Many people pass the symptoms off as stomach flu. All of us, at one time or other, have probably had a foodborne illness. Symptoms may be mild and disappear in a few hours or days. In severe cases, a stay in hospital may be needed. Death may even result, especially in the very young and the elderly.

What causes food-borne illness?

Food poisoning occurs when food is eaten which contains enough germs (bacteria, bacterial toxins or viruses) to cause illness. The most common food poisoning bacteria and viruses are listed in Table 1.

Common food poisoning bacteria and viruses
Name of Organism	Undercooked chicken, turkey, eggs, neat	6-72 hours	abdominal cramps, diarrhea, fever, chills, vomiting
Salmonella	Undercooked ground beef	12-72 hours	abdominal cramps, bloody diarrhea, fever, vomiting
E. coli 0157-H7 (causes 'hamburger disease')	Undercooked chicken or hamburger; unpasteurized milk; contaminated water	1-10 days	Nausea, cramps, headache, fever, diarrhea
Clostridium perfringens	Stews, meat pies, meat gravies held at improper temeratures	6-24 hours	Cramps, nausea, diarrhea
Staphylococcus aureus (toxin produced by this bacteria causes illness)	Cooked ham, potato salad; inadequately reheated leftovers	1-6 hours	Nausea, vomiting, abdominal cramps, diarrhea
Norwalk virus	Food contaminated by someone with the disease	10-50 hours	Nausea, vomiting, abdominal cramps, diarrhea, fever

Once the food containing bacteria, viruses or toxins is eaten, the symptoms of foodborne illness do not occur right away. If the food poisoning is caused by toxins, the incubation period (the time between eating the food and getting sick) may be just a few hours.

If the food poisoning is caused by bacteria or viruses, however, it usually takes 12 to 48 hours for symptoms to develop. In some cases, it takes three or more days. This means that several meals may be eaten after the meal that caused you to become ill. We tend to blame food poisoning on the last meal but remember, it may have been caused by a meal you ate days before!

Why does food-borne illness occur?

Foodborne illness usually occurs when food is handled so germs can grow and survive in it. These may include:

-Contamination of food by germs from unwashed hands, unclean equipment or work surfaces already contaminated by raw foods.
-Growth of germs in food kept at temperatures favorable for growth 4°C (40°F) to 60°C (140°F) the “danger zone." Anything colder or hotter does not allow germs to grow.
-Bacteria in food due to inadequate cooking or processing.

How does foodborne illness occur in the real world?

These cases describe some foodborne illness outbreaks and what went wrong.

A restaurant employee came to work while ill with diarrhea and did not wash her hands properly after going to the toilet. Salmonella bacteria on her hands likely contaminated the foods that she handled. Thirty-five people who ate at the restaurant became ill with Salmonella food poisoning. Nine were so ill that they were admitted to hospital.

While the food for a wedding banquet was being prepared, the two-year-old daughter of one of the cooks was sampling some food with her bare hands. The prepared food was delivered to the hall, and because of the insufficient refrigerator space, some was left on the counter for several hours. After the ceremony, the wedding guests went to the hall for the wedding banquet. Within four hours of the meal, many guests experienced severe nausea and vomiting. Some even passed out! Analysis of the food revealed that it contained large amounts of Staphylococcus aureus toxin, which causes an illness called staph intoxication. Further tests revealed that the cook’s child had the same strain of Staphylococcus aureus in her mouth as was found in the food. This outbreak was likely a result of both contamination of the food by the hands of the cook’s daughter, and later storage of the food within the temperature danger zone for several hours. The bacteria grew and toxins were produced.

In 1993, 583 people in the U.S. became ill with 'hamburger disease' after eating at the same restaurant. Four people died because of their illness. The likely cause of the outbreak was the undercooking of hamburger patties served by the restaurant.

How is food-borne illness prevented?

Your local Public Health Inspector and other food inspectors are hard at work ensuring that the groceries you buy at the store and the meals you eat at your favorite restaurants are safe and wholesome. At home, however, you must assume the role of inspector. By following the rules for safe food handling listed below, you can prevent food-borne illness from becoming the uninvited guest at your dinner table.

To prevent growth of bacteria in food, keep perishable foods (foods that can spoil) outside the temperature danger zone (4°C to 60°C):
- Keep hot foods hot (above 60°C) and cold foods cold (below 4°C).
- Keep your refrigerator colder than 4°C (you might want to place a thermometer in the fridge, just to make sure).
- Place leftovers in the refrigerator or in the freezer immediately after the meal. Store the leftovers in small containers so that they cool off faster.
- Throw away perishable foods left at room temperature for more than two hours.
- Prepare foods as soon as possible before the meal so that foods do not have to be held at room temperature for long periods.
To prevent contamination of foods:
- WASH YOUR HANDS before handling food, after handling raw meats or poultry, after using the toilet, after changing a diaper often.
- Clean food equipment such as cutting boards, knives, containers and work surfaces well with hot soapy water after the equipment has been in contact with raw meat or poultry. For added safety, wipe equipment with a bleach solution (1 tablespoon bleach per gallon water) after cleaning.
- Store raw meats below ready to eat foods in the refrigerator to prevent contamination by drippings.
- Use only a freshly laundered dish cloth for kitchen clean-up.
To prevent survival of bacteria in foods:
- Thoroughly cook all meat and poultry before serving.
- Never serve hamburgers rare. Cook hamburger patties until the meat is brown (not pink) in the centre and the juices are brown (not red or pink).

How do I know a restaurant is safe?

Although Public Health Inspectors work with restaurant operators to maintain safety, they cannot be everywhere. If you eat out, you should be alert to ensure that restaurant staff are following the above procedures. Watch for:

unclean conditions (dirty floors/walls) in the dining room
food that is not properly cooked, such as underdone hamburger or poultry)
perishable food stored at room temperature
poor hygiene of the staff serving or preparing food
evidence of insects, rodents or other pests
dirty cutlery or dishes

If you notice any of these things, discuss your concerns with the restaurant management. If they are not dealt with to your satisfaction, consider dining elsewhere and calling your health department.

What should I do if someone in my family has a food-borne illness?

If you suspect that you or someone in your household has a food-borne illness:

Visit your doctor, especially if the symptoms are severe. A stool sample should be taken to determine if a food poisoning bacteria is the reason for the illness.
Contact your local health department.

You will likely be asked where and what you have eaten in the several days prior to your illness. The more detailed information you provide, the higher the chance that a health inspector can pinpoint the food that caused your illness.

More questions about foodborne illness? Contact your local Public Health Inspector.

Food Poisoning Was it something I ate?

Food-borne illness (food poisoning) strikes about two million Canadians and costs society over $1 billion each year. Accurate numbers are difficult to determine because only about one in 25 cases is reported.