheeses.

Severe nausea, abdominal cramps, vomiting, and diarrhea occur 30 minutes to 6 hours after eating; recovery from 1 to 3 days — longer if severe dehydration occurs.

Because the toxins produced by this bacterium are resistant to heat and cannot be destroyed by cooking, preventing the contamination of food before the toxin can be produced is important. Keep hot foods hot (over 140°F) and cold foods cold (40°F or under); wash your hands with warm water and soap and wash kitchen counters with hot water and soap before and after preparing food.

Vibrio vulnificus

Uncooked or raw seafood (fish or shellfish); oysters

In healthy persons symptom include diarrhea, stomach pain, and vomiting May result in a blood infection and death for those with a weakened immune systems particularly with underlying liver disease.

Do not eat raw oysters or other raw shellfish; cook shellfish (oysters, clams, mussels) thoroughly. Prevent cross-contamination by separating cooked seafood and other foods from raw seafood and its juices. Refrigerate cooked shellfish within two hours after cooking.

Estimated annual number of domestically acquired foodborne illnesses, hospitalizations, and deaths due to 31 pathogens and unspecified agents transmitted through food in the United States(8)

Foodborne Agents

Estimated annual number of illnesses 
(90% credible interval)


Estimated annual number of hospitalizations
(90% credible interval)


Estimated annual number of deaths 
(90% credible interval)


31 known pathogens

9.4 million 
(6.6–12.7 million)






Unspecified agents

38.4 million
(19.8–61.2 million)







47.8 million
(28.7–71.1 million)






Top five pathogens contributing to domestically acquired foodborne illnesses(9)


Estimated number of illnesses

90% Credible Interval






Salmonella, nontyphoidal




Clostridium perfringens




Campylobacter spp.




Staphylococcus aureus








Incidence of foodborne illnesses has increased in recent years, likely due to a variety of factors. First, changes in farm practices and a higher demand for meat and poultry increase the risk of foodborne illness. Additionally, extensive and interconnected food distribution systems facilitate the contamination of feed products. Furthermore, intensive animal husbandry techniques currently employed have triggered the emergence of new zoonotic diseases.

Chemical Hazards

Chemical toxins can be found in foods that contain natural toxicants, including mycotoxins (produced by microfungi). Mycoses are diseases caused by the growth of fungi on animal hosts, while mycotoxicoses are those caused by dietary, respiratory, or dermal exposure to toxic fungal metabolies. Mycoses range from the relatively mild athlete’s foot to the lethal aspergillosis, and can be acquired via inhalation of spores or from a growth on the skin or gastrointestinal tract. Most mycotoxicoses, on the other hand, result from eating contaminated food.(10)

Furthermore, environmental toxins, such as mercury and lead, can have dangerous health consequences when ingested. Today, mercury poisoning is generally caused by the consumption of fish. Mercury poisoning can lead to many neural diseases, including acrodynia (pink disease), Hunter-Russell syndrome, and Minamata disease. Lead, another heavy metal, can also interfere with the nervous system, as well as with the heart, bones, intestines, kidneys, and reproductive system.(11) Lead can enter the body through multiple routes, including inhaling lead dust in the air, ingesting lead paint, and drinking contaminated water. No amount of lead in the body is safe.

The FDA also regulates the following chemical toxins:

New Technologies

Genetically modified organisms (GMOs) are organisms whose DNA has been altered through genetic engineering. Genetically modified organisms and foods were originally developed to improve crop resistance to plant diseases.(17) For example, plants that have the gene for toxin production by the bacterium Bacillus thuringiensis (BT) require lower quantities of insecticide spray. This BT toxin is safe for human consumption. Today, organisms are modified for more traits, including pest resistance, herbicide tolerance (so that weeds die but GMO crops do not), disease resistance, cold tolerance, drought tolerance, and higher nutrient levels. Rice illustrates one attempt to use genetic engineering to increase nutritional benefit. A staple food for many nations, rice does not contain many nutrients. Researchers have created a “golden” strain of rice that contains a high amount of beta-carotene (vitamin A).(18) Therefore, proponents of GMOs argue that GM foods may be the key to alleviating malnutrition and increasing food security.

GM foods traded internationally have passed risk assessments, and are thus generally safe to consume. GM foods must pass Codex Alimentarius standards (or the Codex system), which are food standards set by a joint FAO/WHO body. The Codex system was implemented in 1963, and deals with all government-regulated characteristics of certain commodities. Furthermore, the Cartagena Protocol on Biosafety (CPB) is an environmental treaty that regulates transboundary movements of living GMOs.

Debates on the health effects of GM foods are primarily concerned with allergenicity. Many children have allergies to multiple foods, and experts worry that introducing a gene into a plant or animal may introduce a new allergen or cause allergic reactions. To avoid allergic outbreaks, extensive testing is required before selling GM foods on the market. While there are other worries about more possible health detriments of GM foods, current evidence does not suggest any other health concerns.(19)

Go To Module 5: Food Safety Precautions >>


(1) Geneva. World Health Organization. Department of Food Safety, Zoonoses and Foodborne Diseases Sustainable Development and Healthy Environments. WHO Consultation to Develop a Strategy to Estimate the Global Burden of Foodborne Diseases. France: WHO, 2006. Print.

(2) CDC. "CDC Estimates of Foodborne Illness in the United States." Centers for Disease Control and Prevention, 07 Feb. 2012. Web. 22 May 2012.

(3) "Food Safety." World Health Organization. Web. 22 May 2012.

(4) "General Information Related to Microbiological Risks in Food." World Health Organization. Web. 22 May 2012.

(5) CDC. "CDC Estimates of Foodborne Illness in the United States." Centers for Disease Control and Prevention, 07 Feb. 2012. Web. 22 May 2012.

(6) CDC. "Norovirus." Centers for Disease Control and Prevention, 12 Apr. 2012. Web. 22 May 2012.

(7) "Foodborne Illness: What Consumers Need to Know." USDA Food Safety and Inspection Service, 24 May 2011. Web. 05 June 2012.

(8) CDC. "CDC Estimates of Foodborne Illness in the United States." Centers for Disease Control and Prevention, 07 Feb. 2012. Web. 22 May 2012.

(9) Ibid.

(10) Bennett JW, Klich M. Mycotoxins. Clinical Microbiol Rev. 2003;16:497–516. doi: 10.1128/CMR.16.3.497-516.2003

(11) Mayo Clinic Staff. "Lead Poisoning." Mayo Foundation for Medical Education and Research, 12 Mar. 2011. Web. 22 May 2012.

(12) Robin, Lauren P. Acrylamide, Furan, and the FDA. Rep. Ed. Sebastian Cianci. Target Group, 2007. Print.

(13) FDA. "Dioxin Analysis Results/Exposure Estimates." US Food and Drug Administration, Mar. 2004. Web. 23 May 2012.

(14) FDA. "Ethyl Carbamate Preventative Action Manual." US Food and Drug Administration, 24 July 2011. Web. 23 May 2012.

(15) Robin, Lauren P. Acrylamide, Furan, and the FDA. Rep. Ed. Sebastian Cianci. Target Group, 2007. Print.

(16) FDA. "Contaminants & Adulteration Food Safety Food Contaminants & Adulteration Chemical Contaminants Melamine - Interim Safety and Risk Assessment of Melamine and Its Analogues in Food for Humans." US Food and Drug Administration, 3 Oct. 2003. Web. 23 May 2012.

(17) "20 Questions on Genetically Modified Foods." World Health Organization. Web. 22 May 2012.

(18) Whitman, Deborah B. "Genetically Modified Foods: Harmful or Helpful?" ProQuest, Apr. 2000. Web. 22 May 2012.

(19) Ibid.