FOOD POISONING AND FOOD BORNE DISEASES

"Food poisoning" is a general name given to illnesses contracted by consuming contaminated food or water. The microorganisms responsible for illness are bacteria, viruses and fungi, commonly called "germs: or "bugs". But illness can also be caused by chemical contaminants (such as heavy metals), toxins produced by the growth of some microorganisms (eg. Staphylococci bacteria) and by a variety of organic substances that may be present naturally in foods (such as certain mushrooms and some seafood).

Generally food poisoning results from contamination of food and the subsequent growth of food poisoning microorganisms. Food poisoning outbreaks are often recognised by the sudden onset of illness within a short period of time among many individuals who have eaten , drunk one or more foods in common. Single cases are difficult to identify unless, as in Botulism for example, there are distinct symptoms. Food poisoning may be one of the most common causes of acute illness; yet cases and outbreaks are generally under-recognised and underreported

Reasons for Food Poisoning

1. Inadequate cooling/refrigeration, food left at room temperature.
2. Too long between preparation and consumption.
3. Inadequate reheating.
4. Inadequate cooking.
5. Cross-contamination from raw to high risk/ ready to eat foods.
6. Infected food handlers.
7. Inadequate hot holding temperatures.
8. Inadequate hand washing.
9. Contaminated raw foods and ingredients.
10. Improper cleaning of equipment and utensils.

Prevention from Food Poisoning

In most cases of food poisoning a chain of events takes place, and if we are to reduce the incidence of illness, this chain must be broken.

Food Poisoning Chain

There are three main ways of breaking the food poisoning chain:
* Protecting food from contamination.
* Preventing any bacteria present in the food from multiplying.
* Destroying those bacteria that are present in the food.

Protecting food from contamination by:
* Inspecting all food and washing fruit and vegetables before preparation.
* Separating raw and high risk/ready to eat foods at all stages of preparation, storage, display and distribution.
* The same equipment, utensils and working surfaces must not be used to handle raw and high risk/ready to eat foods.
* Only handling food when unavoidable. Gloves, tongs and other utensils, plates and trays should be used in preference to hands, (but must be washed or changed frequently).
* Keeping food covered as much as possible.
* Preventing insects, animals and birds from entering food rooms.
* Not using unsuitable, defective, or dirty equipment.
* Using good personal hygiene practices - always.
* Not coughing or sneezing over or around food.
* Not handling the food contact surfaces of crockery, cutlery or utensils.
* All food handlers wearing suitable protective clothing.
* Using the correct cleaning procedures.
* Promptly removing unfit or waste food and refuse from food areas.

Preventing any bacteria within food from multiplying by:
* Keeping high risk foods at temperatures that inhibit the growth of bacteria (ie. out of the danger zone). Food should be kept below 4°C in a refrigerated unit, or above 70°C in a suitable warming unit. * Ensuring that during preparation, food is in the danger zone for as short a time as possible. High risk foods must not be left sitting out at room temperature.
* Using suitable preservatives such as salt and sugar.
* Using various packing methods like gas flushing or vacuum packing.
* Not allowing dried foods to absorb moisture.

Destroying those Bacteria within food by:
* Adequately cooking food, ensuring that a minimum internal cooking temperature of 80°C is reached.
* Heat processing such as pasteurisation, sterilisation or canning.

A combination of a suitable temperature and sufficient time is always required to destroy bacteria. The time and temperature required will depend on the particular organism, (eg. spores of Clostridium perfringens are much more heat resistant than Salmonella bacteria).

Personal Hygiene

Good personal hygiene reduces the chance of contamination of food.
* Hands must be washed before and after handling food.
* If unwell, do not handle food until cleared by a doctor.
* The hair, nose and mouth must not be touched during food preparation.
* Suitable light coloured protective clothing should be worn.
* Cuts and abrasions should be covered with waterproof bandages and if on the hands suitable gloves worn.
* Rings and other jewellery should not be worn as they can harbour dirt and bacteria and could themselves fall into the food being prepared.

Food Spoilage

Food decays or goes off, due to the microorganisms that always exist in food;- they are not necessarily the bacteria that cause food poisoning. The signs that food is spoiling are:
* Odour-" off odours" are smells (sometimes like rotten eggs) that are produced when bacteria break down the protein in food, (usually fatty foods). This process is called putrefaction.
* Taints due to flavour change may also occur.
* Sliminess - Food becomes slimy as the bacterial population grows.
* Moulds may also form slimy whiskers.
* Discolouration - Foods can become discoloured by microbial growth.
* Some moulds have coloured spores that give the food a distinctive colour, for example, black pin mould on bread, or blue and green mould on citrus fruit and cheese.
* Souring - Foods go sour when certain bacteria produce acids. A common example is when milk sours from the production of lactic acid.
* Gas - Bacteria and yeasts. often produce gaseous byproducts that can affect food. You may have noticed meat becoming spongy, or packages and cans swelling or having a popping or fizzing sound on opening.

Microorganisms

Microorganisms are often called bugs. This is a little too simple however and food handlers should know a little more about them. They differ from one another in appearance and activity, and looking at those found in food as a whole we find that provided suitable nutrients are available growth occurs:
* At temperatures between -7 to around 70°C.
* Over a pH range from 0 to 11.
* In the presence or absence of oxygen.
* At water activities above about 0.6.

Spoilage of any particular food will be by those organisms most suited to the conditions in and around that food.

The three main groups of concern are:
* Bacteria
* Viruses
* Fungi (yeasts / moulds)

Bacteria

Bacteria are microscopic organisms that are found everywhere - in air, soil, water, plants, animals and the human body. You can't see, taste or smell most bacteria. If the environmental conditions are favourable, just about any material will support the growth of some bacteria. Most bacteria are harmless and some are helpful, like those that change milk into cheese or yoghurt. But others cause food spoilage and some known as pathogens are harmful and can cause illness and sometimes death. The number of bacteria present in food may be used to determine whether or not the food has been handled correctly. The diseases that are spread by bacteria that enter the body in food, can multiply at an amazing rate when they are provided with warmth and moisture, (especially at room temperature). Our food can become an ideal home for them.

Clean food can be contaminated by bacteria from four main sources:
* The people present in the workplace and their clothing.
* Other food that is already contaminated.
* Dirty kitchen or work premises and equipment.
* Insects and vermin.

Sometimes, harmful bacteria pass directly from the source to high risk food, but usually they rely on other things to transfer them to food. These things are called Vehicles. Indirect contamination using an intermediate vehicle is the most common, eg.- the movement of bacteria from the intestine of a food handler to food via their hands, after using the toilet.

Where contamination is passed from raw food to high risk food via for example, a cutting board, this is known as Cross Contamination. The path that bacteria use to move from the source to the food, is known as the Route.

Viruses

Viruses are organisms much smaller than bacteria. In their pre-infective stage they are just like a chemical with none of the requirements for life, but once in a living cell they take over and begin to multiply. They can grow only in living tissue, but can be carried in food from one person to another.

Fungi

Yeasts

Yeasts are single cell organisms much larger than bacteria and can be found in the soil, on plants and on the skin and body of man. They multiply by forming offspring as buds which grow and then detach themselves.

Some can produce disease, some cause skin infections in man and others cause diseases in plants. Some yeasts spoil food, but beneficial uses are in the making of beer, wine and bread.

Moulds

Moulds grow as single cell filaments that can branch together making a strongly knit structure like a mat, that can often be seen with the naked eye. Usually they look fluffy, being a familiar sight on foods like jam, cheese and bread. They multiply by producing clusters of dry spores which are blown by the air like seeds. Many moulds spoil food and a few can cause disease in plants and man, but beneficial uses are in the ripening of cheeses and production of antibiotics.

Growth of Microorganisms

There are certain environmental conditions that must be met for microorganisms to grow and multiply and when these conditions exist they can very quickly increase in number.

These conditions are:
* Time
* Food
* Temperature
* pH
* Water
* Oxygen

Anything less than optimum conditions will lead to a slowing down or a stopping of growth and then possibly their death.

* Time: Time is needed for the organism to grow and reach maturity. In most cases we try to prevent an organism from maturing by making its environment unsuitable for growth.
* Food: All organisms need food for growth and energy.
* Temperature: Each microorganism has an optimum temperature where it grows most rapidly and a maximum and minimum temperature at which it will grow. Outside this range it will grow very slowly, or not at all.
* pH: The numbers on the pH scale, as shown in the following diagram, indicate the acidity or alkalinity of a fluid. Microorganisms can grow and multiply only within a certain pH range.

Most prefer to live in a neutral environment around pH 7. A small group of microorganisms prefer an acid environment and do not grow in the neutral range. Low pH generally inhibits microbial growth. Yeasts and moulds are the most capable of growth 'at low pH. Other acid-producing bacteria such as lactic acid bacteria also predominate at low pH.

* Water: Without water, Dehydration (loss of moisture) occurs and the life and growth processes of microorganisms slow down and may stop. The microorganisms might not be destroyed however. The use of salt or syrups (sugar) in various foods is a way of activating this process. These salts and sugars are crystals that compete with the microorganisms for the available water that they need for survival.

It is now generally accepted that the water requirements of microorganisms should be defined in terms of the water activity (aw) in the environment. This is a measure of the availability of water to microorganisms for metabolism (the processes of life). The (aw of pure water is 1.00, - a 22% salt solution has an  (aw of 0.86 and a saturated salt solution is 0.75. The (aw value for most fresh foods is above 0.99.

* Oxygen: Microorganisms respire. That is, they get energy by breaking down chemicals, usually ~ugars, inside the cell. Aerobic organisms must use oxygen obtained from their environment (usually air) before they can produce energy for life and growth. Anaerobic organisms can produce this energy only in the absence of oxygen. Facultative organisms can respire in either aerobic or anaerobic conditions.

Control of Microorganisms

Control of microorganisms is needed to prevent:
* The spread of disease and infection.
* The spoilage of foodstuffs.
* Contamination of food.

The most common ways of killing microorganisms are by heat and by chemicals. Other less common means include, irradiation, ultrasonic sound and very high pressure. Some bacteria, and almost all virus, yeast and mould cells are killed by a temperature of 60°C for 10 to 20 minutes.

east and mould spores, and most other bacteria are destroyed at temperatures be~een 70 - 100°C for 5 to 10 minutes exposure. Bacterial spores however, are very difficult to destroy. Some for example, need at least 10 minutes at 100 to 120°C.

The following terms' are commonly used in cleaning:
* Sterilisation- The process of destroying or removing all microbial life.
* Disinfection- The killing of disease causing bacteria as well as other living microorganisms, but not usually bacterial spores. Disinfection does not necessarily kill all microorganisms, but reduces them to a level not usually harmful to health. In this group are the fungicides (kills fungi), bactericides (kills bacteria) and virucides (kills viruses).
* Sanitising - A term meaning that an article or surface is visibly clean and is free of disease producing organisms.

Quality Control

The general purpose of quality control is to ensure that a maximum amount of the product being processed reaches the desired level of quality with minimum variation and that this is achieved as economically as possible. The products of natural raw materials are never exactly the same, so control is necessary to keep product quality within the standards set. Raw materials should be purchased from reliable suppliers who hold a current food manufacturer's registration.

Quality control generally involves inspections of three kinds:
* Raw materials
* Materials in process
* Finished product

If effective raw material and process controls are not put in place and only examination of the finished product is done, then quality conttol stops being a control and becomes merely an inspection. A good control system . rejects substandard ingredients before the process begins and once it has begun, prevents wastage of good raw material.

Food Borne Disease

Since the nutrients in the foods we ingest are the very same nutrients that microbes thrive on, it is logical that the microbes are among our greatest' competitors for the available organic food. For several reasons food borne diseases, or FBD, have· always plagued man, and for that matter every other living animal on the planet. In dirt and various forms of gore and muck, but our food, often taken from the pa!tly rotted carcasses of long-dead creatures, was covered with even worse. No matter, since our ancestors were hungry - probably near to starving a good portion of the time - the niceties of sanitation were rarely observed. Rather, our ancestors bolted down any food (maggots and all) that fell into their fouled hands regardless of its condition. If they were really lucky they didn't get sick, if they were mildly unlucky they got a few cramps and a brief, but messy case of the runs and recovered. However, if they really had bad fortune they became violently ill and frequently died writhing in agony in their own vomit and excrement.

Secondly, many pathogens have evolved to take advantage of the gusto with which humans ingest unsanitary meals to gain entry into our nutrient-rich bodies by hitching a ride in our food for their own nefarious ends. Recent studies indicate that consumers are very concerned about the contamination of their food with dangerous microbes. In one survey 77% indicated that the fear of 1/ germs" in their food was of greater concern than pesticide residues, product tampering, antibiotics in food or other safety risks. However, despite these concerns, studies show a significant lack of knowledge of consumers as to what constitutes safe food handling practices.

These studies show:

1. Most consumers erroneously believe that foodborne illness is caused by food prepared commercially rather than in the home. However, data show that 80 % of the food poisoning occurs in the home. While there are sporadic outbreaks of foodborne illness associated with commercial food products, studies indicate that foodborne illness are far more common in the home.

2. Many consumers are unaware that the most common foodborne illnesses in the US, caused by Salmonella and Campylobacter, may take several days to develop and often cause fevers.

3. Consumers often do not handle food safely at home as they are unaware of the importance of refrigeration, handwashing, and preventing crosscontamination between meats and uncooked foods in preventing foodborne illnesses in the home.

4. Consumers willingly change their habits when provided with the correct information.

5. Food poisoning kills 9,OOO Americans/year and sends 30 to 80 million to the doctor, emergency rooms or bathrooms with fever, diarrhea and cramps.

6. Bacteriological analysis indicates that it is better to eat food that has fallen in your toilet than food that has fallen into your kitchen sink.

Food Borne Diseases exist in two major categories; intoxications and infections. The former is the result of ingesting toxins produced by microbes that have grown on the food prior to it being eaten.

Botulism

Botulism is an intoxication that is caused by the ingestion of a virulent nerve toxin produced by the growth of the gram positive, obligate anaerobe, spore-former Clostridium botulinum. This bacterium appears to be a normal inhabitant of the soil, hence its ready contamination of most foods. It is able to grow in absence of oxygen in a wide variety of foods and in so doing produces a protein neural toxin, two to three grams (an amount equivalent to the quantity of salt in the average salt shaker on your table) of which would be sufficient to kill every human on earth.

However, the organism will not grow in the presence of oxygen or nitrate salts and it does not produce the toxin at a pH below 4.7. Only one strain, which is found associated with marine organisms, is able to produce the toxin at refrigerator temperature. The toxin is destroyed by boiling it at 100°C for 10 to 15 min. However, .the pore requires a temperature of 121°C for 15 min to kill it. The toxin acts by binding to nerve junctions and destroying the nerve. The symptoms, which occur usually within 12 to 36 hours, but which can take up to 8 days to appear, classically consist of double vision, dizziness, inability to speak, breathe or swallow. Death often occurs due to the inability to breath. The only treatment is the injection of antitoxin to the several varieties of the toxin. This treatment is only effective against free toxin, as once the toxin has bound to the nerves the damage is irreversible.

The entire canning process is built around insuring that all spores of this bacterium contaminating any canned food are destroyed in the sterilisation process. Industry has a sterling record in that deaths from commercial-botulism are very rare. This is influenced by the fact that once a product is known to contain botulism toxin none of that product is ever again purchased by a customer. The majority of botulism poisonings occur in Home-canned Foods prepared by grandma or your favourite aunt.

 Some interesting additional information about this disease is:
* Never feed raw honey to a child under the age of two because the botulism spores can grow in the immature gut and produce the toxin.
* The botulism toxin is being used to treat certain neurological conditions where nerves that shouldn't fire do. In these cases tiny quantities of the botulism toxin is injected into the nerve, which the toxin kills and cures the condition.
* Ducks and chickens often die from botulism poisoning by eating rotting material m which the bacterium has grown. However, vultures, which as you know, eat disgusting rotten, stinking carrion, are immune to the toxin through evolution.

Q Fever

This FBD is the result of infection by the gram negative, obligate intracellular bacterium Coxiella burnetii. This organism is associated with farm animals, with man usually considered to be an accidental victim; in fact it was first called the "wool cutters' disease" because Australian wool clippers frequently came down with it because of their close contact with sheep. It is stiit a common disease among those that work' with farm animals where it is spread in the dust and through direct contact with animal carriers. It produces a flu-like disease· that varies from being mild to very debilitating.

Although the majority of people who contact this disease recover, some strains of the bacterium are able to infect the heart, producing a fatal' disease. Because it is highly infectious, the onset rapid and the disease debilitating, it has been studied as a biological warfare weapon. The microbe produces forms which are sporelike in their resistance to heat and drying. Because of the frequency of milk contamination by C. burnetii is considered a FBD and because of the heat-resistant nature of this bacterium, the temperature of the pasteurisation process was increased a few years ago to 72°C for 15 seconds to eliminate it from milk.

Staphylococcus Aureus

Staphylococcus aureus is a common inhabitant of the human body, being found on our skin and in our nose and is considered part of our natural flora. This bacterium interacts with humans in many ways. It is a common cause of nosocomial infections that frequently causes death in the patients it infects, it is a prevalent cause of severe skin infections like boils and impetigo, it is the etiological agent of Toxic-SHock Syndrome and it is one of the major causes of FBD in the world because of its intimate association with humans. This bacterium has a number of characteristics that contribute to its many roles.

Although it is not a spore-former, it does tolerate high temperatures better than most non-spore-formers. It is able to grow in high salt and sugar environments which allows it to survive and flourish on the human skin and in rich, sweet foods. It produces a wide variety of toxins, depending on the strain and it tends to carry a large number of antibiotic resistant plasmids. It is, in short, a formidable adversary. It generally produces FBD in "rich foods", such as cakes, pies, potato salad and custards.

The usual scenario involves food that was prepared in advance and improperly stored for a long time before being eaten. During this storage period the contaminating S. aureus (from the nose and hands of the individual who prepared the food) grow rapidly, often in such perfusion that their yellow colonies can be observed upon close examination. During growth the bacteria produce a number of potent toxins, one of which, called a superantigen, mimics a protein involved in our immune response. This superantigen acts by over stimulating the T -cells to produce prodigious quantities of interleukin 2 which, in turn, induces fever, malaise, nausea, vomiting, diarrhea and shock, which are the classical symptoms of Staph food poisoning. This was discovered serendipitously by a physician who was treating cancer patients with interleukin 2 at different dosages and he noticed that at high doses they developed the classical food poisoning symptoms.

Staph food poisoning symptoms usually appear within 1 to 6 hours after ingestion and produces the symptoms described above. The disease is usually over within 24 hours and death is rare, usually limited to the very young or the old and infirmed.

Salmonella Gastroenteritis

Infections of humans by a variety of salmonella species is quite common in the US, being one of the most common causes of foodborne illnesses in the home. Salmonella are a genus of gram negative, small rod-shaped, nonspore-forming bacteria that are usually associated with animals, both wild and domestic. The problem occurs because many of the animal strains of salmonella, including ones that live in snakes, turtles and lizards, as well as chickens, horses, and turkeys, can infect humans and cause a severe gastroenteritis. This bacterium is released in the feces of the infected animal, thus when humans contract this disease it usually means that they have ingested fecal material due to unsanitary behaviour.

One of the most common sources of hun in salmonella infection occurs in the kitchen, both commercial and domestic. Unless the Highest Standards of sanitation are applied by knowledgeable individuals during the slaughter and preparation of food for human consumption, fecal material can contaminate the food. Such contamination can easily be spread- to other foods via kitchen utensils, cutting boards, by contaminated hands or contact with contaminated work surfaces. The salmonella are hardy microbes that are able to survive outside their hosts in water, on moist surfaces etc. for days to months, so cursory measures will not protect you from these dangerous pests. The. most common sources of salmonella infection are fecal-contaminated animal meats such as turkey, chicken, beef etc. and eggs. Victims ingest the bacteria which invades the intestinal mucosa setting up an infection that produces inflammation of the intestine resulting in diarrhea, fever, cramps, nausea, abdominal pain, and vomiting (Gastroenteritis).

The disease onset occurs within 8 to 48 hours up to several days and the disease lasts 2 to 5 days to as long as several weeks. Treatment involves fluid/ electrolyte replacement; antibiotics are only used to counter secondary infections. A serious, new form of Salmonella has appeared in the US in the past 10 years. This is a disease caused by Salmonella enteritidis. This bacterium has developed the ability to grow in the ovary or eggproducing organ, of chickens where it is deposited within the egg as it is being formed.

Other-egg-related salmonella are found on the exterior of the egg where they can be killed by washing with bleach or hot soapy water, however this new strain can only be killed by thoroughly cooking all parts of the egg. That is, the bacterium is not eliminated from soft-boiled eggs or "over easy" eggs. The disease produced by S. enteritidis has caused a number of deaths and is a threat to anyone who fails to cook their eggs properly. In our household we always cook anything with egg in it thoroughly. The disease can only be prevented by testing of egg-producing flocks and the elimination of all the infected chickens.

One common problem is the way in which eggs are stored prior to placement on the store shelves. In a recent investigation it was found that while the FDA rules specify that eggs should be stored at temperatures low enough to prevent the growth of S. enteritidis in them, many handlers do not adhere to these rules and examples of eggs being stored at room temperature in stores for several days were found. Perhaps you should inquire of your supermarket manager how their eggs are stored prior to being placed out for sale.

Clostridium Perfringens

Clostridium perfringens is a gram positive, obligate anaerobic, spore-former that is found in the gut of many animals, including humans. Besides producing a FBD, it is responsible for producing gas gangrene. As with fecal-oral route during slaughtering and food preparation. However, this disease is an Intoxication and not an infection. As with Staphylococcus food poisoning, this FBD is usually the result pf improper storage of food prepared in advance.

A holiday turkey is prepared, however during preparation the stuffing gets contaminated with C. perfringens spores (from poop) left on the turkey during their slaughter. The stuffing is subsequently packed tightly inside the turkey. Because stuffing is a excellent insulator, it may not get hot enough to kill the heatresistant spores. At the first serving of the turkey no disease occurs, however once the stuffing, containing the live spores reaches room temperature the spores germinate and begin to grow rapidly while producing toxins.

As the stuffing sits out for several hours before being stored in the refrigerator in a large bowl, bacterial growth continues and since the large mass of stuffing may take, several hours to cool down in the refrigerator, growth continues for several more hours. When the "leftovers" are eventually served they contain toxic quantities of bacterial products and the eaters become ill. The illness strikes within 8 to 16 hours and produces profuse diarrhea. Most victims recover in 1 to 4 days and no treatment is usually necessary except for the very young or the elderly.

Escherichia Coli 0157:H7

This is a new kid on the block in that the disease produced by this bacterial strain was first recognised in 1982 during an outbreak of a FBD in the State of Washington. E. coli is a normal inhabitant of the human and animal gut and is the most studied bacterium on the planet. It is a gram negative, motile, plump, non-sporeforming rod. The numbers 0157 and H7 refer respectively protein (H7). Although this strain had been first reported in 1975 it was not recognised as a FBD organism until the 1982 epidemic.

It is likely that there had been many previous outbreaks of food poisoning involving this bacterium, but the etiological agent had not been recognised and the FBD had been blamed on other organisms. This bacterium enter its victims via the fecal-oral route and produces and infection in the victim's intestine. 0157:H7 contains a plasmid that carries the gene for a virulent toxin. Once the infection is established, the toxin is released, causing Hemmorrhagic Colitis and Hemolytic Uremic Syndrome.

The former results in damage of the intestine accompanied by bleeding and in severe cases destruction of the intestine that can only be stopped by surgical removal of the infected tissue, oftep several feet of it. In the latter syndrome (HUS), the kidney is severely damaged and often completely destroyed. Death results from general organ failure due to a combination of the toxin effects and the failure of crucial organs.

The bacteria resides in food (and water) that is contaminated with fecal material, usually from cattle, although other sources may exist, including humans. The bacterium is easily killed by heat, but if products like hamburgers are not heated so that all parts of the patty reach a lethal temperature, the organism can survive to cause the disease. This bacterium has been cultured from raw milk, cheese, turkey roll sandwiches, chicken, pork, and raw vegetables; and recently in unpasteurised fruit juice. It has been spread between children at nursery schools due to unsanitary conditions.

The onset of the disease occurs 24 to 72 hours after ingestion. It varies from a mild gastroenteritis to the severe, often deadly course described above. Antibiotics seems to have little effect probably because once tissue damage sets in the blood supply is interrupted which prevents the drugs from reaching the infected sites. Surgical removal of the infected tissue is useful but very traumatic and it may not remove all the infection. It appears to be more severe in small children, possibly because they have not developed· general low level immunity to E. coli. The extent and seriousness of this disease was painfully illustrated by events that took place in Japan during the summer of 1996. Almost 6,000 people became ill with 0157:H7 and to this day the source of the infection is unknown.

Prevention of Food Born Diseases

The prevention of FBD is theoretically easy but practically difficult due to the nature of humankind. Basically the elimination of foodborne diseases requires rigorous application of basic rules of hygiene and sanitation that everyone learns in kindergarten but frequently fails to apply in everyday life.

Following are some of them:
* Wash your hands after pooping, especially if you're going to be handling food for yourself or anyone else.
* Wash your hands after playing with the dog, cat, ferret or alien, especially if you're going to be handling food for yourself or anyone else.
* Wash your hands after playing in the dirt, especially if you're going to be handling food for yourself or anyone else.
* Don't eat dirty or spoiled food.
* Don't eat off of dirty dishes or utensils .

Develop and practice good kitchen habits, including the following:

* Prepare all fresh meat dishes in a separate area of the kitchen.
* Do not use utensils used to cut up meat on other foods, like salad makings; use separate cutting boards for meat and vegetables; colour coded ones help without washing adequately in-between.
* Wash the meat preparation area (counter and stovetops) and utensils with bleach or hot soapy water when finished.
* Wash hands well between working with meat and vegetables by scrubbing with soap for 30 seconds.
* Cook all foods, especially meats, thoroughly until there is no sign of redness in the center.
* Always assume that fresh food is contaminated, no matter how clean it looks or how well it is packaged and wash it thoroughly in hot, soapy water, removing all dirt, feces etc.
* Never store food made with raw eggs (e.g. hollandaise sauce) at room temperature.
* Store all food that is prepared ahead of time in small batches in the refrigerator.
* Put away leftovers immediately after the meal in small portions that will cool quickly in the refrigerator.
* Avoid unpasterurised niilk and milk products and juices.
* In your shopping cart keep meats bagged and separate from ready-to-eat foods; asked that meats be bagged separately at the checkout stand.
* Store meats separately from all other foods in the refrigerator.
* When eating out don't order ground meat products and avoid salads.
* Don't drink unchlorinated or any water not treated to remove bacterial viruses.

Common Food Poisoning Illnesses

Clostridium Perfringens

* Foods involved - Contaminated poultry meat and meat products, especially stews, gravies and pies.
* Main symptoms - Abdominal pain, diarrhoea and nausea.
* Onset of illness - 8 to 22 hours, (usually 10 to 12 hours).
* Source - This organism is found in the waste of animals and man, and often in raw meat and in soil. It thrives in airless conditions and survives ordinary cooking.

Salmonella

* Foods involved - Contaminated meat and meat products, especially poultry. Custard, cream, milk and egg products, and salads.
* Main symptoms - Fever, headache, aching limbs, abdominal pain, nausea, diarrhoea, and sometimes vomiting.
* Onset of illness - 6 to 72 hours (usually 12 to 36 hours).
* Source - Salmonella bacteria are often present in the waste of man and animals, (especially rodents and poultry). This illness is infectious and can be spread to other people.

Staphylococcus

* Foods involved - Contaminated moist protein foods. Meat, eggs and fish products.
* Main symptoms - Abdominal pain, severe, vomiting, diarrhoea, abdominal cramps, and sometimes collapse.
* Onset of illness - 1 to 6 hours (usually 2 to 4 hours).
* Source - Staphylococcal bacteria may come from infected sores, nasal secretions and skin (perspiration and hair). The toxin that causes illness can survive ordinary cooking.

Campylobacter

* Foods involved - Contaminated meat and meat products, especially poultry. Contaminated water, and raw milk.
* Main symptoms - Diarrhoea, abdominal pain, fever, nausea, and vomiting.
* Onset of illness - 1 to 10 days (usually 3 to 5 days).
* Source - Campylobacter bacteria are often present in the waste of man and animals (especially domestic animals and poultry). This illness is infectious and can be spread to other people.

Chemical Poisoniong

* Foods involved - All foods can be affected; (eg. soap powders/rat poison getting into dry food mixes; garden poison residues in soft drink bottles).
* Main symptoms - Abdominal' pain, nausea, at times vomiting and diarrhoea. These symptoms may not be present for a lot of poisons- in these cases often the first symptom is of collapse.
* Onset of illness - Usually less than half an hour.

Other food-borne diseases of note are Listeria, Yersinia and Cryptosporidium.

Listeria

* Foods involved - Contaminated processed meats and meat products, raw milk, seafood, poultry and vegetables etc (eg coleslaw).
* Main symptoms:
a. Normal host : Acute/mild fever, influenza-like symptoms.
b. At risk host: Fever, intense headache, nausea, meningeal irritation and vomiting. Infection of the foetus, septicemia, meningitis, and still-birth.
* Onset of illness - 3 days to 3 weeks.
* Source - Listeria bacteria are commonly found in soil, water, vegetation, domestic animals, and man.

The illness, though infectious, is relatively rare. Pregnant women, the elderly, and those with lowered immune systems.

Yersinia

* Foods involved - Contaminated meat and meat products, especially pork mince and tongue. Contaminated water, seafood and raw milk.
* Main symptoms - Under 5 yrs diarrhoea, (sometimes bloody). Over 5yrs abdominal pain (like appendicitis), also fever, joint pain sore throat and rash.
* Onset of illness -12 hrs to 11 days (usually 24 to 48 hours).
* Source - Yersinia bacteria are often present in the waste of farm animals (especially pigs) and infected pets-(puppies and kittens) and man.

This illness is infectious and can be spread to other people.

Cryptosporidium

* Foods involved - Contaminated food and water, unpasteurised milk or fruit juices.
* Main symptoms - Diarrhoea (often watery), abdominal cramps/pain, and anorexia. Fever, nausea, and vomiting occur less often.
* Onset of illness - 1 to 12 days (usually 7 days).
* Source - Cryptosporidium parasites are often present in the waste of farm animals, poultry, pets and man.

This illness is infectious and can be spread to other people.

In "Food Hygiene", Dr. Kavita Marwaha, editor, Gene-Tech Books, New Delhi, 2007, excerpts p. 147-175. Digitized, adapted and illustrated to be posted by Leopoldo Costa.