Foodborne Illness: Biological Hazards and Bacteria

What Causes Foodborne Illness?

• Foodborne illness is caused by risk factors to safety, security and sanitation.

Biological Hazards

• Foodborne biological hazards include organisms: bacteria, molds, viruses, and parasites.
• The seriousness of biological hazards varies greatly.
• It is difficult to avoid microorganisms because they are everywhere.
• Most biological hazards are inactivated/killed by adequate heating.
• Sufficient cooling regulates the numbers of biological hazards to a minimum.

Bacteria

• Bacteria is the number one cause of foodborne illness.
• Over 90% of foodborne illnesses are caused by bacteria.
• Only about 4% of identified bacteria are pathogenic (able to cause illnesses).
• The remaining 96% are benign (harmless).
• Some bacteria are helpful in the production of foods: cheese, yogurt, soy sauce, butter, sour cream, buttermilk, cured meats, sourdough bread, and fermented foods (pickles, beer, and sauerkraut).
• Beneficial and pathogenic bacteria are ubiquitous.
• Pathogenic bacteria cause 3 types of foodborne illnesses: infection, intoxication (poisoning), and toxin-mediated infection.

Food Infections

• About 80% of bacterial foodborne illnesses are due to food infections.
• These illnesses are caused by ingesting bacteria that grow in the host's intestine, replicate, and cause infection through their colonization.

Food Intoxication

• Foodborne illnesses can result from food intoxication or poisoning.
• Bacteria grow on the food and release toxins.
• These bacterial products, rather than the organisms themselves, cause illness after consumption.
• Certain plants/animals produce toxins.
• The most common food intoxicants originate from bacteria.

Toxin-Mediated Infection

• This type of foodborne illness occurs when bacteria enter the intestinal tract and then start to produce toxin within the intestine.

Molds

• Molds produce mycotoxins that can cause food intoxication.
• More than 300 mycotoxins have been identified, most of which don't present a significant food safety risk.
• Some mycotoxins are carcinogenic.
• Aflatoxin, a carcinogenic toxin made by Aspergillus flavus, is the most potent liver carcinogen known.
• Foods most likely to be infected with Aspergillus flavus: peanuts and grains.
• Aspergillus flavus has also been identified in corn, cottonseed, Brazil nuts, pistachios, spices, and figs.
• Patulin is a toxin produced by both Aspergillus and Penicillium that can contaminate fruits and cereals.
• Fumonisins are produced by Fusarium verticillioides and F. proliferatum, and are associated with corn.
• Molds are visible, exhibiting bloom on affected foods (unlike bacteria).
• Molds thrive at room temperature and need less moisture than bacteria.
• Foods susceptible to molds: breads, jams/jellies, and salty meats (ham, bacon, and salami).
• Black spots in the refrigerator are molds that can be cleaned with a solution of 1 tablespoon of baking soda dissolved in 1 quart of water.
• Musty-smelling dishcloths, sponges, and mops should be cleaned/replaced because such odors suggest mold.

Viruses

• Viruses are one of nature's simplest organisms.
• Unlike bacteria, which can exist independently, a virus needs a living cell in order to multiply.
• Microorganisms have been identified as causal agents in about 3-10% of foodborne illnesses.
• All foodborne viruses are transmitted via the oral-fecal route (contaminated feces to the mouth).
• Viruses may be passed from person to person/through carriers (flies, soiled diapers, water, and food).
• 2 common viruses that cause foodborne illnesses: hepatitis A virus and Norovirus.

Hepatitis A Virus

• Hepatitis A infection occurs most frequently after food is contaminated with fecal matter.
• Hepatitis B virus is transmitted through body fluids (not food).
• Another common source of hepatitis A is polluted shellfish beds and vegetable fields.
• Shellfish are a source of hepatitis A infection because they are eaten with their digestive tract intact.
• Another possible source of hepatitis A contamination is childcare centers, where diaper changing occurs.
• A vaccine is available that is 95% effective against the virus and provides protection for about 15 years.

Norovirus

• Norovirus, also known as Norwalk virus; it was named after the town in Ohio where the first identified outbreak occurred.
• Norovirus is the most common cause of gastroenteritis and responsible for up to 58% of all foodborne illnesses in the United States.
• It is the second most common viral infection after the common cold.

Parasites

• Parasites need a host to survive.
• They infect people in many parts of the world.
• 2 common foodborne parasites: roundworms and protozoa.

Roundworms

• Roundworm infections can result from eating undercooked pork and uncooked/undercooked fish.
• Trichinella spiralis roundworm causes trichinosis and is probably the most common parasite carried in food.
• Pork products are the primary source of infection.
• Heating pork to an internal temperature of 160 °F (71 °C) kills the T. spiralis larvae.
• Microwaving pork is not recommended because of its uneven heating.
• Herring worms, or Anisakis simplex, and cod worms, or Pseudoterranova decipiens, require that Japanese cooks inspect the fish for these tiny white worms while preparing sushi.

Protozoa

• Protozoa are single-celled animals that most frequently infect humans through contaminated water.
• About 4 of about 30 types of protozoa are related to food safety: Giardia, Toxoplasma gondii, Cryptosporidium, and Cyclospora.
• The most common protozoa is Giardia, but the most serious infection is due to Toxoplasma gondii.

Prions

• Prions are related to mad cow disease, or bovine spongiform encephalopathy (BSE).
• Prions are a type of transmissible spongiform encephalopathy (TSE) that riddles the brain with holes.
• TSE is a group of diseases that affect the brain, resulting in loss of coordination to convulsions and ultimately death.
• BSE is a disease affecting cattle.

Chemical Hazards

• Chemical hazards include any chemical substance hazardous to health.
• Harmful chemicals can come from additives (unintentional), plant toxins, animal toxins, or certain metals.
• Human error is usually responsible for chemical hazards.
• These errors usually involve kitchen cleaning supplies (bleach, soaps, and solvents).
• Contamination can be deliberate, such as the 2007 case when pet foods manufactured in China were intentionally spiked with melamine (industrial chemical) to artificially increase protein content.
• The incident resulted in animal deaths and highlighted the possibility of similar adulteration in the human food market.

Seafood Toxins

• Both fish and shellfish may harbor toxins that are unaffected by cooking, that can cause foodborne illness.
• Ciguatera fish poisoning is a toxin-related food poisoning, associated with tropical waters, that is not destroyed by heating.
• Excessive histamine accumulation in fish (especially tuna) can be detected by a slight tingling sensation in the mouth.
• Excessive histamine may result in histamine food poisoning (scombrotoxism).
• Other popular fish affected by histamine: mackerel, sardines, herrings, and mahi mahi.
• Histamine food poisoning is common in the US and occurs when fish have not been chilled immediately after being caught.
• Fish become toxic when bacteria (Morganella morganii) produce histamine while the fish are stored at incorrect temperatures.
• One of the most violent forms of seafood poisoning occurs with puffer fish when the liver, gonads, intestines, and/or skin are consumed.
• Puffer fish organs contain tetrodotoxin, which results in a mortality rate of 50% if ingested.
• Red tide is the result of the rapid growth of a reddish marine alga, usually during the summer in tropical waters.
• Shellfish (mollusks, oysters, and clams) and certain fish that consume red tide algae become poisonous and should not be eaten until the red tide has disappeared.

Physical Hazards

• Physical hazards that can harm the consumer's health when found in food/beverages include: hair (number-one hazard), glass, bone, metal (especially from opening cans), wood, stones, false fingernails, toothpicks, watches, jewelry, insect parts, staples from food boxes etc.
• People have needed emergency surgery after accidentally ingesting food containing a hidden single bristle from a wire grill-cleaning brush.