WAYS OF GETTING FOOD POISONING

1.   MICROBIOLOGICAL CONTAMINANTS AND PARASITES:

Under these contaminants we have the following organisms:

i (a)       Bacteria:    These are .minute and single-celled organisms of different shapes and activities. There are thousands of different types and many perform useful functions such as decomposition of wastes, making of vaccines, etc. Therefore, not ail bacteria are dangerous to health. They could not be seen individually except in thousands or in a clustered form or with the aid of a microscope.

The types that may be spread by food are round and rod-shaped. Some are mobile in fluid and move about by means of hair-like structures. Some could resist heat and become difficult to destroy because oj~ their hard cover capsule while others can produce spores when the condition is unfavourable for growth.

Most food-poisoning bacteria cause symptoms only when eaten in large numbers after multiplication in food. The appearance (taste or smell) does not change. It is only the bacteria that break down the protein in food  so  that   there  is  a  physical  spoilage  leading  to  putrefaction detectable smell that does not usually cause food poisoning.

Bacteria multiply by simple binary fission (division info two) and this takes place under suitable condition (i.e. between 20-30 minutes).

Most of them require air to live actively but some can multiply only in the absence of oxygen.

Harmful microorganisms grow best at the temperature of the body, which is 37T (98.6°F) although, the majority will multiply between I5"C and 45°C. As the temperature increases from 37°C (98.6°F) to 63°C (I45°F) the rate of growth slows down and at a temperature above this bacteria will gradually be killed. The length of time and the temperature required to kill them depend on the type of bacteria and the food involved. They are normally killed in 1-2 minutes in boiling water unless they are able to form spores.

If the temperature of the' food is decreased from 37°C (98.6°F) to 1()°C (50°F) the bacteria will continue to multiply but the rate of multiplication will slow down as the temperature decreases. Bacteria are not killed by low temperature but they are dormant, "his means that they stay alive but stop growing and multiplying. Food poisoning bacteria will not grow at the temperature of the domestic refrigerator, 1-4°C (34-39llF), but some spoilage bacteria are able to grow and multiply slowly. When the foods arc removed from the refrigerator and warmed up, the rale of bacterial growth increases. Pathogenic and spoilage bacteria remain dormant even in frozen food, but as soon as the food is thawed they will start to grow and multiply again.

 (b)      Viruses:

These are very minute micro-organisms causing an outbreak of intestinal illness of a particular pattern, but the investigation of faeces from such incidents has techniques, particles of faeces. So far given inconclusive results, but with improved of gastro-enteritis have been isolated from the People who eat raw shellfish or live in coastal' polluted waters can contract infection in this way Viruses cannot multiply in foods, only in living tissues,; thus if they are agents of food poisoning their spread from hand of human carriers and water to food stuff is important,

They are destroyed by the temperatures reached in normal cooking methods and so viral food poisoning is usually transmitted by food which has not been cooked or has been handled after cooking by a human who is a carrier of the virus. Inadequately cooked shell fish collected from sewage - contaminated waters have caused viral food poisoning.

(c)        Fungi:

These are flow forms of vegetable lives including many microscopic organisms capable of producing superficial and systemic diseases in man. Some fungi produce substances which are poisonous to man and animals e.g. aspergillus flavours growing in groundnuts, peanuts, and other cereals and produces aflatoxin which ca-usc.s hepatitis when consumed.                  l

(d)       Parasites:

Many animal parasites have developed life cycles involving their residence in animals or plants serving as foods for man e.g. tapeworms, flukes and other nematodes. Hazards to human beings from animal parasites especially in the tropics are related much more to the poor standard of personal hygiene.

2.         Naturally Occurring Toxic Contaminants

II has been discovered that some plains and animals may be naturally poisonous to man.

Some of the important and common ones are as

follows:

(a)        Solanine   - found in potatoes

(b)       Cyanide   - found in cassava

(c)       Alkaloid   - in mushroom

(d)          Heavy metals   - in mussels (snail-like seafood) Aflatoxin - in groundnuts

(e)          Aflatoxin   - in groundnut

(f)           Ergot –  found in rye

(g)          Gossypol  -  found in cottonseeds etc

Unintentional Contaminants and Residues

It has been recognised that various chemicals, harmful or otherwise, may be incorporated unintentionally during the production, processing, storage, distribution and consumption of food. Pesticides necessary for the control of insect and fungal pests in agriculture and ectoparasites in animal husbandry may be harmful when improperly used as may some food additives. Excess amounts of certain growth - stimulating drugs and hormones may be found as residues in edible animal tissues and plants. Environmental contaminants also prove health hazards. 'The following are forms of such contaminants:

(a)         Industrial and Household Effluent and Wastes:

The least of industrial and household effluent is formidable. Many of these food chemicals do not enter the food chain and nutrient cycles but may be hazardous to man through environmental pollution. Accidental discharges into rivers or underground waters from industrial sources or illicit disposal of toxic wastes are constant causes of food poisoning. Heavy metals like mercury and lead when settled in the water are led by bacterial actions to more toxic organic form that causes minimal and plumbism respectively,

(b)        Pesticides and Residues:

The use of pesticides in the control of insects and other pests in the production and processing of food cannot be overemphasized. However, some if not properly used could be hazardous to the man, animals and plants.

e)       Adverse Effects of Industrial Food Processing; Processed foods canned in certain types of containers may react with the containers to produce poisons which can cause illness. Preservation of food for the purpose of long distant transport and storage facilities has

been threatening the health of the consumers.

Adulteration of food can in certain circumstances be harmful to health as well as defrauding the consumers as regards the identity or quality of

(d)      Vermin, Domestic Animals and Birds:

Domestic animals should not be allowed to roam in any part of the premises where meat and other foods are kept* handled or prepared. Food premises should also be guarded against infestation of rais, mice and other vermin; remedial action should be taken when necessary. Contamination of food, equipment and utensils with poisoned baits must be avoided. Birds and bats should not near the premises where foods are kept, prepared and or sold.

4.        Deliberate or Intentional Additives

Food additives are chemicals purposely or intentionally added to foods 10 better the products in some way or enhance their use. The main reasons for using food additives are:

.

(a)        To improve the nutritional value of food.

(b)        To enhance flavour

(c)        To maintain appearance, palatability and wholesomeness.

(d)       To control pH level

(e)       To add colour                            ,

(f)       To impart and maintain desired consistency.

In food establishment, additives may be used as:

1)            Preservatives: These are chemicals used for the preservation of certain foods. Such as:

(a)          Sulphur dioxide in the making of sausages, grape juice, mineral    waters, beer, jams, etc.

(b)          Benzoic acid in the making of soft drinks, fruit juice, etc.

(c)           The propionic acid in the making of bread, etc.

(d)          Others like citric acid, vinegar, sodium nitrite, meta-bisulphate, etc.

1.            Flavouring Agents:

These additives add flavour to fo0ds such as Al, magi, Ajinomoto, etc.

for the preparation of soup and stew.

2.            Colouring Agents:

These add colour to food e.g. arsenic, cadmium picric acid, etc. Some

are used in the making of ice cream, pop-corn, soft drinks, bread, etc.

3.         Sweetening Agents:

These add taste to food such as sugar, saccharin, cyclamate, etc. They are used in the making of jam, jelly, cakes, etc.

The illegal use of these additives can mask and disguise the use of faulty processing and handling techniques; deceive the consumers an4 reduce the nutritional value of the food. The use of additives is justified if they can maintain the nutritional quality of food; reduce food wastage and make food attractive to the consumers in a manner, which does not lead to deception. There is no harm when these chemicals are properly used and established standards are not exceeded.

Bacterial Organisms that Cause Food Poisoning and Food Infection

There are a lot of bacterial organisms that cause food poisoning and food infection. The common ones are hereunder discussed:

1.       Salmonella:

Among the organisms of animal or avian origins causing infection in man are salmonella group of organisms. There are about 1,800 known serotypes of these organisms, but only 50 of them occur commonly. The organism is capable of causing diseases in man and animals when taken into the body in sufficient number. All the types included in the genus salmonella are related to food poisoning. Some appear to be restricted to a single host species and are not found in other animals, e.g. Salmonella abortus ^ovis Causing abortion in ewes and salmonella gallina rum, the cause of fowl typhoid.

Conversely, some salmonella type e.g. S. Typhi,  S. paratyphoid A, B and C cause a predominantly febrile illness known as enteric fever. The paratyphoid syndrome tends to be milder than that of typhoid. In the latter, the period of incubation is longer/ a higher temperature is produced, the organisms may be isolated from the blood and sometimes. Urine and the mortality rate are high.

Salmonella may be divided into the following three groups based on host predilections:                                                           

1,            Those primarily 'adapted to man e.g. Typhoid and paratyphoid,

2.         Those primarily adapted to particular animals e.g. Salmonella enteritidis, salmonella Gallinari um, salmonella Dublin, etc.

3.            Those unadapted. These are among the number that attacks man and animals   and do   not show, any host preference e.g. Salmonellosis (Jay James 1978 and Betty and Hobbs et al 1978).

Others,- too responsible for .the cause of food poisoning or gastro enteritis are S, Typhimurium and S. enteritidis. These organisms are viable organisms in man that cause food poisoning by infection i.e, by the invasion of the body. They reach food directly from animal excreta at the time of slaughter; from human excreta or water polluted by sewage; also in the kitchen, they may be transferred from raw food to cooked ones by hands, utensils and other equipment. The illness usually occurs when the organisms are ingested in large numbers, but this is done if contaminated at a suitable temperature that will enhance their growth or multiplication.

Incubation Period-

The incubation period of the infection is within 6-36 hours of eating the contaminated food: although, it may be longer. In many human infections, the affected individuals continue to excrete the organisms for few days or months (that is act as carriers). In the case of S Typhi, the carrier stale can persist for life because they continue to harbour the bacilli in their gal! bladder or kidneys and many excrete them intermittently for many years.

Signs and Symptoms:

The signs and symptoms of salmonella food infection are fever, headache, abdominal pains, diarrhoea, vomiting.

Sources:

The stool of animals suffering from the infection, meat and meat products, egg and egg products, poultry, raw milk, etc.

2,        Staphylococcus Aurous:

Staphylococci are small rounded bacteria which gather together in clusters. The strain that is responsible for causing: Food poisoning is staphylococcus aurous that produces poisoning substance in food before it is eaten.             

In man, the main reservoir of staph aurous is the nose. From this source, these organisms find their way to the skin and into suppurating wounds and septic infections such as boils, carbuncles, pimples styes, etc either directly or indirectly. The most common skin source is the arms, hands, and face.  In addition to skin and nasal cavities, staph aurous may be found in the eyes, throat and in the intestinal tract. From these sources, they find their way into air and dust, onto clothing, and in other places from which they may contaminate foods. This organism does not cause food poisoning by itself but it is capable of producing exo-toxin responsible for the illness.

In contrast to the "infection type" of food; poisoning caused by salmonella, this is a "toxin type", i.e., it is due to the ingestion of preformed toxin, not to any action of the organisms themselves upon the patient,

The organisms are readily destroyed by heat, but the toxin is more resistant. This organism causes food poisoning by intoxication and this has a shorter incubation period because of ihc already produced toxin in food.

Incubation Period:

Incubation period is within 1-6 hours of eating the food.

Signs and Symptoms:

The signs and symptoms of staphylococcus food poisoning arc diarrhoea, abdominal pain, cramps sometimes followed by collapse, nausea, severe vomiting, etc.

Sources:

Staphylococcus aurous is frequently present in the human nose and throat and on the skin of healthy people. It is known as a commensal because it is completely harmless when present in these areas. H is also found in boils, styes, pimples and septic cuts. The food sources arc unpasteurized milk, poultry, custard, etc.

3.         Clostridium Perfringens (Welch):

This species is commonly present in the soil and in the intestines of animals and man. Il can also be found in raw meat, poultry and other foods including .dehydrated products. The organisms produce hard structures called spores which survive for a long time under unfavourable conditions by means of these spores which remain dormant in food, soil and dust. They are anaerobes. Illness occurs after eating food; grossly contaminated by the organisms, which have multiplied from spores that survive cooking.

Clostridium perfringens does not produce toxin when it is multiplying in food stored at a warm temperature, but when that food is oaten the bacteria form spores and at the same time a toxin, which irritates the intestinal wall causing diarrhoea. This is not exactly the same as toxic food poisoning or infective food poisoning but has some characteristics of both. The incubation period is longer than with toxic food poisoning as caused by staphylococcus aurous and shorter than infective food poisoning as caused by salmonella.

Food poisoning due to this organism usually occurs in institutions or sources associated with public functions such as Birthday parties, wedding or marriage and funeral ceremonies. This organism produces toxin in the intestines (enterotoxin). The intoxication due to this organism is caused by food, which has not been properly processed or cooked to destroy the spores.

Incubation Period:

The incubation    period    is   within   8-22   hours   after   consuming   the contaminated food.

Signs and Symptoms:          

The.se arc abdominal pain, diarrhoea, nausea, vomiting may be rare.

Sources; The sources arc mea4, poultry, beans, etc.

4. Clostridium Botulinum:

This is the organism that causes botulism. It has some similar characteristics to clostridium perfringens. It I forms spores under an unfavourable condition. It is also an anaerobic spore-bearing bacillus.

Food poisoning by Cl. Botulinum is very rare but at the same time, it is greatly feared because the majority of cases are fatal. The toxin produced by the organism is the most poisonous of all. It has been reported that 1 gramme of the toxin produced is possible to destroy the entire world population.

Botulism has characteristics different from other forms of food poisoning. Its signs and symptoms mainly affect the central nervous system instead of the gastro-intestinal tract. The little effect on the intestine is the reverse of what it is in others. This is constipation and mild fever.

The spores are resistant to heat and survive burning and high temperature.

Incubation Period:

The incubation period is within 24 hours to > days after food intake.

Signs and Symptoms:

The signs and symptoms are a headache, weakness, constipation, paralysis of the throat, double vision (diplopia), drooping of the eye-lid (ptosis), shaking or rolling of the eyeballs side-ways (nystagmus), etc. As the mischief drops, prolapsed of the tongue and inability to swallow may follow; consciousness persists until death.

Note:    Ptomaines:

Are chemical substances formed by the action of putrefactive bacteria on decomposed food and appear late in the process of decomposition so that meat or food containing ptomaine is nasty and offensive and would not be eaten by any sane person. The danger of ptomaine food

poisoning is therefore very remote.

5.        Bacillus Cereus:

These are common aerobic sporing organisms normally present in the soil, dust and water. The spores also survive cooking and will subsequently germinate into bacilli under favourable condition grow and produce entero-toxin.

Incubation Period:

The incubation period is within 1-5 hours of consumption of food.

Signs and Symptoms:

The signs and symptoms are diarrhoea, abdominal   pain,   nausea, vomiting are rare, etc.

Source: Sources arc beans, cereals, etc.

6:        Vibrio Parahaemolyticus:

This is a marine organism, which was first insolated during an outbreak of food poisoning in Japan in 1951. The organism grows in sewage polluted coastal waters and a large number of the organizes multiply in seafood such us fish, oysters, clam, crabs, shrimps, etc.

The organism causes food infection and the symptoms have been likened to those of both cholera and dysentery.

Incubation Period: The incubation period is within 10-20 hours after eating raw or inadequately cooked sea-foods.

Signs and Symptoms:

The signs and symptoms are profuse diarrhea, dehydration, vomiting, fever, pyrexia, chills, etc.

Sources: The sources are fish, shellfish, etc.

7.         Escherichia Coli:

This is present in the intestinal tract of healthy people and is not always harmless. A few serotypes are enteropathogenic, entero-invasive and entero-toxigenic in young children (usually under two years old) and older adults above 60 years who contract the infection as a traveller's diarrhoea when travelling abroad.

Incubation period:

The incubation period is from 12-24 hours after eating contaminated food.

Signs and Symptoms:

Signs   and   symptoms   are   abdominal   pain,   fever,   diarrhoea   and sometimes vomiting.

8         Vibrio Cholera:

This organism is exclusively an organism of man, multiplying in human intestines. It produces an entero-toxin. This acts on the intestinal epithelium and provokes sustained out-pouring of water and electrolytes, manifested clinically as a profuse watery diarrhoea, vomiting, and rapid dehydration, collapse etc, -

Incubation Period:

The incubation period is from 1-5 days (usually 2 days).

Sources: Sources arc fish, shellfish, vegetables, water mainly, etc.

9.          Brucella:

This is bacillus responsible for causing undulant fever in man.  Brucella abortus, brucella eliteness and brucella suits are primarily pathogens of cattle, goats and pigs respectively. This organism may be excreted in unpasteurized milk and gives rise to undulant fever or brucellosis in hose who consume contaminated raw milk and milk-products.

10.       Streptococcus:

The group of streptococci generally associated with food poisoning consists of faecal streptococci, especially streptococcus faecal is. Others are streptococcus viridian and streptococcus phones, but this may be treated in the same way as the transmission of typhoid lever or scarlet fever by foods.

Streptococcal food poisoning is caused by streptococcus faecal is strains.

Incubation Period:

The incubation period ranges from 2-22 hours after ingestion of food. The signs and symptoms are the same as food poisoning caused by clostridium perfringens and Bacillus cereus.

11.      Shigella:

This organism causes bacilliary dysentery, e.g. Shigella clysonteriae, shigella flex inert, shigella boy clip and shigella sonnei.

Incubation Period:

The incubation period is from 1-7 days, usually 1-3 days.

Signs and Symptoms:

Diarrhoea, lever, nausea, vomiting, cramps, etc.

Sources:

Man is a reservoir, but the main sources are contaminated food and water.

Conditions That Favour The Growth Of Bacteria In Food

The following conditions favour the growth of bacteria in food;

1.          Food: Like all living things, bacteria need food.  They will live and multiply in many foodstuffs, particularly those which are high in protein and support their growth, e.g. meat, poultry, meat-products, milk and milk-products, eggs and e^g-products, etc. These foods are called high-risk foods.

:

2.          Temperature:  There  must be a suitable temperature to be maintained  to permit the growth of bacteria.     This is the temperature of the body, which is 37°C (98.6°F). There are three groups of bacteria that are distinguished according to their

temperature requirements:

-

(a)        Psychrophilic  Bacteria     -  These  bacteria  grow  at temperature below 20UC that is about 10°C.  It is known that   some   are able to cause food spoilage at the temperature of a domestic refrigerator (i.e. 4°C).

(b)        Mesophilic Bacteria:   These bacteria thrive best at an optimum temperature range of 37°C (98.6°F), which is the body and kitchen temperature.    They cause food poisoning and are responsible for most food spoilage conditions.

(c)        Thermophilic Bacteria:   These bacteria thrive best at quite a hot temperature i.e. up to 60°C (140°F). This gr6ii# of bacteria is troublesome in food canning.   

3. Water (Moisture): Bacteria cannot multiply on dry foods rather they remain dormant. Since water is essential to life, bacteria require water for survival. Most foods contain sufficient water for bacterial growth but dehydrated products