Food Poisoning (Foodborne Illness)

Food poisoning is estimated to affect over 4,000,000 Australians every year, resulting in about 31,000 hospitalisations and 86 deaths annually (Food Safety Information Council 2022).

Despite these alarming statistics, many cases of food poisoning are actually easily preventable (AIFS 2018).

What is Food Poisoning?

Foodborne illness, colloquially known as food poisoning, is an umbrella term describing the range of illnesses that can occur after ingesting contaminated foods and drinks (Food Authority 2020a).

Food poisoning occurs when an individual consumes food containing harmful viruses, bacteria or toxins and consequently becomes unwell (Healthdirect 2021).

Despite being extremely common, food poisoning has the potential to cause serious illness and even death, especially among vulnerable populations such as older adults, young children, pregnant people and those with pre-existing chronic conditions (Health.vic 2022).

What Causes Food Poisoning?

Pathogens and toxins are inherently present in the natural environment. Bacteria, for example, can be found in soil, animals and humans - even those who are healthy. Products such as meats and vegetables often naturally contain bacteria that are harmless in small amounts but can become more dangerous if left to multiply (Health.vic 2022).

Certain pathogens and toxins are more likely to cause illness than others. This is because they:

• May be hard to detect
• Are easily transferred between humans, animals, pests and raw produce
• Grow rapidly in ambient room temperatures or water (e.g. Bacillus cereus)
• Can potentially survive or regenerate even after control steps such as cooking have been taken.

(Ausmed 2022; ABC Everyday 2019)

Pathogens and toxins that commonly cause food poisoning include:

• Bacillus cereus
• Campylobacter
• Clostridium perfringens
• Clostridium botulinum
• Hepatitis A and E viruses
• Listeria
• Norovirus
• Rotavirus
• Escherichia coli (E. Coli)
• Salmonella
• Shigella
• Staphylococcus aureus.

(Food Standards Australia & New Zealand 2021; Ausmed 2022)

There are certain foods that are more likely to become contaminated because they either contain pathogens that could become dangerous if left to multiply or provide an ideal environment for harmful pathogens to grow and thrive. These potentially hazardous foods include:

• Meat and meat-containing foods
• Smallgoods
• Unpasteurised milk and dairy foods
• Seafood
• Processed or cut fruits and vegetables, such as pre-prepared salads
• Foods containing protein-rich ingredients like eggs, beans and nuts
• Rice
• Food that contains any of the above ingredients, such as sandwiches.

(Ausmed 2022; Ross 2019)

Certain sources of food poisoning, such as poisonous mushrooms, are dangerous to ingest regardless of how they are prepared (Healthdirect 2021).

It’s important to remember that food doesn’t necessarily need to smell, look or taste bad to be contaminated. Most cases of food poisoning are caused by food that seems perfectly inconspicuous. This is why taking appropriate food safety measures is crucial in preventing illness (Food Authority 2020b).

How Does Food Become Contaminated?

The way in which food poisoning occurs can be described by the ‘food poisoning chain’:

1. Pathogens or toxins are present in the food.
2. The pathogens or toxins are provided with the right conditions required to grow: temperature, moisture and a food source.
3. The pathogens or toxins are given adequate time to grow and multiply.

If any of the links in this chain are broken, food poisoning can be prevented (Health.vic 2022).

Examples of breaking the chain include ensuring food is cooked at a high enough temperature to kill pathogens, storing food at a safe temperature and eating food as soon as it has been cooked.

Ways in which food can become contaminated by harmful pathogens and toxins include:

• Poor preparation (e.g. undercooking meat)
• Food being handled without prior handwashing
• Food being handled by an unwell person
• Food being touched by pets, flies, insects etc.
• Cross-contamination (e.g. using a chopping board for raw meat that is then used for cooked meat without being washed in between)
• Unsafe food storage (e.g. storing food at temperatures that allow bacteria to grow and multiply)
• Fruit, vegetables and eggs coming into contact with animal manure
• Letting food progress past its ‘use-by’ date.

(Healthy WA 2018; Food Authority 2020a)

Symptoms of Food Poisoning

Food poisoning typically causes symptoms such as:

• Nausea
• Vomiting
• Diarrhoea
• Abdominal pain
• Fever
• Headache
• Flu-like symptoms.

(Better Health Channel 2021; Healthdirect 2021)

The most common complication of food poisoning is dehydration, which can occur if the individual loses more fluids than they can replace due to vomiting and diarrhoea. In severe cases, dehydration may require admission to hospital and intravenous fluid replacement (Mayo Clinic 2020).

Depending on the cause of the food poisoning, the individual might also be at risk of other potentially severe complications. For example:

• Listeria infection may lead to a miscarriage or pregnancy or birth complications
• Listeria infection may result in meningitis
• E. coli infection may cause haemolytic uraemic syndrome, which can lead to kidney failure.

(Mayo Clinic 2020; Better Health Channel 2021)

The onset of symptoms depends on the underlying cause of the food poisoning. For example, Salmonella infection can cause symptoms after as little as eight hours, while Listeria infection can take up to 70 days to cause illness (Healthdirect 2021).

For this reason, it can’t be assumed that food poisoning is caused by the most recent food consumed (Food Authority 2020b).

Treatment for Food Poisoning

Most cases of food poisoning resolve on their own after one to two days, but certain infections (e.g. E. coli, hepatitis A) may persist for longer (Food Safety Information Council 2021).

Mild cases can typically be managed at home using strategies such as:

• Sucking on ice chips for fluid intake
• Using an oral rehydration solution to replenish lost fluids
• Easing back into a normal diet and routine.

(Healthdirect 2021)

When to Escalate Care

While many people who experience food poisoning don’t require medical intervention, it can be a serious illness. Signs that care should be escalated include:

• Patient under 12 months of age
• Symptoms that have lasted for more than three days, or are extremely severe
• Signs of severe dehydration (e.g. inability to keep fluids down, little or no urine output, weight loss, fatigue, extreme thirst)
• Blood or mucus is present in vomit or diarrhoea
• Fever of over 38.6°C
• Blurry vision, muscle weakness or tingling in arms.

(Healthdirect 2021; Food Safety Information Council 2016)

Preventing Food Poisoning

For comprehensive guidance on how to prevent food poisoning, see the Ausmed Training Module on Food Safety in Residential Aged Care.