Food born illnesses
Exposure to food contaminants of chemical, physical, and biological origin can cause adverse health effects in humans.
The physical and biological contaminations can lead to exposure to microorganisms such as bacterial, viral, and other parasites that can either cause adverse health effects directly or produce toxins that lead to food poisoning. In general, foodborne illnesses are caused by bacteria, viruses, parasites, and toxins from bacteria and molds. The difference between foodborne illnesses and food poisoning is that foodborne illnesses describe all illnesses from contaminated food or beverage, while food poisoning is an illness caused specifically, by toxin produced from bacteria or mold.
Contamination can occur in the food systems from growing, harvesting or catching, processing, storing, shipping, or preparing. Food can be contaminated at any time from food production (farm or fishery) to table.
Exposure to harmful contaminants can be through poor hand washing practices especially after visiting the toilet or helping a child in the toilet. The contaminants can either reach the stomach directly from the unwashed hand or be transmitted to the food during food preparation and food serving. Other sources of food contamination can be not cleaning and disinfecting food preparation areas and utensils used for food preparation and serving. Last but not least cause of food contamination is improper storage practices.
Disease cause |
Timing of symptoms |
Common sources |
| Bacillus cereus (bacterium) | 30 minutes to 15 hours. | Foods such as rice, leftovers, sauces, soups, meats and others that have sat out at room temperature too long. |
| Campylobacter (bacterium) | 2 to 5 days. | Raw or undercooked poultry, shellfish, unpasteurized milk, and contaminated water. |
| Clostridium botulinum (bacterium) | 18 to 36 hours. Infants: 3 to 30 days. | For infants, honey. Home-preserved foods including canned foods, fermented fish, fermented beans and alcohol. Commercial canned foods and oils infused with herbs. |
| Clostridium perfringens (bacterium) | 6 to 24 hours. | Meats, poultry, stews and gravies. Commonly, food that is not kept hot enough when served to a large group. Food left out at room temperature too long. |
| Escherichia coli, commonly called E. coli (bacterium) | Usually, 3 to 4 days. Possibly, 1 to 10 days. | Raw or undercooked meat, unpasteurized milk or juice, soft cheeses from unpasteurized milk, and fresh fruits and vegetables. Contaminated water. Feces of people with E. coli. |
| Giardia lamblia (parasite) | 1 to 2 weeks. | Food and water contaminated with feces that carry the parasite. Food handlers who are carriers of the parasite. |
| Hepatitis A (virus) | 15 to 50 days. | Raw and undercooked shellfish, fresh fruits and vegetables, and other uncooked food. Food and water contaminated with human feces. Food handlers who have hepatitis A. |
| Listeria (bacterium) | 9 to 48 hours for digestive disease. 1 to 4 weeks for body-wide disease. | Hot dogs, luncheon meats, unpasteurized milk, soft cheeses from unpasteurized milk, refrigerated smoked fish, refrigerated pates or meat spreads, and fresh fruits and vegetables. |
| Norovirus (virus) | 12 to 48 hours. | Shellfish and fresh fruits and vegetables. Ready-to-eat foods, such as salads and sandwiches, touched by food handlers with the virus. Food or water contaminated with vomit or feces of a person with the virus. |
| Rotavirus (virus) | 18 to 36 hours. | Food, water or objects, such as faucet handles or utensils, contaminated with the virus. |
| Salmonella (bacterium) | 6 hours to 6 days. | Most often poultry, eggs and dairy products. Other foods such as fresh fruits and vegetables, meat, poultry, nuts, nut products, and spices. |
| Shellfish poisoning (toxin) | Usually 30 to 60 minutes, up to 24 hours. | Shellfish, including cooked shellfish, from coastal seawater contaminated with toxins. |
| Shigella (bacterium) | Usually, 1 to 2 days. Up to 7 days. | Contact with a person who is sick. Food or water contaminated with human feces. Often ready-to-eat food handled by a food worker with shigella. |
| Staphylococcus aureus (bacterium) | 30 minutes to 8 hours. | Meat, egg salad, potato salad or cream-filled pastries that have been left out too long or not refrigerated. Foods handled by a person with the bacteria, which is often found on skin. |
| Vibrio (bacterium) | 2 to 48 hours. | Raw or undercooked fish or shellfish, especially oysters. Water contaminated with sewage. Rice, millet, fresh fruits and vegetables. |
Safe temperatures for storage and preparation of food are 60 C and above for cooked food, storage up to 4 days at temperature below 4 C and freeze storage at temperature -18 and below