Updated 1 December 2020

Food Poisoning

Food Poisoning

Introduction

Food poisoning is caused by the ingestion of any food or drink which is contaminated with certain types of viruses, bacteria, parasites or toxins. Some people are more prone to getting food poisoning such as young children, the very old, women who are pregnant, and people with weaker immune symptoms.

Contamination of food

 Common ways food gets contaminated are as follows:
  • When food is handled by someone who has gastroenteritis (or gastro)
  • When the meat is undercooked or handled without the washing of hands prior
  • When raw meats come into contact with other ready to eat foods
  • When food is stored at unsafe temperatures which allows bugs to grow
  • When there is contact with animals or pests such as flies

The Symptoms of Food Poisoning

The type and severity of the symptoms experienced by sufferers of food poisoning usually depend on the cause of the condition. Also, the time it takes for the symptoms to show up depends on what causes food poisoning to begin with. However, whatever the source of the condition may be, the time that it takes for symptoms to manifest usually ranges from as soon as 6  hours to about 6 days in most cases. Typically, regardless of the source of the food poisoning, symptoms can include some or all of the following;
  • Nausea,
  • Vomiting,
  • Diarrhea,
  • Belly cramps, aches, and pains,
  • Sweating, fever or chills
  • A loss of appetite,
  • Headaches,
  • Tiredness
The symptoms of food poisoning are often the same as the symptoms of viral gastro that is more often due to contact with another ill person (person to person spread) or contaminated surfaces.

Causes of food poisoning

There are many bacteria, viruses and parasites which can cause food poisoning. The table below outlines some of these and how long before you start to get symptoms after eating the contaminated food and the types of food associated with each.  
Bug causing the contamination Common time taken for onset of symptoms after ingestion -of contaminated food Food affected
Salmonella 12-72 hours Raw meat and poultry, undercooked eggs
Norovirus 12-48 hours Mainly person to person spread. Also ingesting contaminated food or drinks, placing contaminated hands or fingers into mouth or sharing food or eating from the same utensils as someone who is ill.  
Rotavirus 1-3 days As for Norovirus
Campylobacter 2-5 days Meat and poultry, contaminated water or unpasteurised milk.
Giardia lamblia 7-10 days Uncooked food, fruit and vegetables, contaminated water
Escherichia coli (E coli) 1-8 days Undercooked beef, unpasteurised milk, contaminated water, alfalfa sprouts.
Hepatitis A 28 days Contaminated food and drink, fish from contaminated water.
Listeria 2 days to 3 months Ready to eat deli meats, unwashed raw produce, unpasteurized milk, soft cheeses
Shigella 1-3 days Contaminated food and drink. Person to person spread.
Staphylococcus Aureus 1-6 hours Processed meat, raw meat and poultry, cheese, cream and unpasteurised milk
Clostridium perfringens 8-20 hours Meat and poultry. Commonly spreads when serving dishes are not kept hot enough or food is chilled too slowly.
 

Food Poisoning Treatments

Most cases of food poisoning are mild and home care may be effective in most cases. Keeping hydrated is absolutely crucial to the treatment and the rate of recovery of the patient. Sucking ice chips is highly recommended. You can replace lost fluids and electrolytes by buying an oral rehydration solution from a pharmacy. Once you start to feel better, you may ease back to your normal diet and routine. It is important that you do not handle or prepare food for others until you are symptom-free for 48 hours to prevent passing on your condition to others. If you must handle food wash your hands thoroughly with soap and water and then dry them to prevent cross-contamination. People in the high-risk group such as the elderly, young children, women who are pregnant, or people with weakened immune systems should see a doctor early on to prevent complications such as dehydration. You should also see a doctor if any of the following occurs:
  • If you have severe symptoms
  • If symptoms have been present for more than 3 days
  • You can't keep fluids down
  • If there is any blood or mucous in your vomit or diarrhoea

Food poisoning complications

Dehydration is the most common serious complication of food poisoning. This is caused by a severe loss of water, salts, and minerals from the body. If you are able to drink enough fluids to replace the loss from vomiting and diarrhoea then the risk is reduced, especially if you are a healthy adult. Dehydration may require hospitilisation and the administration of intravenous fluids as, in extreme cases, dehydration may be fatal. There are 2 types of food poisoning which require special mention due to potentially serious complications in certain people:
  • Listeria food poisoning may be more severe for the unborn baby. In early pregnancy, Listeria infection can cause miscarriage while in later pregnancy it may lead to stillbirth, premature birth, or a serious potentially fatal infection in the baby after birth.
  • Some Escherichia coli strains can cause hemolytic uremic syndrome (HUS) which damages the kidneys and sometimes causes kidney failure. This seems to be more common in children under 5 years of age, older adults, and people with weakened immune systems. A key symptom of this condition is diffuse or bloody diarrhoea.

Prevention of food poisoning

Here are some tips to reduce your risk of catching or spreading food poisoning
  • Wash your hands regularly after changing nappies, using the toilet, before eating and when preparing food
  • Wash food utensils, cutting boards and surfaces often
  • Keep raw meat, poultry, fish and shellfish away from other foods to prevent cross-contamination.
  • Cook foods to a safe temperature to kill harmful organisms.
  • Place perishable foods in the fridge or freezer within 2 hours of purchasing or preparing them. This should be 1 hour if the room temperature is above 32 degrees Celsius.
  • Defrost foods safely via the refrigerator rather than room temperature.
  • When not sure whether a food has been prepared, stored, or served correctly, throw it out
  • If you have food poisoning, stay home away from work, school or others until you have no symptoms for 48 hours so you do not spread the condition.
  • When travelling, if the local tap water is unsafe, only use bottled water for drinking or brushing your teeth. Also do not put ice in your drinks, only eat fruit you can peel yourself, and avoid uncooked foods such as salads.