Food poisoning is the name for the range of illnesses caused by eating or drinking contaminated food or drink. It is also sometimes called foodborne illness. The most common symptoms of food poisoning include nausea, vomiting, and diarrhoea.
It’s quite uncomfortable, and unfortunately quite common, affecting an estimated 4.1 million Australians each year. Symptoms are often unpleasant and for some groups they can be quite serious.
Here are some of the ways your food can become contaminated.
Salmonella
In Australia, salmonellosis tends to be more prevalent in the warmer months. Eating food that has been kept in the temperature danger zone for too long allowing the bacteria to grow is often the cause of the illness.
Cold food needs to be kept below 5°C and hot food at 60°C or above. If food is kept outside these temperatures for more than four hours, it’s advised to throw it away.
Salmonellosis symptoms usually start 12–36 hours after eating contaminated food and common symptoms include diarrhoea, cramps, nausea, vomiting, fever and headaches.
Eggs and poultry
Salmonella bacteria can contaminate any food but products from animals are more like to become infected due to the higher possibility of contact with animal faeces.
Eggs can be infected before the shell forms so even clean, fresh eggs can cause food poisoning.
Raw fruit and vegies
Fresh produce can harbour salmonella usually transferred from contaminated soil or water, for example from exposure to animal manure, sewerage or dirty hands during the growing and harvesting process.
Ensure you wash raw fruit and vegetables thoroughly in running water and avoid cross-contamination. Use separate cutting boards and knives for raw chicken and ready-to-eat food. Store cooked food separately from raw foods.
Processed foods
You probably think you’re safe from salmonella when reaching for a packet of crackers or tub of peanut butter. However, processed foods such as these have been recalled due to salmonella concerns, even frozen meals may pose a slight risk for salmonella infection.
Never use a product that has been recalled – immediately return it to the store or throw it away.
Raw meat
Ensure all meat is cooked completely to a safe temperature. Ground meat is a particular risk for salmonella contamination as it typically looks and smells normal when infected.
Read: Things to know before reheating food
E. coli
Many strains of E. coli are found naturally in the gut of humans and animals where they may be harmless unless they find their way into other body sites or wounds. However, particular strains are known to make people sick and some are a common cause of traveller’s diarrhoea and diarrhoea in infants in developing countries. The illness typically develops several days after exposure and can be severe in vulnerable people.
Minced beef
E. coli lives in the intestines of cattle and can contaminate beef during the slaughtering process. Minced beef is especially risky, because the bacteria can spread when meat is ground up.
Raw juice and milk
Since most juices you’ll find at the supermarket will have been pasteurised, they pose no risk as pasteurisation uses heat to kill bacteria.
However, unpasteurised juices and other drinks sold at farms, stands, or in health food stores, can harbour E. coli. The bacteria can also get into raw milk as a result of unclean milking equipment, or manure-soiled or infected udders.
Fresh produce
If fertiliser or water used during the growing process is contaminated with E. coli it could be passed on to the produce. Leafy greens are at the highest risk but there are now plenty of safety measures in place to minimise the risk. Experts say the health benefits of eating fruits and vegies are far greater than the risk of food poisoning.
Separate and individually wash the leaves of leafy greens, and cook vegetables to kill bacteria.
Read: The science of food allergy and intolerance testing
Botulism
Botulism is an illness caused by a toxin produced by Clostridium botulinum bacteria. These spores are naturally present in the environment, often living in garden soil.
The condition is potentially fatal and causes progressive and often rapid weakness, but fortunately, it is very rare.
In Australia, there is typically only one case of botulism reported per year.
Foods such as honey, fermented, home preserves, or salted or smoked fish or meat are the most common causes of botulism.
Clostridium perfringens (C. perfringens)
These bacteria are widespread in the environment and in the gut of people and animals but can cause cramps and diarrhoea if spores and toxins are not destroyed by thorough cooking.
Meat, stews, and gravies
Stews, gravies, and other foods that are prepared in large quantities and kept warm for a long time before serving are a common source of C. perfringens infections.
Serve food hot right after cooking and promptly refrigerate leftovers in shallow containers to allow for proper cooling.
Campylobacter
Campylobacteriosis is a gastrointestinal disease caused by bacteria called Campylobacter. In Australia, infection can occur at any time of the year, but is more common in the warmer months.
Undercooked poultry
As little as one drop of raw chicken juice can cause Campylobacteriosis.
Symptoms can include fever, cramps, watery or often bloody diarrhoea, and vomiting. Most people recover in less than a week, but it can lead to Guillain-Barre syndrome, a rare, serious illness.
Avoid cross-contamination by washing hands, cutting surfaces, utensils, and countertops in warm, soapy water after handling raw poultry. Cook poultry to at least 74°C.
Norovirus
Norovirus infections are highly contagious and are a leading cause of gastroenteritis in Australia and worldwide.
Good hygiene is very important. Wash food before eating, especially oysters and shellfish, and fruits and vegetables. And wash hands with soap and water before eating or handling food to help prevent infection.
Read: Surprising foods that give you food poisoning
Listeria
Listeriosis, is a rare but serious disease caused by the bacteria Listeria monocytogenes (L. monocytogenes) that can survive and grow on certain high-risk foods. While it is probably common for people to eat foods contaminated with a small amount of the bacteria, only some people are at risk of becoming sick. The people who do get sick may require hospitalisation and it may lead to death.
Foods that have a higher risk of L. monocytogenes contamination include:
- chilled seafood such as raw oysters, sashimi and sushi, smoked ready-to-eat seafood and cooked ready-to-eat prawns
- cold meats from delicatessen counters and sandwich bars, and packaged, sliced ready-to-eat meats
- cold cooked ready-to-eat chicken (whole, portions, or diced)
- rockmelon
- pre-prepared or pre-packaged fruit or vegetable salads, including those from buffets and salad bars
- soft, semi-soft and surface-ripened cheeses such as brie, camembert, ricotta, blue and feta
- refrigerated pâté or meat spreads
- soft-serve ice cream
- unpasteurised dairy products
- raw mushrooms.
Have you ever had food poisoning? Were you aware so many different viruses and bacteria could cause food poisoning? Let us know in the comments section below.
Health disclaimer: This article contains general information about health issues and is not advice. For health advice, consult your medical practitioner.
