Food Safety: The Bugs
How to keep yourself and your food safe
A wide variety of micro-organisms – bacteria, fungi, parasites, viruses and other organisms – can cause illness in people. Many of these can contaminate food. Knowing what to watch out for and how to ensure you don’t contaminate food that you, your family or others are going to eat is an important part of knowing how to avoid foodborne illness. It can take from as little as 20 minutes to several weeks to become sick from food that’s been contaminated by pathogens (and your illness may not be caused by the last thing you ate). Foodborne illness can be mild but sometimes (especially if you have low immunity) it can be life-threatening or cause death. If you think you have an illness caused by food, contact your doctor right away.
More information about pathogens that cause foodborne illnesses
Name | Possible symptoms (from most to least common) | Foods and causes linked to outbreaks | How soon it typically strikes |
Bacillus cereus (bacteria) | Two different forms of foodborne illness: Vomiting, nausea, occasional diarrhoea Diarrhoea, abdominal pain, occasional nausea | Rice, starchy foods such as potato and pasta, meat, casseroles, vegetable dishes, foods containing spices | 1 to 6 hours (vomiting) 10 to 12 hours (diarrhoea) |
Campylobacter (bacteria) | Muscle pain, headache, fever, followed by diarrhoea (can be bloody), abdominal pain, nausea | Undercooked chicken, unpasteurised milk, chicken liver pâté, drinking water | 2 to 5 days but can range from 1 to 10 days |
Ciguatera (toxin) | Nausea, vomiting, diarrhoea, muscle pain followed by neurological symptoms including headache, temperature reversal (hot things feel cold and cold things feel hot), dizziness, tingling, muscular weakness, irregular heartbeat | Grouper, barracuda, snapper, jack, mackerel, triggerfish (caught in tropical regions) | Within 6 hours |
Clostridium botulinum (bacteria) | Nausea and vomiting followed by neurological symptoms including weakness, dizziness, double vision, difficulty speaking, swallowing and breathing, abdominal distension | Canned or bottled foods, especially vegetables and seafood products, garlic in oil | 12 to 36 hours |
Clostridium perfringens (bacteria) | Severe abdominal pain, watery diarrhoea, occasional vomiting and nausea | Meat dishes, especially rolled roasts, stuffed meat, soups, stews, gravies, pies | 10 to 12 hours, but can range from 6 to 24 hours |
Cryptosporidium parvum (parasite) | Watery diarrhoea, vomiting, stomach cramps, weight loss | Drinking water, raw fruits and vegetables, apple juice, unpasteurised milk, salads | 3 to 11 days |
Cyclospora (parasite) | Watery diarrhoea, loss of appetite, weight loss, cramps, nausea, vomiting, muscle aches, low grade fever, extreme fatigue | Raspberries, lettuce, basil and pesto | 1 week |
E.coli (0157:H7) (bacteria) | Severe abdominal pain, watery (then bloody) diarrhoea, occasional vomiting | Undercooked minced meat, unpasteurised milk, lettuce, sprouts, unpasteurised fruit juices | 1 to 8 days |
E. coli (STEC) (bacteria) | Range from mild diarrhoea through severe cramps to profuse diarrhoea containing a lot of blood | Undercooked minced meat, cooked meat, apples, radishes, unpastuerised juices and dairy products, direct contact with animals and animal fertiliser, contaminated water | 1 to 2 days |
Giardia intestinalis (parasite) | Diarrhoea, flatulence, stomach cramps | Raw vegetables, drinking water, salads, fruit salad, sandwiches | 1 to 3 weeks |
Hepatitis A (virus) | Fever, malaise, nausea, vomiting, loss of appetite, abdominal pain, jaundice | Shellfish, salads, cold meats, sandwiches, fruits, vegetables, fruit juices, milk, milk products, infected food handlers | 10 to 50 days |
Listeria (bacteria) | Non-invasive: Diarrhoea, fever, muscle pain, headache, occasional abdominal cramps and vomiting Invasive: Fever, headache, diarrhoea, vomiting, septicaemia, encephalitis,meningitis, spontaneous abortion or stillbirth | Long shelf-life products stored under refrigeration such as deli meat and poultry products, smoked seafoods, cheeses (particularly soft ripened cheeses), pre-cooked sausage products. Also unpasteurised milk, corn salad, coleslaw | Non-invasive: 11 hours to 7 days Invasive: 1 day to 3 weeks |
Norovirus (virus) | Nausea, vomiting, diarrhoea, abdominal pain, headache, low-grade fever | Shellfish, salads, sandwiches, cold meats, infected food handlers | 24 hours but can range from 10 to 50 hours |
Salmonella(bacteria) | Nausea, vomiting, abdominal cramps, diarrhoea, fever, headache | Raw meats, poultry, unpasteurised milk and dairy products, seafoods, fresh produce (including sprouts), foods handled by infected foodhandlers, eg kebabs, sandwiches | 6 hours to 2 days |
Scombrotoxin (toxin) | Tingling or burning sensation in the mouth, upper body rash, reduced blood pressure, headache, itching, nausea, vomiting, diarrhoea | Fresh tuna, kahawai, mahi mahi, bluefish, sardines, mackerel, amberjack, abalone | A few minutes to a few hours |
Staphylococcus aureus (bacteria) | Nausea, vomiting, abdominal cramps, occasional diarrhoea | Ham, cooked meats, yoghurt, chicken salad, pasta dishes, bakery products (especially cream-filled), cheese | 2 to 4 hours but can range from 30 minutes to 7 hours |
Vibrio parahaemolyticus (bacteria) | Diarrhoea, abdominal pain, nausea, vomiting, headache, fever, chills | Raw oysters and clams, crabs, shrimp | 4 hours to 4 days |
Vibrio vulnificus (bacteria) | Diarrhoea (in healthy people), bloodstream infection (in people with liver disease, diabetes, or weak immune systems) | Raw oysters and clams, crabs | Within 16 hours (diarrhoea) |
Yersinia enterocolitica (bacteria) | Adults: Abdominal pain, headache, fever, diarrhoea, nausea, vomiting Children: Watery, mucoid diarrhoea | Pork and pork products, dairy products, fruit, vegetables, tofu | 7 days but can range from 1 to 11 days |