Salmonella is a type of bacteria normally found in the digestive tracts of animals and birds. Most often, salmonella is transmitted to people when they eat food or drink water that is contaminated with animal feces. Exotic pets such as snakes, turtles, and other reptiles can also be carriers and transmit the bacteria to people. The bacteria is also found in the environment. The foodborne illness caused by salmonella is called salmonellosis.
Salmonellosis is also commonly known as "food poisoning" or the "stomach flu." Salmonellosis can vary in severity from very mild to severe. Not everyone who is infected will have symptoms of salmonellosis, although anyone who is infected can spread the infection to other people.
Common symptoms of salmonellosis include abdominal cramps, diarrhea, fever, and nausea, and you will experience symptoms anywhere from 12 to 72 hours after being exposed to the bacteria. Usually, these symptoms last for 4 to 7 days and do not require treatment. More severe cases can require antibiotic therapy or even hospitalization. Seniors, very young children, women who are pregnant, and people with weakened immune systems are more at risk of getting sick from salmonella, and they are more prone to complications of salmonellosis, such as dehydration or septicemia (where the bacteria is present in the blood).
Rarely, people infected with salmonella may develop a condition known as Reiter's syndrome, which is also known as reactive arthritis. Symptoms include joint pain, eye irritation, and painful urination. These symptoms usually appear 3 to 4 weeks after exposure to the bacteria. 50% of affected people experience a complete resolution of symptoms within 6 months and most people's symptoms will go away within 1 year. In some cases, this condition can progress to chronic arthritis.
The estimated number of reported cases of salmonellosis in Canada each year is between 6,000 and 12,000. Due to the wide range in severity of symptoms and the similarity of symptoms between salmonellosis and other illnesses, people are often unaware that they have been infected with salmonella. For this reason, the actual number of cases of salmonella infection is expected to be much higher than the number of cases reported.
Because many different illnesses can cause the same symptoms as salmonellosis, the only way to know for sure that it is a salmonella infection is to get a lab test of stool samples.
The types of food most often involved in salmonella outbreaks (when there are 2 or more cases of salmonellosis with the same source of infection) are raw or undercooked products from animal sources, such as beef, poultry, eggs, and milk. Fruits and vegetables such as alfalfa and bean sprouts, cantaloupe, and tomatoes have also been associated with salmonella outbreaks.
In addition, there have been cases of salmonellosis associated with unpasteurized fruit juice and cider, and unpasteurized dairy products. However, salmonella contamination is not limited to these food items. Any food can become contaminated with salmonella.
Food contamination can occur at any point in the farming, distribution, and food preparation process. Food can become contaminated through the water that is used to grow and process fresh produce. Soiled equipment can also be a source of bacteria.
An important source of food contamination is failure to follow good food handling practices. This can include habits such as not washing hands after handling raw meat, using the washroom, or coming in contact with an animal carrying the bacteria. Improperly cleaning work areas and utensils involved in food preparation, and eating food that has not been thoroughly washed and cooked can also contribute to the spread of salmonella and increase your chances of infection.
Because there are many possible points at which food contamination can occur, it is often difficult to determine the exact source of an outbreak.
Once food has become contaminated with salmonella, it is very difficult to eliminate the bacteria. Freezing or refrigerating food will not kill salmonella, although it will stop the bacteria from reproducing. Peeling vegetables will not make fruits and vegetables safer to eat either, as the bacteria can spread to the inside of the vegetable.
Further, thoroughly cooking food can kill salmonella, but it does not guarantee that the food is safe to eat if proper food handling processes were not followed (e.g., if cross contamination occurred). Food that has been contaminated can still look, smell, and taste normal. If you know that food has been contaminated, throw it out.
To minimize your chances of getting or spreading infection with salmonella, follow these food safety tips:
- Keep eggs in the coldest part of the fridge (generally near the back). Do not place them in the fridge door, where the temperature will fluctuate most.
- Keep raw meat separate from other foods in your shopping cart while at the store, in the fridge, and during preparation. This will help prevent cross contamination.
- Sanitize utensils and work area after preparing food using a dilute bleach solution. To prepare the sanitizer, add 5 mL (1 tsp) of bleach to 750 mL (3 cups) of water in a clearly labelled spray bottle. Spray utensils and work area and allow them to stand momentarily. Rinse utensils and work area with generous amounts of clean water, then dry with clean towels, or allow to air dry.
- Use a food thermometer to make sure that food has been properly cooked. This is the only way to ensure that food has reached a temperature high enough to kill any bacteria that may be present.
- Wash your hands for at least 20 seconds with soap and warm water before and after handling food, especially raw meat. Also, be sure to wash your hands after using the washroom, touching or playing with animals, and cleaning up after pets.
- Wash all fruits and vegetables before eating. Use a brush to scrub vegetables with firm exteriors (e.g., carrots, oranges, potatoes).
- Defrost food at room temperature. Food should be defrosted either in the microwave, in cold water, or in the refrigerator, and it should be used promptly.
- Eat eggs, meat, or poultry that have not been thoroughly cooked.
- Eat products containing raw eggs (e.g., certain salad dressings, cookie dough, homemade hollandaise sauce). If you're preparing these foods at home, use pasteurized eggs. Bacteria such as salmonella are killed in the pasteurization process.
- Eat unpasteurized dairy products (e.g., cream-filled desserts, dessert toppings, cheeses).
- Prepare food for other people if you have been diagnosed with salmonellosis. If you suspect that you may have a salmonella infection, wear disposable gloves when handling food.