By Rosman Ahmad
The Sun, February 13, 1996
Food poisonings are syndromes acquired as a result of ingesting contaminated foods, that is foods that contain infectious, toxigenic micro-organisms or noxious elements.
Although the problems of food safety has existed for as long as man has, only limited success in the diagnosis and prevention food poisoning has been achieved. This is because most victims recover rapidly and usually believe they have consumed something that does not agree with the stomach and as such feel there's no need to consult a doctor. Recorded food poisoning incidences can be traced back to as early as the 9th century. Around 886-911 AD, Emperor Leo IV of Byzantium made a decree that forbade the eating of blood sausage due to its harmfulness to health.
In Malaysia too, food poisoning incidences are certainly not rare. Malaysia's hot and humid climate easily enhances the multiplication of micro-organisms. These micro-organisms can cause cholera, typhoid and other contagious diseases that can be spread by eating food prepared by an infected person.
Micro-organisms such as Salmonella, Staphylococcus aureus, Clostridium botulinum, Shigella, Escherichia coli, Vibrio cholera, and Listeria monocytogenes are very common causes of food poisonings. The table summarises the different types of micro-organisms, symptoms and characteristics of illnesses involving food poisoning.
| Illness | Bacteria | Symptoms | Characteristics of Illness |
|---|
| Staphylococcal poisoning |
Staphylococcus aureus. Bacteria that grow in food and produce a toxin that is extremely resistant to heat. Bacteria grow profusely with production of toxin at temperatures between 6.5 degree and 46 degree Celsius. Grow in pre-cooked hams, milk, custard, cream fillings, salads, mayonnaise and other cream base foods. |
Symptoms are nausea, vomiting, retching, abdominal cramps, diarrhoea, chills, headache, fever dizziness and muscular weakness. |
Transmitted by food handlers who carry the bacteria and by eating food containing the toxin.
Onset: usually within 3 - 8 hours and may last for 1 to 2 days. |
| Shigellosis or Bacillary dysentery |
Shigella bacterium. Grow rapidly at or above room temperature. Usually found in water, fruits, eggs, shrimp, vegetables, oyster, flour, milk and other diary products. |
Common symptoms are nausea, vomiting, diarrhoea, stomach cramps, weakness, vision problems, headache, difficulty in swallowing, slurred speech, dilated pupils and progressive paralysis. |
These bacteria will attack the mucosal surface, penetrate epithelial cells and multiply within the mucosa to cause the disease.
Symptoms appear eight hours to eight days after ingestion. The course is usually between 3 to 6 days, however it can be fatal.
|
| Salmonellosis |
Salmonella bacteria. Most often found in poultry, eggs, ham, lettuce and candy bars. About 1200 species and one cause typhoid fever. Grow and multiply at temperatures between 6.5 degree Celsius and 46 degree Celsius. |
Include fever, chills, dizziness, headaches, nausea, vomiting and abdominal pain. |
Transmitted by eating contaminated food, or by contact with infected persons or carriers of the infection. Also transmitted by insects, rodents and pets.
Onset usually within 12 to 36 hours and may last between 2 to 7 days.
|
| Cholera |
Vibrio cholera. Usually found in uncooked fish and shellfish harvested from contaminated water. |
Range from mild diarrhea to severe dehydration. |
Occur within one to three days after ingestion.
Hospitalization is required for severe cases.
|
| Traveler's diarrhea |
Escherichia coli. Spread by unhygienic water and poorly prepared food. |
Toxins that will cause severe diarrhoea. |
Course last for several days. |
| Botulism |
Clostridium botulinum. Spore-forming organisms that grow and produce toxin in the absence of oxygen, such as the inside sealed container. The bacteria can produce a toxin in low-acid foods that have been held in the refrigerator for 2 weeks or longer. Spores are extremely heat resistant. Spores are harmless, but the toxin is deadly, reported to be 7 million times more lethal than cobra venom. |
Inability to swallow, speech difficulty, abnormality of sensation, difficulty in breathing, double vision, dry mouth and blurred vision. |
Transmitted by eating food containing the toxin.
Onset usually within 12 to 36 hours or longer.
Duration: 3 to 6 days.
Antitoxins are available. |
Outbreaks of food poisoning are commonly caused by the poisonous substances produced by the staphylococcus strains of bacteria. The contamination and subsequent growth of micro-organisms in foods can occur at several stages between harvest and consumption.
Contamination may occur as the result of human interaction during slaughter, harvest or primary handling and processing.
Packaging provides an additional opportunity for contamination. The contaminants that have got into the food at this point are able to proliferate during storage unless storage conditions are ideal. Quantity food production for group feeding and storage in vending machines add further dimensions to the problem. When food enters the home, there are other opportunities for contamination and growth of micro-organisms.
In other words, at every point along the chain, possibility of various types of contamination exist and keen perception of the potential hazard should be maintained. Every precaution should be taken to guarantee an absolute minimum risk to the prospective consumer. Therefore, food handlers should be careful so that the consumer can be spared the risk of food poisoning.
Even when food is safe from insidious levels of micro-organisms when it is brought into the home, potential poisoning still exists. Maintaining the standards of hygiene in all aspects of food preparation at home is very crucial.
Personal hygiene, good kitchen sanitation practices and appropriate storage of food should be strictly maintained.
Food contamination that causes discomfort to the victim is the most common type of poisoning. In addition, food poisoning may also be caused by chemical poisons used in the cultivation of plants as well as chemicals from containers storing the food.
In 1995, 28 reported food poisoning cases involving 907 victims with two deaths were reported nationally. Of this, 681 were schoolchildren. Thus far this year, there have been two cases reported - one in Sabah that claimed 438 victims and the other in Pahang with 184 victims, both involving schoolchildren. This is an alarming figure.
Since most food poisoning cases have taken place at school canteens, certain measures should be drawn to ensure that all canteen operator serve food which is safe for consumption.
Rules and regulations regarding food safety should be reviewed to protect our children from being poisoned by unprincipled individuals. Continuous inspection should be made by the city council or health department to all schools. Not only should maximum fines be charged to those who do not comply, new laws should be initiated to prosecute them for criminal offence.
Listed below are some safety measures to ensure safe food-handling.
- It is the responsibility of canteen operators to make sure that all their staff are free from any diseases that can be transmitted through food during preparation. Infected people should not be allowed to prepare or serve food.
- Always wash hands thoroughly with soap and water before beginning work with food and at any time the hands are soiled during preparation. Personal habits such as running the hands over a lock of hair to brush it off the face and licking fingers need to be rectified because these can be prime sources of contamination. Clothing and nails must be clean and the hair always covered. Use rubber gloves if the hands have cuts or sores.
- Always use clean utensils for tasting foods to evaluate the seasoning mixture. Use the tasting spoon only once and then have it washed before using it again.
- Make sure that the kitchen or cooking area is always clean. All dishes should be washed thoroughly using soap or detergent and rinsed thoroughly with very hot water. Use a cutting board made of plastic instead of wood since it can be cleaned easily.
- Prepared or unprepared foods should be stored at proper place and temperature. The refrigerator's temperature should be kept at lower than 4 degree Celsius so that the food will be below the optimum range for the growth of micro-organisms.
- Temperatures between 4 degree Celsius and 60 degree Celsius are ideal for such growths. Meats, milk, eggs, creamed foods, egg-containing products, fish, gravies, poultry and salad with mayonnaise dressing should not be stored within these temperatures.
- Thaw foods in the refrigerator or cook them frozen. If you have to thaw them, use a microwave oven. Once thawed, foods should not be frozen again.
- Avoid storing food at room temperature as much as possible because gradual cooling encourages the growth of Salmonella.
- Always keep cold foods cold, hot foods hot or eat it at once. Store leftovers promptly after each meal. Refrigerate food quickly. Do not allow it to stand at room temperature. When in doubt, throw it out. Dispose of foods with strange odours and those that do not appear normal in colour.
- Inspect all food containers before opening and serving. Do not serve or consume food from damaged, bulging or leaking cans. Never use eggs that are cracked. Do not use expired products.
The writer is a Science Officer at the National Poison Centre, Universiti Sains Malaysia, Penang.
