Foodborne Disease

Last updated: 06 February 2008

What is foodborne disease?

Foodborne disease (or food poisoning) results from consuming contaminated food or drink. It is very common, with an estimated 5.4 million cases per year in Australia.

Three main types of agents may cause illness from food:

• bacteria
• viruses
• toxins in food (either naturally occurring or introduced to a food).

What are the symptoms?

Different symptoms can result from eating contaminated food. Common causes are:

• bacteria, e.g., Salmonella, Campylobacter and Listeria
• viruses, e.g., norovirus and hepatitis A
• toxins, e.g., toxins made by bacteria such as Staphylococcus aureus or Bacillus cereus

Symptoms will vary, depending on the cause. They may include:

• diarrhoea
• vomiting
• nausea
• abdominal pain
• fever.

Other symptoms may include:

• headache
• jaundice
• numbness.

Symptoms can take between a few hours to a few days, or even longer, to develop and usually last for a few days, sometimes longer.

How is it spread?

Foodborne illness is mainly spread to humans when they eat poorly cooked food made from infected animals (that is, meat, poultry, eggs, and their by-products). Spread by 'cross-contamination' occurs when Salmonella contaminates ready-to-eat food: for example, when food that will not be cooked further is cut with a contaminated knife or via the hands of an infected food handler. Foodborne illness can spread from person-to-person via the hands of an infected person. It can also be spread from animals to humans.

Who is at risk?

Anyone can get a foodborne disease. However some people are at increased risk of serious illness. These include:

• infants
• elderly
• people with suppressed immune systems
• pregnant women.

How is it prevented?

Hygiene
Wash your hands thoroughly with soap and running water for at least 10 seconds and dry them with a clean towel after using the toilet, changing nappies, and before eating or preparing food. People with symptoms of foodborne disease should not prepare food for others. People who have symptoms of foodborne disease and work as food handlers or who care for patients, children or the elderly should not work for 48 hours after symptoms have resolved.

Temperature control
Poor food storage can allow Salmonella to grow. Refrigerated food should be kept at less than five degrees Celsius. Hot foods should be kept hot at above 60 degrees Celsius. Reheated foods should be quickly reheated until all parts of the food are steaming hot. Thawing frozen foods should be done in a fridge or microwave. The longer you leave food at room temperature the more Salmonella can multiply.

Food contamination
To prevent the contamination of food:

• store raw foods (such as meat) in sealed containers in the bottom of the fridge or freezer to prevent any fluid dripping or spilling onto other ready-toeat food. Cover all foods in the refrigerator and freezer to protect them from contamination
• wash hands immediately after going to the toilet or handling raw foods and before handling cooked or ready-to-eat food
• use different chopping boards, trays, utensils and plates when preparing raw foods and ready to eat food. If you have only one chopping board wash it well in hot soapy water before reuse
• thoroughly wash all dirt off any raw vegetables and fruits before preparing and eating them
• dry dishes with a different cloth to that used for wiping hands or bench tops; wash dish cloths regularly.

How is it diagnosed?

A diagnosis of foodborne illness is based on a person's symptoms. Laboratory confirmation is important during outbreaks and includes testing samples of stools.

How is it treated?

Many people have mild symptoms and will soon recover. People with diarrhoea and vomiting should stay home from work or school and drink plenty of fluids. People at risk of dehydration such as infants and the elderly should see their local doctor early. Antibiotics are not usually required except in complicated cases.

What is the public health response?

Laboratories are required to notify cases of Salmonella infection to the local public health unit. The public health units investigate clusters of casess to try and identify common links. Where a common food is implicated the NSW Food Authority will undertake a further environmental investigation and initiate control measures. Statistics on cases are used to help develop prevention strategies.

The NSW Food Authority is responsible for a range of food safety strategies to prevent salmonellosis and other food borne infections.

For more information

• Oz FoodNet Outbreak Summary Form  /resources/publichealth/infectious/diseases/ozfoodnet_outbreak_sum_pdf.asp
• Oz FoodNet Reports - Methods  /resources/publichealth/infectious/diseases/ozfoodnet_methods_pdf.asp
• Oz FoodNet 4th Quarterly and Annual reports 2007  /resources/publichealth/infectious/diseases/nsw_ofn_4q_and_annual_2007_pdf.asp
• Environmental Investigation Form  /resources/publichealth/infectious/diseases/enviromental_investigation_form_pdf.asp
• Guidelines to Envoronmental Investigation Form  /resources/publichealth/infectious/diseases/eif_guidelines_pdf.asp
• NSW Food Authority  http://www.foodauthority.nsw.gov.au/