Information about common foodborne illnesses including salmonella, campylobacter, and E.coli, and how to protect yourself.
Salmonella and salmonellosis
In 2006, a total of 1335 individuals were reported with Salmonella infection, a rate of 32.3 per 100,000 population, this is a similar rate to that reported in 2005.
Age groups most likely to be affected with Salmonella were:
- infants less than one year of age (83 cases reported and an age specific rate of 145.3 per 100,000)
- young children age one to four years (280 cases, and rate of 124.2 per 100,000)
- adults age 20 to 29 years,(185 cases, 33.5 per 100,000).
Although information is incomplete, individuals identified the following exposures as risk factors for Salmonella infection:
- consuming food from retail premises
- contact with farm animals
- consuming untreated water
- travelling overseas during the incubation period
- contact with other symptomatic people or contact with faecal matter
- contact with recreational water.
Campylobacter means ’curved rod‘ in Greek, which refers to the shape of these bacteria. Each one is a slender, spiral-shaped rod, only 1.5 to 3.5 micrometres long – a micrometer is just a thousandth of a millimetre!
Each bacteria has a tail, known as a flagellum, at each end of the cell.
In 2006, there were 15,873 individuals reported with Campylobacter infection, a rate of 383.5 per 100,000 population, this was a significant increase from the rate of reported disease in 2005, (a rate of 337.6 per 100,000 in 2005).
The age groups most commonly infected were:
- young children age one to four years (1227 cases and an age specific rate of 544.2 per 100,000)
- adults in the 20-29 year age group (2884 cases, 522.7 per 100,000)
- infants under one year of age (237 cases, 415.0 per 100,000).
Not all cases of campylobacter are followed up by public health services and therefore risk factor information is far from complete. Consuming food from retail premises and contact with farm animals were the most frequent risk factors identified.
Verotoxin-producing E. coli (VTEC) & HUS (Haemolytic Uraemic Syndrome)
E. coli are common germs (bacteria) normally found in the gut of warm blooded animals and people. There are many types of E. coli, most of which are harmless. However, some types can produce poisons (toxins) which can cause stomach upset and illness. One type of these E. coli are known as Verotoxin-Producing E. coli or VTEC.
What illness is caused by VTEC?
VTEC most commonly causes diarrhoea, which can range from mild to severe. It may be bloody, and accompanied by stomach cramps. Symptoms are generally mild in healthy people, however, they can be severe in children, the elderly, and people with reduced immunity.
What is HUS?
Haemolytic Uraemic Syndrome (HUS) is a rare condition affecting the kidneys and the bloodstream, and can be caused by VTEC. This condition leads to kidney problems, anaemia and sometimes death.
It usually takes up to a week after the bacteria are taken in by mouth for the first symptoms to appear.
How is VTEC spread?
Illness due to VTEC occurs when food and water containing E.coli bacteria are taken in by mouth. This may happen in any of the following ways:
Inadequate Cooking, cross contamination of food or person to person spread through poor hygiene.
What precautions prevent its spread?
- Careful, frequent and thorough handwashing with soap and drying hands
- Safe food storage and handling including ensuring food is thoroughly cooked
- Avoid or boil water from untreated sources such as rivers or streams
- Keep pets out of the kitchen or wash hands after handling them.
How many cases are there in New Zealand?
VTEC is a notifiable disease in NZ. In 2010 there were 138 cases of VTEC in New Zealand; 32 cases of HUS and no fatalities. Note: These are not of the same strain causing disease in Germany.
What VTEC Testing is done in New Zealand?
In New Zealand screening for VTEC is done by community laboratories. Positive cases are confirmed by testing at ESR. ESR is able to test for the strain causing disease in Germany - no cases of which have been reported in New Zealand.
Key ways to protect against foodborne illness
When to be extra careful
Foodborne diseases are more common in summer and people need to be especially aware of the extra care they should take with the food they prepare and eat. Warmer temperatures allow bacteria to multiply faster on contaminated food resulting in larger doses of bacteria if the food is not properly cooked before being eaten.
1) Reduce bacterial contamination and growth:
- store foods at an appropriate temperature out of the 'danger zone' (between 4 deg C and 65 deg C - ie fridge and steaming hot)
- do not leave perishable food at room temperature for more than a total of two hours
- cook and reheat foods, especially meat and poultry, so they are piping hot throughout
- use cooked foods, that have been stored in the refrigerator, within two days
- never reheat food more than once
- wash all fruit and vegetables thoroughly
- freeze foods quickly, thaw in the refrigerator or microwave, avoid re-freezing thawed foods
2) Protect food from cross-contamination through appropriate storage, handling and sanitation:
- keep raw and prepared foods separate during preparation, serving and storage
- store prepared foods above raw foods in the refrigerator
- store foods in covered containers whether in the fridge or the cupboard
- keep food storage, preparation areas and equipment clean using hot soapy water. It is a good idea to have separate cutting boards for raw foods such as meat and poultry, and ready to eat foods such as cheese, cooked meats and salads.
3) Ensure good personal hygiene:
- ensure adequate personal hygiene including hand washing after handling raw foods, refuse, animals, visiting the toilet or changing nappies
- do not cough or sneeze over food
- do not smoke when preparing food (handling cigarettes puts saliva and bacteria from skin or lips onto your hands which may then contaminate the food)
For more information on food safety and foodborne illnesses, go to the Ministry for Primary Industries website.