Tuesday 20 March 2018

Hygiene and cooking key to avoiding food poisoning

The peak time for salmonella was June and July, the months when people travel abroad. Photo: Getty Images/iStockphoto
The peak time for salmonella was June and July, the months when people travel abroad. Photo: Getty Images/iStockphoto

Dr Nina Byrnes

MY DAUGHTER contracted food poisoning last year and ended up very sick in hospital. Thankfully she is ok now, but what do I need |to know about food poisoning and how can I avoid it?

ILLNESS that occurs after eating or drinking food contaminated with harmful bacteria or bacterial toxins is known as ‘Food Poisoning’. People often assume that this can occur due to eating food that was ‘off’ or unusually contaminated, but the fact is foodborne illness can occur after eating many common foods.

There are over 250 types of foodborne disease. Most of these are bacteria, viruses or parasites that cause infection; others are toxins or chemicals that are contained in food or contaminate them. Certain foods such as dairy, meat, poultry and shellfish are particularly attractive to bacteria.

There are certain conditions that encourage the growth of bacteria on food. A temperature between 5 and 63 degrees centigrade is the optimum temperature for bacteria to grow. A single bacterium can multiply to over two million in seven hours, so food left lying around can become a source of infection. Foods that contain moisture, such as soups, sauces, dressings, and sandwich foods, are also more likely to grow bacteria.

Most foodborne illness enters the body when food is ingested. However, some other foodborne bacteria can spread in other ways. E coli 157, which can cause serious foodborne illness, also spreads through contaminated drinking or swimming water, through contact with animal or human faeces (such as when changing nappies) and amongst toddlers in close contact, such as in crèches or playgroups. Another source may be close contact with animals through a commercial or petting farm.

The most common symptoms of foodborne illness are nausea, vomiting, abdominal cramps and diarrhoea and, less commonly, fever and headaches. In the majority of cases the illness lasts one to three days and passes easily. However, in rarer cases, serious illness or even death can occur.

Salmonella is a bacterium commonly found in the intestines of humans and animals. It is also found in raw meats, poultry, eggs and unpasteurised milk. Most people infected with Salmonella will develop cramps, diarrhoea and fever within 72 hours of eating contaminated food. The illness usually lasts between four and seven days. If severe diarrhoea occurs, admission to hospital may be required. This is more likely in young children, the elderly or in those with weaker immune systems due to medication or illness.

Most people recover quickly but it may take a few months before bowel motions return completely to normal. A rare complication is pain in the joints, irritation of the eyes and pain passing urine. Antbiotics are sometimes prescribed in more severe cases.

E coli 157 is a member of the E coli family, a large group of bacteria of which many are harmless but some have the potential to cause illness. E coli is one of the more common causes of urinary tract infections. Ecoli 157 is a potentially life threatening cause of foodborne illness. This bacterium produces a toxin that makes it more dangerous than other milder strains. E coli is found in the gastrointestinal tract of warm blooded animals. It is transmitted to humans mainly through the ingestion of raw or undercooked meat, unpasteurised milk and raw vegetables that may have been exposed to animal manure during the growing process.

Most people develop abdominal cramps and diarrhoea within three to four days of ingesting the bacteria. The illness usually passes off within  10 days. In more severe cases diarrhoea may contain blood and last longer. Those with severe abdominal cramps or severe diarrhoea should attend a doctor. These people are at risk of a condition called Haemolytic Uraemic Syndrome which can result in kidney failure, clotting problems and death. It is estimated that up to 10% of those infected with E coli 157 may develop this complication.

As with many illnesses, prevention of foodborne disease is better than cure. Regular handwashing both before and after preparing or consuming food, after using the toilet or changing nappies, and after contact with animals is key in preventing the spread of these infections. This is particularly important in children and the elderly who are particularly at risk of more serious complications of foodborne illness.

Food should be cooked thoroughly and the centre heated to at least 70 degrees centigrade. Make sure to wash raw vegetables thoroughly or peel prior to eating them. Avoiding raw or undercooked meats and unpasteurised milk or milk products is also important. Chill food to less than 5 degrees prior to cooking to reduce the growth of bacteria. Always keep raw and cooked meats separate and don’t use the same cooking utensils or plates for raw and cooked food.

If you are unfortunate enough to become unwell, drink plenty of water and, if you must eat, stick to bland food such as plain crackers, rice or toast. If you have severe symptoms such as severe pain, persistent fevers, prolonged illness or are passing blood, seek the attention of a doctor.

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