Biological Contamination

Safe Facilities    

Biology is the science of studying living beings such as bacteria, fungi, plants and animals and non-living being such as viruses. Biological contaminants of food are harmful and hazardous substances of biological origin in the food that can cause foodborne illness when they are consumed. Biological contaminants could be microorganisms, so small that only can be seen by a microscope such as bacteria and versus, or could be large such as some parasites. A pathogen commonly called a germ is a disease-causing microorganism. There are also some biological toxins that are associated with certain plants, mushrooms, fish and shellfish that can cause foodborne illnesses. To prevent the outbreak of foodborne illnesses, it is crucial for food service professionals to understand all aspects of biological contaminants from how they grow and reproduce to how they contaminate food and infect humans. Here bacteria, viruses, parasites, fungi and biological toxins will be explained and examples will be provided.

1. Bacteria

BacteriaBacteria are single-cell microorganisms that are almost everywhere, in air, water, soil, and in and on humans, animals, and plants. They can also survive the harshest of environments from very cold to very hot. Some are beneficial to us and some make us sick or are fatal. They can be seen only by a microscope and can not be tasted or smelled They are of the greatest concern to food service professionals so all the time necessary should be spent to combat them by understanding what condition favors the growth of pathogenic bacteria and what conditions eliminate or reduce them to a safe level. The right condition for the growth of bacteria and other foodborne microorganisms is remembered by acronym FAT TOM
Food - Like other living beings bacteria need energy to live. Poultry ,eggs, dairy products, meat, fish, shellfish, baked potatoes and other TCS food are ideal sources of energy for their growth.

Acidity - Bacteria grow best in food that is lightly acidic to neutral.

Temperature - The Temperature Danger Zone is the temperature between 41 F and 135 F that favors the growth of bacteria. Food service professionals must always remember this danger zone and limit the time TCS food spends in this zone.

Time - In a favorable condition, such as TCS foods that stay long in temperature danger zone, a bacteria can grow to over 10 billions in 10 hours. This shows the importance of controlling the time TCS food kept in the temperature danger zone. The more time, the more numbers and more chance of growing to a number that makes food unsafe.

Oxygen - Some bacteria need oxygen for their growth (aerobic) and some do not (anaerobic) and some can grow with or without oxygen (facultive).

Moisture - Moisture favors the growth of bacteria.

The FDA has particularly identified three bacteria that are highly contagious and can cause severe illnesses. Food handlers diagnosed with illnesses caused by these bacteria must NEVER work in a foodservice operation while they are sick. Eating small amount of these bacteria can make a person sick.
1. Salmonella Typhi
- Lives only in humans. Ready-to-eat food and beverages are linked with this bacteria.
- Preventive measures are washing hands and cooking food to minimum internal temperatures.
2. Shigella spp
- Found in human waste and flies, and unwashed hands can transfer it to food;
- Food linked with this bacteria are food that are contaminated by hands such as salads containing TCS food (potato, tuna, shrimp, macaroni, and chicken) and food that has been in contact with contaminated water, such as produce.
- Preventive measures are washing hands and controlling flies inside and outside of the operation.
3. Enterohemoregic and shiga toxin-producing Escherichia coli (E .coli)
- Found in infected people and intestines of cattle and produces toxins (poisons) in human intestines that cause the illness.
- It is linked with ground beef (raw and uncooked) and contaminated produce.
- Preventing measures are:
- Prevent cross-contamination between raw meat and ready-to-eat-meat;
- Purchase produce from approved , reputable suppliers; and
- Cook food, especially ground beef, to minimum internal temperatures.

2. Viruses

VirusLiving beings are made of cells, consume energy and reproduce. Viruses are not made of cells, do not need energy to exist and only can reproduce using other living cells like human cells. So for them to make copy of themselves they must use living cells like human or animal cells. They can not grow and divide on food, but they can be transmitted to a human body by food or water or contaminated surfaces. People can also transmit them to food and and to other people, in addition to food-contact surfaces. They are able to survive cooking and freezing temperatures. It can be transmitted through vomit particles. Practicing good personal hygiene by food handlers, washing, cleaning and sanitizing food-contact surfaces and a quick vomit cleanup and removal from the site are important measures for stopping the spread of viruses.

The FDA has particularly identified two highly contagious viruses that can cause severe illnesses. The staff who have been diagnosed with these viruses must be excluded from the operation. Eating small amount of these viruses can make a person sick.
1. Hepatitis A
- The source is human feces and often is transferred by unwashed fingers to food and equipment.
- The virus also found in water, ready-to-eat food and shellfish from contaminated water. Cooking does not destroy hepatitis A.
- The prevention measures are washing hands, not touching ready-to-eat food with bare-hand, and purchasing shellfish from a safe source. Exclude staff who have jaundice from the operation.
- An infected person can carry the virus for weeks without showing any symptoms.
2. Norovirus
- The source is human feces and often is transferred by unwashed fingers to food and equipment.
- The viruses are linked with ready-to-eat food and shellfish from contaminated water.
- Preventive measures are excluding staff with diarrhea and vomiting from the operation, washing hands, not touching ready-to-eat food with bare-hand, and purchasing shellfish from a safe source.

3. Parasites

parasiteMost living beings are able to get their own food and reproduce independently. Parasites like roundworm and protozoan on the other hand need to use other living beings as a host to survive and reproduce. They use animals such as pigs, seafood and wild game and plants as a host and can be transmitted to humans. Produce and other food processed with contaminated water can also contain parasites. Cooking and freezing can destroy them. The best way to prevent contamination by parasites is to purchase food from approved and reputable suppliers. Also make sure the food is cooked to its required minimum internal temperature. If serving fish that is undercooked or raw, make sure the manufacturer properly has frozen the fish.

4. Fungi

FungiMolds, yeasts and mushrooms belong to a kingdom of life called Fungi and can be found in air, land, water, animals, plants and in some popular foods. Some are made of one cell and some are made of many cells. Some molds produce a toxin called aflatoxins. They can cause foodborne illness. Molds and yeasts grow best in acidic, sweet environment with low water activity such as jam and jellies. Molds spoil food so all moldy food should be thrown away unless the mold is the part of the food like in cheeses Gorgonzola, Bleu and Brie. Molds are not destroyed by freezing. Yeasts consume food and produce alcohol and carbon dioxide. Some mushrooms produce toxins that cause foodborne illness. The best prevention is to buy mushrooms from an approved and reputable suppliers.

5. Biological Toxins (Poisons)

Some small fish and some shellfish eat algae that contain a toxin called ciguatera toxin. Some predatory fish such as snapper, amberjack, barracuda and grouper eat these small fish and become contaminated with the ciguatera toxin. Shellfish such as mussels, clams, scallops become contaminated by eating the algae. Toxins are also natural part of some fish like pufferfish. When time-temperature abused, bacteria in some fish like tuna, bonito, bluefish, mackerel, mahimahi, produce a toxin called histamine. In addition some toxins are natural part of some plants and fungi. Cooking and freezing do not destroy biological toxins and these toxins can give rise to many illnesses whose symptoms will be experienced within minutes of eating the toxin . To prevent foodborne illness from using plants, mushrooms, and seafood, we must purchase these foods from approved and reputable suppliers and prevent time-temperature abuse when handling raw fish..