INPPAZ - PAHO - WHO
BIREME - PAHO - WHO

GuiaVETA
Guidelines of Surveillance System for Foodborne Diseases and Investigation of Outbreaks

FACTORS DETERMINING FOOD-BORNE DISEASES: CONTAMINATION, SURVIVAL AND MULTIPLICATION.

Among the determining factors in FBD are:

Faults in the cold chain of potentially dangerous food.

Storing food at lukewarm or room temperature (at an incubation temperature for bacterial agents).

Preparation of the food several hours or days before it is to be consumed with inadequate storage up to consumption.

Improper cooking or reheating of the food.

Poor personal hygiene among food handlers (may or may not have diseases or lesions).

Use of contaminated raw materials in preparing food that is usually served raw, or contaminated raw food coming in contact with another food already cooked.

Food prepared from contaminated raw materials that introduce microorganisms to the cooking and cause cross-contaminations.

Improper cleaning of kitchen utensils and equipment.

Environmental conditions that permit the growth of selected pathogens and inhibit competing microorganisms.

Food obtained from unreliable sources.

Improper storage practices.

Use of utensils or receptacles containing toxic materials.

Intentional or accidental addition of toxic chemicals to food.

Use of non-potable water.

Use of water from an unsafe supplementary source.

Water pollution through damage to the distribution network, construction or repair of pipes, cross-connections, floods, sewage overflows, improper siting of the tank, etc.

Contamination of hands of food handlers through carrying out repairs, cleaning, or collection of waste, etc.

Other Factors

Contamination factors

1. Toxic substances in the tissue of animals and plants: For example: marine toxins, fungi, mushrooms, some kind of pine .

2. Toxic substances added intentionally, accidentally, or incidentally: These may refer to pesticides, cyanide, cleaning residues, residues from packaging materials, residues from pipes.

3. Addition of excessive quantities of potentially toxic ingredients: An approved ingredient that is accidentally added in greater quantity, making the food unfit for consumption. For example, excessive nitrites in meats.

4. Raw products contaminated by animal or environmental pathogens: Processed carcasses, pieces of meat or poultry contaminated with pathogens when processing starts. For example: Salmonella and Campylobacter in poultry carcasses. As this frequently occurs in small populations, this factor is indicated only after confirmation by the laboratory that a common strain is present. Contaminated foods that are consumed without undergoing cooking, for example shellfish, raw milk, etc. Also, acquisition of food products from contaminated sources, for example shellfish, or products of recently fertilized areas.

5. Cross-contamination with raw animal ingredients: (E.g. kitchens, slaughterhouses, factories): This can occur in several ways. The raw food or its fluids touch or fall into food that is subsequently cooked. Food that is not subsequently processed or is stored in a utensil that was previously used for raw food of animal origin without having been cleaned. Food not treated with heat is handled by workers who may previously have handled raw food and did not wash hands afterwards. The equipment used for raw food is cleaned with wool, sponges, or another aids that are then used on surfaces in contact with food or on equipment that will then be used and not subsequently treated. Handlers without gloves for food that is ready for consumption. E.g. Staphylococcus.

6. Handling of food by an infected person or carrier: A person colonized by a pathogen and who does not wash hands after defecation and touches the implicated food directly with their hands.

Factors in survival or improper treatment to inactivate bacteria:

1.Insufficient time-temperature during the processes of cooking, heating and/or warming: (E.g. chicken or roast, pasteurization, sterilization, sauces, in-flight meals).

2. Inadequate acidification: When the quantity of acid added in the acidification process is inadequate for the elimination of pathogens that are present. (Ex. mayonnaise, canned tomatoes)

3. Improper thawing followed by improper cooking: When the center of the product remains frozen the thermal process does not eliminate pathogenic bacteria.

Factors that permit proliferation

1. Slow cooling: Caused when large masses or volumes of food are stored one on top the other, in large containers, with inadequate air circulation. Multiplication of spores and of other pathogens occurs.

2. Inadequate cold or hot storage: Through storage or display under refrigeration, through a malfunctioning refrigerator, or an improperly functioning `water bath`.

3. Extended storage under refrigeration: Permits the slow growth of psychrophilic bacteria.

4. Improper acidification: Produced through concentration of acid, ingredients with low levels of acid, the type of acid or insufficient contact time to eliminate the pathogens (E.g. Improper acidification or fermentation)

5. Improper reduction of water content: Caused by a too low concentration of salt, sugar, or other moisturizing substances to prevent pathogen multiplication in food that has not been refrigerated. These foods fall into the dangerous category. (E.g. Smoked or salted fish).

6. Improper thawing of frozen products: When frozen foods are thawed at room temperature or in a refrigerator for several days. Change and multiplication occur at the surface while the interior remains frozen.

7. Packaged in anaerobic/atmospherically modified conditions: This environment creates its own conditions for the growth of anaerobic or facultative bacteria in the food kept in hermetically sealed containers or in containers from which the gases have been evacuated or expelled through the addition of heavier gases. All anaerobic bacteria have low potential for oxide-reduction in initiating growth.