Be aware of food safety in order to avoid food poisoning. Jonathan Liautrakul reports
It is not just a simple case of suffering a stomachache when food poisoning lands one in hospital. If the food poisoning is severe, patients may end up being dehydrated as they will not be able to keep down even a sip of water. This was experienced by many of the 235 children and 12 teachers felled by contaminated food in three preschools earlier this month. The preschools – Pat’s Schoolhouse, The Children’s Place and Learning Vision – all used the same caterer, whose services they have terminated. Investigations are still ongoing. To date, 34 people have been hospitalized and at least 14 have since been discharged.
An illness caused by food contaminated by bacteria, viruses or toxins can spread like wildfire, said Adjunct Assistant Professor Charles Vu, a senior consultant with the department of gastroenterology and hepatology at Tan Tock Seng Hospital. Food poisoning can be divided into two categories. The first involves infectious agents such as viruses, parasites and bacteria like E. coli, campylobacter, shigella and clostridium.
Common bacteria-induced food poisoning includes salmonella, which is found in undercooked poultry, eggs and meat; and vibrio parahaemolyticus, which is found in raw seafood. Viruses are also common in food poisoning. The norovirus and rotavirus, in particular, affect children and may cause damage to the walls of the intestines. These viruses are usually passed on when contaminated food is ingested.
The other category includes toxic agents, such as poisonous fruits or mushrooms; improperly prepared exotic food, such as fugu sashimi; and fruit and vegetables that have been exposed to pesticides.
The most common symptoms of food poisoning are diarrhoea caused by intestinal damage by bacteria, vomiting, loss of appetite, abdominal pains and fever. The inflammation of the gastrointestinal tract by such bacteria leads to the temporary disruption of its ability to absorb and stimulate secretion of fluids. The body tries to get rid of the “poisons”, resulting in vomiting and diarrhoea. The disruption of the immune system results in fever.
Symptoms may last for more than a week and could affect an individual or a group of people who ate the same food, causing an outbreak. Symptoms vary depending on the organism. “Fever suggests an infection with an invasive bacteria like salmonella or shigella, while symptoms that begin within a few hours of ingestion suggest the presence of a preformed toxin,” said Dr Limin Wijaya, a consultant with the department of infectious diseases at the Singapore General Hospital. A preformed toxin is produced by bacteria present in food when the bacteria multiply.
A stool culture test is the usual method to locate the culprit. Also important is the patient’s clinical history and symptoms. Certain types of food may give a clue to the types of bacteria present. For instance, E. coli may be found in beef and raw salads while campylobacter is traced back to milk and chicken. Most victims of food poisoning recover spontaneously, though antibiotics may be prescribed for serious cases of bacterial poisoning. Only a very small minority, especially those with pre-existing major illnesses, may develop consequences such as arthritis, and liver and kidney failure, if the condition is left untreated.
Dehydration is the main danger in food poisoning because of the fluids lost through vomiting and diarrhoea. One should not eat food while nauseous but, instead should drink plenty of fluids, taking small frequent sips of clear liquids like barley water or porridge, said Dr Lee Wee Yee, a senior consultant at the department of accident and emergency at Changi General Hospital. Rest is also important. If the patient is unable to drink, then he may need to be admitted to a hospital to be given fluids intravenously. “A presence of fever or blood in the stools may indicate a more severe form and one should then see a health-care practitioner,” said Dr Wijaya. The length of hospitalization due to food poisoning ranges from a day to a week, depending on the severity of the condition.
Eating should begin slowly once the patient is able to tolerate fluids. Dr Lee said: “Initially, one should consider eating rice, wheat, bread, potatoes, low-sugar cereals, lean meat and chicken. Milk can be given safely, though many may experience additional stomach upsets due to lactose intolerance.” The way to prevent food poisoning is to take safety precautions during the handling, cooking and storage of food.
Practise “safe shopping”
Purchase frozen food items last and bring them home to store as soon as possible. Avoid picking food in torn packages and buying food which is past its expiry date. In addition, keep raw meat and poultry in separate shopping bags, away from other foods. Dr Limin Wijaya, a consultant with the department of infectious diseases at the Singapore General Hospital, said: “This is especially so for ready-to-eat food such as salads, which can have cross contamination with raw meat.”
Store food safely
Place raw meat, poultry or fish in the coldest section of the refrigerator. Dr Lee Wee Yee, a senior consultant at the department of accident and emergency at Changi General Hospital, advised: “To slow bacterial growth, the temperature in a refrigerator should be set at 4.44 deg C, while the freezer should be kept at -17.7 deg C.”
Prepare food properly
Wash your hands before and after handling raw meat and poultry. Food should also be prepared on clean surfaces using clean utensils. After cutting raw meat, wash hands, counter tops and utensils with hot, soapy water.
Never leave food out in the open for more than two hours. Bacteria that cause food poisoning will multiply rapidly at room temperature. “When in doubt, discard the food,” said Dr Wijaya.