Introduction

Foodborne illnesses result from eating food contaminated with bacteria, the poisons bacteria produce, viruses, parasites, or chemicals in the food.

Symptoms may include diarrhoea, vomiting, fever, malaise, headache, nausea and dizziness. Reactions vary according to the individual and the organism responsible for the illness.

The symptoms of a foodborne illness may be mild and last only a few hours, or they may be serious, lasting much longer and requiring intensive medical treatment. In specific groups such as children and the elderly, death may occur.

In Alberta, more than 3000 cases of foodborne illnesses are reported each year. This booklet provides basic information on these illnesses and their causes.

Further information can be obtained from your local health unit.

Bacterial

• Campylobacter Enteritis
• Clostridium Perfringens Food Poisoning
• Haemorraghic Colitis
• Listeriosis
• Salmonellosis
• Shigellosis
• Staphylococcal Food Poisoning

Parasitic

• Amoebiasis
• Giardiasis

Viral

• Hepatitis A

Bacterial Foodborne Diseases

All food, unless just cooked or sterilized, contains some bacteria. The number present will depend on the manner in which the food has been handled and stored. If allowed to grow, some of these bacteria may cause spoilage. Generally, these spoilage bacteria are harmless and do not cause illness. However, if spoilage is noticeable, the food should not be consumed.

Harmful bacteria often do not alter the appearance, taste or smell of food. Because of this, it is impossible to visually determine whether or not food is contaminated. Only a laboratory analysis can verify the presence of these bacteria.

How do bacteria cause foodborne illnesses?

Foodborne illness occurs if:

• The bacteria in or on food have survived the cooking, processing and/or storage steps taken before the food was eaten.
• The bacteria in or on food have multiplied to reach sufficient numbers, or produce toxins in sufficient quantities to cause disease. This sometimes occurs before the food is eaten (i.e. due to poor storage and handling conditions,) and sometimes occurs in the body of the person eating that food.
• Bacteria have been brought into the preparation area either by raw, unwashed food, dirty hands or unsanitary equipment, and these have contaminated prepared foods, or foods being prepared.

After consuming bacteria or a toxin, there is usually an incubation period before illness occurs. It is during this time that the bacteria multiply and/or the toxin reaction occurs. The incubation time, and the duration of the illness, depends on the type of bacteria or toxin consumed.

Campylobacter Enteritis

Campylobacter enteritis is an illness caused by a bacteria from the Campylobacter group. Campylobacter infections usually occur three to five days after ingestion of the organism and generally results in diarrhoea, abdominal pain, fever, nausea and vomiting.

Campylobacter enteritis occurs throughout the world, particularly in the temperate areas during the warmer months. The bacteria may be responsible for some "traveller's diarrhoea".  Campylobacter enteritis is self limiting and of short duration, with the symptoms lasting from one to four days.

How is Campylobacter Enteritis spread?

Campylobacter bacteria may be found in the faeces of domestic and wild animals, particularly poultry, dogs, cats and pigs. These can also be found in cattle which appear not to be affected by the organism. Illness may occur after individuals ingest food, water or especially unpasteurized milk contaminated with the organisms. Cross­contamination and cross infections are also possible methods of transmission. As a result, good personal hygiene and sanitation must be practised, especially when handling infected infants.

How can you prevent Campylobacter Enteritis?

• Drink pasteurized milk only.
• Thoroughly cook all foods derived from animal sources particularly poultry.
• Cook poultry to an internal temperature of  74 degrees Celsius. The use of a thermometer ensures that the proper temperature is reached.
• Avoid recontamination of cooked foods by placing them on clean surfaces which were not previously used for preparation of other foods.

How can you control Campylobacter Enteritis?

See your personal physician for treatment.
If you have been infected, be prepared to answer detailed questions and to submit faecal samples to health authorities.
Infected individuals should be particularly careful about personal hygiene and should thoroughly wash their hands before handling or preparing foods.
Surface water used for human consumption requires filtration and disinfection.

Clostridium Perfringens Food Poisoning

Clostridium Perfringens food poisoning is a type of food poisoning caused by the bacterium Clostridium perfringens and characterized by a sudden onset of abdominal pain and diarrhoea. Nausea is common but vomiting and fever are usually absent. This type of food poisoning is mild and usually lasts only one day or less.

How is Clostridium Perfringens food poisoning spread?

Clostridium Perfringens is found in soil as well as in the intestines of humans and animals. Illness occurs when individuals eat food contaminated with faeces or soil.
Foods commonly involved include meats that have been contaminated and then improperly refrigerated, improperly cooked, or inadequately reheated (i.e. stews, meat pies and gravies made from beef, turkey or chicken).

How do you prevent Clostridium Perfringens food poisoning?

• Serve meat dishes hot or refrigerate them until serving time.
• Reheat precooked meat dishes rapidly to a temperature of 60 degrees Celsius or higher.
• Do not partially cook meat and poultry one day and reheat the next.
• Divide stews and similar dishes prepared in bulk into several shallow containers for more rapid cooling in the refrigerator.
• Educate food handlers on the risk involved with large scale cooking, especially of meat dishes.
• Wash hands well with soap and water immediately after using the toilet and always before handling or eating food.

How do you control Clostridium Perfringens food poisoning?

• See your personal physician for treatment.
• If a food poisoning outbreak is suspected in your community, an in­depth investigation will be conducted. If you have been infected you should be prepared to answer detailed questions, and to submit faecal samples to health authorities.
• Infected individuals should be particularly careful about personal hygiene and should thoroughly wash their hands before handling or preparing food.
   

Haemorraghic Colitis (E. Coli 0157:H7)

Haemorraghic colitis, commonly referred to as hamburger disease or Barbecue Season syndrome, is a newly recognized type of foodborne illness which is caused by a certain strain of the common bacterium Escherichia coli (i.e. 0157:H7). These bacteria produce a poison or toxin which damages the lining of the intestine producing diarrhoea and pain. While most people recover from this disease within two weeks, in a very small number of cases, the toxin results in a serious complication called HAEMOLYTIC URAEMIC SYNDROME (or HUS). This illness affects the kidneys and blood and is especially dangerous to young children and the elderly. Death can result from either HUS or the intestinal disease.

Haemorraghic colitis is characterized by severe stomach cramps, dehydration and bloody diarrhoea two to eight days after eating contaminated food. A mild fever may be present and the illness usually lasts seven to ten days.

How Is Haemorraghic colitis spread?
Although E. coli0157:H7 has been found in pork, beef and poultry products, haemorraghic colitis is frequently linked with undercooked meat and occasionally with unpasteurized milk. Person to person spread also occurs.

How do you prevent Haemorraghic Colitis?

• Since the organism is destroyed by cooking, ensure all meats are thoroughly cooked to at least 71 degrees Celsius. For larger cuts, a meat thermometer should be used to check the internal temperature.
• Serve cooked meats immediately or keep them hot (60 degress Celsius). Don't let meats sit at room temperature.
• Refrigerate leftover meats as soon as possible after the meal. Reheat all leftovers to 74 degress Celsius.
• Refrigerate or freeze meats as soon as possible after buying.
• Thaw frozen meats in the refrigerator, not at room temperature.
• Wash hands thoroughly before preparing food, after handling raw meats, and after toilet use.
• Prepare raw hamburger patties or other meats quickly, and either cook them right away, or put them in the refrigerator. Don't let raw meats sit at room temperature.
• Wash all utensils, cutting boards and counters with hot soapy water to prevent bacteria from raw meats contacting other foods.
• Place cooked meats on clean plates; Don't re­use utensils, plates or platters that have been in contact with raw meat.
• Avoid unpasteurized milk.
• Never order or accept undercooked ground meat products in an eating establishment.

How do you control Haemorraghic Colitis?

• See your personal physician for treatment.
• Consider taking a food sanitation and hygiene course from your local health unit.
• The Alberta Public Health Act requires that physicians and laboratories notify the local health unit when a case or an outbreak of haemorraghic colitis has been identified. An in­depth investigation will be conducted. If you have been infected, you should be prepared to answer detailed questions, and to submit fecal samples to health authorities.
• Infected individuals should be particularly careful about personal hygiene and should thoroughly wash their hands before handling or preparing food.

Listeriosis

Listeriosis is an illness caused by the Listeria bacterium found in soil and water. Animals such as cattle and sheep can carry it without appearing ill and can contaminate foods of animal origin such as meats and dairy products. About 10 per cent of healthy persons may also harmlessly carry this organism in their bowel. It can be found in a variety of raw foods, such as uncooked meats and vegetables, as well as in processed foods that become contaminated after processing, such as soft cheeses and cold cuts at the deli counter. Vegetables can become contaminated from the soil or from manure used as fertilizer. Unpasteurized (raw) milk or foods made from unpasteurized milk may contain Listeria. About seven cases are reported in Alberta each year.

Symptoms can be similar to the flu, with fever, muscle aches, and often gastrointestinal symptoms such as nausea or diarrhea. Listeriosis can be deadly if it causes meningitis, an infection of the fluid around the brain, causing headache, stiff neck, confusion, loss of balance, or seizures.

Who is at risk? 

Pregnant women are about 20 times more likely than other healthy adults to get listeriosis. One-third of listeriosis cases happen during pregnancy. Infected pregnant women may experience only a mild, flu-like illness; but infection during pregnancy can lead to premature delivery, illness in the newborn, or stillbirth. Persons with weakened immune systems, including those with cancer, diabetes, kidney disease, AIDS, and those taking glucocorticosteroid (steroid) medications have a higher risk of getting listeriosis. Elderly persons also are at higher risk.

How is listeriosis prevented and how can I protect myself?

Listeria is killed by pasteurization and by heating procedures used to prepare processed meats. Food processing and manufacturing practices reduce the risk of contamination. Precautions include

• Cook raw meat and poultry thoroughly
• Wash raw vegetables thoroughly
• Avoid raw (unpasteurized) milk, cheese or other foods made from raw milk
• Keep uncooked meats separate from vegetables, cooked and ready-to-eat foods
• Separate utensils for raw and cooked foods
• Wash hands, knives, and cutting boards after handling uncooked foods.

If you are pregnant or have a weakened immune system:

• Avoid soft cheeses such as feta, Brie, Camembert, blue-veined, and Mexican-style cheese and refrigerated pates. (There is no need to avoid hard cheeses, processed cheeses, cream cheese, cottage cheese, or yogurt.)
• Avoid refrigerated smoked fish products unless they are cooked.
• Thoroughly cook ready-to-eat foods, such as hot dogs, until steaming hot.
• Although the risk of listeriosis associated with foods from deli counters is low, pregnant women and immunosuppressed persons may choose to avoid these foods or thoroughly reheat cold cuts before eating.

Can Listeriosis be treated?

Listeriosis can be treated with antibiotics. When infection occurs during pregnancy, antibiotics given promptly to the pregnant woman can often prevent infection of the fetus or newborn. Babies with listeriosis receive the same antibiotics as adults, although a combination of antibiotics is often used until physicians are certain of the diagnosis. Even with prompt treatment, some infections result in death, especially in the elderly and others with serious medical problems.
Adapted from BC Centre for Disease Control information

Salmonellosis
Salmonellosis is a food­borne infection caused by Salmonella bacteria. These bacteria multiply in the small intestine and invade the gut lining. Symptoms such as the sudden onset of abdominal pain, diarrhoea, nausea, fever and vomiting are common. Dehydration, especially among infants, may be severe.

How is Salmonellosis spread?
Salmonella bacteria may be found in the faeces of humans and animals (wild and domestic). Both humans and animals may have the bacteria and still appear healthy. Salmonella is also found in food such as raw eggs and egg products, meat and meat products, and poultry.

Illness may occur after individuals eat food or drink water contaminated with faeces. Salmonella infections are usually traced to inadequately cooked poultry, raw sausages, lightly cooked foods containing eggs or egg products, or to unpasteurized dairy products. Contamination also occurs when food such as meat or poultry is prepared with utensils or on counters not cleaned after being previously used.

Salmonella infections usually occur within 12 to 36 hours after eating contaminated food or water.

How do you prevent Salmonellosis?

• Thoroughly cook all foods derived from animal sources, particularly poultry, egg products and meat dishes.
• Cook meats and poultry to an internal temperature of  74 degrees Celsius. The use of a meat thermometer ensures the proper temperature is reached.
• Cook poultry stuffing separately or, if the bird is cooked with the stuffing in it, make sure that it is cooked until very well done.
• Avoid recontamination of cooked foods by placing them on clean surfaces which were not previously used for preparation of other foods.
• Do not allow raw or cooked foods to sit for long periods at room temperature.
• Avoid the use of raw eggs, as in eggnogs or home­made ice cream, and never use dirty or cracked eggs.
• Use only pasteurized milk and milk products.
• Educate food handlers and persons preparing food in the importance of refrigerating food, washing hands before, during and after food preparation, maintaining a sanitary kitchen and protecting prepared foods against contamination by rodents and insects.
• Recognize and control Salmonella infections among domestic animals and pets. Chicks, ducklings and turtles are particularly dangerous as pets for small children.

How do you control Salmonellosis?

• See your personal physician for treatment.
• If a Salmonellosis outbreak is suspected in your community, an in­depth investigation will be conducted.
• If you have been infected you should be prepared to answer detailed questions, and to submit fecal samples to health authorities.
• Infected individuals should be particularly careful about personal hygiene and should thoroughly wash their hands before handling or preparing food.

Shigellosis

Shigellosis is an illness caused by bacteria from the Shigella group. It is commonly known as "bacillary dysentery". Symptoms such as diarrhoea, fever, nausea, vomiting and cramps are most common. Blood may also be found in the faeces.

Shigellosis occurs throughout the world and is most often associated with children under 10 years. If the disease is not properly treated, it can be fatal.

How is Shigellosis spread?
Direct hand­-to-­mouth transfer of contaminated fecal matter can occur when infected individuals do not wash their hands after using the toilet. Shigellosis can also be spread indirectly when individuals eat food or drink water contaminated with bacteria from human feces.

Illness usually occurs within four days of ingesting the organism. Shigellosis can be spread by infected individuals to other people. Some individuals may be unaware they are transmitting the disease because they do not show signs of having the infection. These people are called "asymptomatic carriers".

How can you prevent Shigellosis?

• Wash your hands well immediately after using the toilet and always before handling or eating food. Children especially must be encouraged to wash their hands thoroughly.
• Wash your hands well after contact with infected individuals or their belongings.
• Ensure proper disposal of sewage.
• Protect public water supplies from fecal contamination.
• Ensure milk and milk products are pasteurized.
• Control flies (i.e. screening of windows and doors).
• Travellers to areas with inadequate sanitary facilities should eat only cooked foods, served hot. Avoid ice, salads and raw vegetables when travelling in these areas. Eat only fruits that have been thoroughly washed and can be peeled.

How can you control Shigellosis?

• See your personal physician for treatment.
• Ensure that family, friends and other close contacts of an infected individual are notified.
• Be prepared to submit faecal samples to health authorities.
• Infected individuals should be particularly careful about personal hygiene and should thoroughly wash their hands before handling or preparing food.

Staphylococcal Food Poisoning

Staphylococcal food poisoning is an illness caused by a toxin or poison released by bacteria from the Staphylococcus group. The toxin, which may contaminate food, is not destroyed by cooking.

Symptoms associated with staphylococcal food poisoning are nausea, cramps, vomiting and diarrhoea. Although the illness may be of short duration (i.e., usually less than two days) it can be severe.

How is Staphylococcal food poisoning spread?
The organism is usually found in humans (i.e. abscesses, infected fingers and eyes, acne and nasal secretions). Illness occurs when individuals eat food contaminated with the toxin produced by the bacteria.

Foods commonly contaminated include pastries, custards, salad dressings, sandwiches, sliced meat and meat products (i.e. ham, bacon and pressed meats). Milk from cows with infected udders, dried milk, cream and butter are foods that have also been associated with staphylococcal food poisoning.

How can you prevent Staphylococcal food poisoning?

• Refrigerate all prepared foods (especially sliced and chopped meats, custards and cream fillings) to avoid multiplication of any bacteria introduced into the food. Refrigerate or dispose of left­over foods immediately.
• Educate food handlers about food preparation, kitchen sanitation, refrigeration and personal hygiene. Persons with skin or eye infections should not prepare food.

How can you control Staphylococcal food poisoning ?

• See your personal physician for treatment.
• If a staphylococcal food poisoning outbreak is suspected in your community, an in­depth investigation will be conducted.
• If you have been infected you should be prepared to answer detailed questions, and to submit swabs of nasal passages and infected sores to health authorities. 

Parasitic Foodborne Diseases
In addition to bacteria and viruses, food may also become contaminated with, and transmit, parasites. Fortunately, this is very rare in Canada even for common parasitic diseases like giardiasis (beaver fever). However, with increasing travel to areas where parasitic infections are more common, there is increasing concern about the potential for foodborne parasitic diseases.

The diseases produced by parasites are varied, and in some countries, they are more important than bacterial foodborne illnesses. Many infected individuals do not show signs of infection (asymptomatic), but the symptoms, when they occur, are similar to those produced by bacteria. Diarrhoea is usually the most common symptom.

As with viruses, parasites need a host in which to multiply and contaminated food and water act only to transport the parasite from one host to the next (vectors). Unlike viruses, the parasites from many animals are also capable of causing disease in people.

How parasites cause foodborne illnesses

It is difficult to pin point the precise mode of transfer of the infective agent to the host. Contamination may occur from hand to food or directly from polluted water. As well, if an animal was infected, the parasite may be present deep in the meat (i.e. Trichinosis, Cystocercosis). People may become infected if they eat under­cooked meat or fish; if they drink untreated water or use it in food preparation; or if uncooked foods (i.e. salads) are contaminated by a foodhandler.

Amoebiasis

Amoebiasis is an intestinal disease caused by the parasite Entamoeba histolytica. The disease is commonly known as "amoebic dysentery" and results when the parasite invades the wall of the large intestine, forming ulcers in the process. Symptoms such as diarrhoea, fever, chills, and mild abdominal discomfort are the most common.

How is Amoebiasis spread?

Amoebiasis can be transmitted by water and food contaminated with faeces. Amoebiasis is usually spread by direct hand­to­mouth transfer of the parasites, but the parasites can also travel from the faeces to the mouth via food that has been contaminated. Community outbreaks usually involve water supplies contaminated with cysts. A cyst is the form that allows the parasite to survive outside the host for a long time.

Illness usually occurs within one to four weeks after ingestion of the parasite. Amoebiasis can be spread by infected individuals to other people for many years if treatment is not sought. Some individuals may be unaware they are transmitting the disease because they do not show signs of having the infection. These people are called "asymptomatic carriers".

How can you prevent Amoebiasis?

• Improve the living environment (i.e. prevent overcrowding).
• Dispose of sewage in a sanitary manner.
• Protect water supplies against sewage contamination.
• Wash your hands well with soap and water immediately after using ,the toilet and always before handling or eating food.
• Wash your hands well after contact with infected individuals or their belongings.
• Control flies (i.e. screening of windows and doors).
• Travellers to areas with inadequate sanitary facilities should eat only cooked foods, served hot. Avoid ice, salads and raw vegetables when travelling in these areas. Eat only fruits that have been thoroughly washed and can be peeled.
• Prepare food using safe water supplies.
• Use adequate cooking and refrigeration temperatures to reduce risk of contamination.

How can you control Amoebiasis?

• See your personal physician for treatment.
• Ensure family, friends and other close contacts of an infected individual are notified.
• Be prepared to submit faecal samples to health authorities.
• Ensure that foodhandlers; attend food sanitation and hygiene courses offered by the local health unit.
• Infected individuals should be particularly careful about personal hygiene and should thoroughly wash their hands before handling or preparing food.
  

Giardiasis
Giardiasis is an intestinal disease caused by the parasite Giardia lamblia. Symptoms such as diarrhoea, abdominal cramps, bloating, fatigue and weight loss may occur.

The disease occurs worldwide although it is more common in areas with poor sanitation. Children appear to be infected more frequently than adults.

How is Giardiasis spread?

Giardia lamblia is found in humans and animals (wild and domestic). Beavers have been identified as a source of the parasite. The parasite produces cysts which are responsible for the spread of the disease. Faeces containing these cysts can contaminate both water (most commonly) and food. Direct hand­to mouth transfer of these cysts can occur when individuals do not wash their hands after using the toilet.

Illness usually occurs within two weeks of exposure. Giardiasis can be spread by infected individuals to other people. Some individuals may be unaware they are transmitting the disease because they do not show signs of having the infection. These people are called "asymptomatic carriers".

How can you prevent Giardiasis?

• Practise good personal hygiene by bathing frequently and washing your hands well immediately after using the toilet and always before handling or eating food. Children especially must be encouraged to wash their hands thoroughly.
• Ensure proper disposal of sewage.
• Protect public water supplies from faecal contamination (human and animal).
• If advised by your health unit, boil all drinking and cooking water.
• Use safe water supplies when preparing food.
• Use adequate cooking and refrigeration temperatures to reduce risk of contamination.
  

How do you control Giardiasis?

• See your personal physician for treatment.
• Ensure family, friends and other close contacts of an infected individual are notified.
• Be prepared to submit faecal samples to health authorities.
• Consider taking a food sanitation and hygiene course from your local Health Unit. 
  
  

Viral Foodborne Diseases

In addition to bacteria, food may also be contaminated with viruses. Unlike bacteria, viruses cannot multiply in food and do not cause spoilage. Viruses do not cause any change in the appearance, taste or smell of food and cannot be detected by ordinary laboratory tests. Once they get into the human body, however, they can multiply and cause disease. Viruses that infect people must come from other people (transmitted by hands and sneezing,) or by foods contaminated by sewage.

How viruses cause foodborne illnesses

Viruses spread by food most commonly cause intestinal illness. Like bacteria, they are spread from the hands of infected humans and from contaminated water to food. For example, the presence of viruses in shellfish, grown in sewage ­polluted water, may be significant in causing foodborne illness if the shellfish are eaten raw or undercooked.

Vomiting and diarrhoea caused by an enteric virus is probably much more common than is usually recognized. Fortunately, most viruses are destroyed by adequate cooking but prevention of foodborne viral infections also requires careful attention to personal hygiene and proper food handling and preparation.

Viral Hepatitis A
Hepatitis A (previously called infectious hepatitis) is caused by the Hepatitis A virus. The onset of this illness is often abrupt with fever, malaise, anorexia and abdominal discomfort being the main symptoms. However, many adults and most children may be infected (and infectious) but have no or very mild symptoms. These symptoms may be followed by jaundice which is the yellowing of the skin and the whites of the eyes. The incubation period (the time from exposure to symptoms) is normally about 4 weeks but can be anywhere from 2 to 7 weeks depending on the dose of the virus eaten.

People with symptoms may be ill for as little as 1 ­ 2 weeks, but most people do not feel fully recovered for quite a few weeks. In some rare cases, people are severely ill for several months and liver failure and death occasionally occur.

Because of good sanitation practices in countries like Canada, exposure to the virus does not usually occur until later in life. Children can be infected but this is less common and they are unlikely to show any symptoms.

How is Hepatitis A spread?

Other people are the only source of the hepatitis virus. The virus is found in faeces in high numbers a week or two before symptoms become obvious. Therefore, it is possible to unknowingly spread the virus to other people through lapses in proper personal hygiene (hand washing). Outbreaks have been associated with contaminated water; food contaminated by infected foodhandlers, including sandwiches and salads which are not cooked or are handled after cooking; and raw or undercooked shellfish which were grown in sewage ­polluted waters.

Disease transmission is also frequent in day care centres, particularly where there are children in diapers. In such cases, it is often older family members of children in day care or staff in the day care who are affected, while the children themselves have no symptoms. Household contacts, and people sharing things with other infected individuals, are also at increased risk of infection.

How do you prevent Hepatitis A?

• Thoroughly cook all seafood (oysters, clams and other shellfish) to a temperature of 85 ­90oC for 4 minutes before eating.
• Avoid recontamination of cooked food by placing them on clean surfaces which were not previously used for the preparation of other foods.
• Educate foodhandlers and other persons preparing food about good sanitation and personal hygiene. In particular, emphasis
  should be on proper handwashing before, during and after food preparation, and the sanitary disposal of feces.
• Foodhandlers who are acutely ill should stay off work for at least one week after symptoms develop.
• Never order or accept raw shellfish in an eating establishment.
• Buy or use shellfish obtained from approved sources only.

How do you control Hepatitis A?

• See your personal physician for diagnosis and treatment.
• If a Hepatitis A outbreak is suspected in your community, an in­depth investigation will be conducted.
• If you have been infected, you should be prepared to answer detailed questions, and to submit faecal or blood samples to health authorities.
• Persons who have been in contact with a case of hepatitis may be protected with immune globulin (IG or gamma globulin.) Your doctor or health unit will advise if IG is appropriate for you.