Bulletin #2258, Food Safety Facts: Salmonella and Food Safety: Questions and Answers
By Mahmoud El-Begearmi, Extension Professor, Nutrition, and Food Safety
Updated and reviewed by Jason Bolton and Al Bushway, University of Maine Cooperative Extension and Department of Food Science and Human Nutrition
Table of Contents:
- What Is Salmonella?
- What Is Salmonellosis?
- How Do Salmonella Bacteria on Food Make People Sick?
- What Are the Symptoms of Salmonellosis?
- Are There Long-Term Consequences to Salmonellosis?
- How Many People Get Sick from Salmonellosis?
- What Foods Are Most Likely to Make People Sick?
- Are Kosher or “Free-Range” Chickens Lower in Salmonella Bacteria?
- What Is the USDA Doing to Prevent Salmonella Contamination?
- How Can Salmonellosis Be Prevented?
- Table: USDA temperature guidelines for properly cooked meat
Salmonella is the most frequently reported cause of foodborne illness. According to the Centers for Disease Control (CDC) there are approximately 40,000 cases of Salmonellosis reported each year in the US. Much is being learned about Salmonella and the risks associated with it through FoodNet, the Foodborne Diseases Active Surveillance Network. Begun in 1995, FoodNet is a collaborative project of the U.S. Department of Agriculture’s (USDA) Food Safety and Inspection Service (FSIS), CDC, the Food and Drug Administration (FDA), and seven participating states. FoodNet tracks cases of foodborne illness to better gauge the prevalence of food-related illness in this country and to monitor the effectiveness of food safety programs in reducing foodborne illness.
It is important to remember that many food products may contain bacteria. A comprehensive farm-to-table approach to food safety is necessary. Farmers, industry, food inspectors, retailers, food service workers, and consumers are each critical links in the food safety chain. This fact sheet answers common questions about Salmonella, describes how USDA is addressing the problems of Salmonella contamination and offers guidelines for safe food handling to prevent bacteria, such as Salmonella, from causing illness. Researchers in the area of food science are also gaining invaluable information and a better understanding of antibiotic-resistant Salmonella through applied research.
This single celled organism is too small to be seen without a microscope and is termed a bacterium. Salmonella bacteria live in the intestinal tract of animals and human hosts. Salmonella are usually transmitted to humans by eating foods contaminated with animal feces. The Salmonella family includes over 2,300 serotypes of bacteria. Two types, Salmonella Enteritidis and Salmonella Typhimurium, account for approximately half of all human infections. Strains that cause no symptoms in animals can make people sick, and vice versa. If present in food, the bacteria do not affect the taste, smell or appearance of the food. Contaminated foods usually look and smell normal.
Salmonellosis, or a Salmonella infection, is the illness that can occur if live Salmonella bacteria enter the body, usually through eating foods containing the bacteria. FDA estimates about 2 to 4 million cases of foodborne illness and 400 deaths are a result of Salmonellosis. Salmonellosis is one of the most common bacterial foodborne illnesses, but many cases could be prevented by proper food handling practices.
Bacteria can grow on just about any food, such as meat, poultry, seafood, eggs, and dairy products, as well as vegetables and fruits, such as beans, grains, orange juice, cantaloupe, and sprouts. To survive and multiply, bacteria need time and the right conditions: food, moisture, and warm temperatures. The ideal temperature for bacterial growth is between 40 and 140 degrees F. This is also known as the “danger zone” and you should limit your food’s exposure to this temperature range.
Salmonella present on raw chicken or meat can survive if they are not cooked thoroughly. Salmonella can also cause foodborne illness through cross-contamination. For example, juices from raw meat or poultry prepared on a cutting board could contaminate salad ingredients if the board was not washed and sanitized before cutting up the salad ingredients. If the contaminated salad sat at room temperature for any length of time, the Salmonella would multiply to dangerous numbers. The person who eats the salad then also eats the bacteria and becomes ill.
According to CDC, most people experience diarrhea, abdominal cramps, and fever within 8 to 72 hours after eating contaminated food. Additional symptoms may be chills, headache, nausea, and vomiting. Symptoms may last 4-7 days. Many people ill with salmonellosis recover without treatment and may never see a doctor. If the Salmonella spreads to the bloodstream, then antibiotics are a mandatory treatment. However, Salmonella infections can be life-threatening, especially for the very young, the elderly, and for persons with impaired immune systems.
Persons with diarrhea usually recover completely, although it may be several months before their bowel habits are entirely normal. A small number of persons who are infected with Salmonella will develop pains in their joints, irritation of the eyes and painful urination. This is called Reiter’s syndrome. It can last for months or years and can lead to chronic arthritis that is difficult to treat.
Not all cases of foodborne illness are reported, but experts believe that anywhere from 2 to 4 million people contract salmonellosis each year. The only way to confirm salmonellosis is to conduct laboratory tests on the stools of the ill person, a process that takes several days. To overcome the difficulties caused by unreported cases, the collaborating FoodNet sites have set up a system to actively identify laboratory-confirmed cases of foodborne illnesses. This system will provide more specific numbers in the future.
Any raw food of animal origin, such as meat, poultry, milk and dairy products, eggs, seafood, and some fruits and vegetables, may carry Salmonella bacteria. The bacteria can survive to cause illness if these foods are not thoroughly cooked. This means that making sure meats are cooked to an appropriate internal temperature is vital when preventing salmonellosis. The bacteria can also cause illness if they contaminate any other food that comes in contact with the raw food. Safe food handling practices are necessary to prevent bacteria on raw food from causing illness.
FSIS does not know of any valid scientific information that shows that any specific type of chicken has more or less Salmonella bacteria than other poultry.
Under USDA’s new science-based inspection system, FSIS will test meat and poultry samples to identify pathogens, including Salmonella. For the first time ever, FSIS is requiring all processing plants to reduce bacteria by means of a Hazard Analysis and Critical Control Point (HACCP) plan and accompanying testing and performance standards. These national performance standards will be adjusted downward over time, even further reducing bacteria levels.
Bacteria on raw foods of animal origin do not have to cause illness. The key to preventing illness, at home, in a restaurant, at a church picnic or anywhere, is to prevent the bacteria from growing to high levels and to destroy the bacteria through thorough cooking. Follow these guidelines for safe food preparation:
Wash Hands and Surfaces Often
- Wash your hands with hot soapy water before handling food and after using the bathroom, changing diapers and handling pets.
- Wash your cutting boards, dishes, utensils and counter tops with hot, soapy water after preparing each food item and before you go on to the next food. Sanitize with a chlorine and water solution. 1 tablespoon of full strength bleach (6% sodium hypochlorite) to 1 gallon of water.
- Use plastic or other non-porous cutting boards. These boards should be run through the dishwasher—or washed in hot, soapy water—after use.
- Consider using paper towels to clean up kitchen surfaces. If you use cloth towels, wash them often in the hot cycle of your washing machine.
- Separate raw meat, poultry, and seafood from other foods in your grocery shopping cart and in your refrigerator. It is a good idea to place meat in a secondary plastic bag to prevent cross-contamination.
- Use a different cutting board for raw meat products.
- Always wash hands, cutting boards, dishes, and utensils with hot, soapy water after they come in contact with raw meat, poultry, and seafood.
- Never place cooked food on a plate that held raw meat, poultry, and seafood.
- To prevent cross-contamination when working with eggs, they should be treated as raw meat. Salmonella can be found in and on eggs so it is imperative to clean and sanitize all surfaces, equipment, and utensils that come in contact with raw eggs.
Cook to Proper Temperatures
- Use a clean thermometer, which measures the internal temperature of cooked foods, to make sure meat, poultry, casseroles, and other foods are cooked all the way through. Wash thermometer with hot and soapy water between uses.
- Cook all meats to the appropriate internal temperatures found in the table below.
| Safe internal
|Beef, veal, and lamb steaks and roasts
|Ground meat (beef, veal, pork, sausages, and lamb)
|Chicken, turkey, duck (whole, pieces, and ground)
- Fish should be opaque (not clear) and flake easily with a fork.
- When cooking in a microwave oven, make sure there are no cold spots in food where bacteria can survive. For best results, cover food, stir and rotate for even cooking. If there is no turntable, rotate the dish by hand once or twice during cooking.
- Bring sauces, soups, and gravy to a boil when reheating. Heat other leftovers thoroughly to at least 165 degrees F (steaming hot).
- Refrigerate or freeze perishables, prepared foods and leftovers within two hours or sooner. One hour for days of 90°F or warmer.
- Never defrost food at room temperature. Thaw food in the refrigerator, under cold running water or in the microwave. Marinate foods in the refrigerator.
- Divide large amounts of leftovers into small, shallow containers for quick cooling in the refrigerator.
- Don’t pack the refrigerator. Cool air must circulate to keep food safe
For more information about food safety, call USDA’s Meat and Poultry Hotline at 1-800-535-4555 or contact your University of Maine Cooperative Extension county office.
This publication was revised and reprinted from “Salmonella Questions and Answers,” a backgrounder publication produced by the FSIS, USDA in February 1998.
Information in this publication is provided purely for educational purposes. No responsibility is assumed for any problems associated with the use of products or services mentioned. No endorsement of products or companies is intended, nor is criticism of unnamed products or companies implied.
© 1991, 2011
Call 800.287.0274 (in Maine), or 207.581.3188, for information on publications and program offerings from University of Maine Cooperative Extension, or visit extension.umaine.edu.
The University of Maine is an EEO/AA employer, and does not discriminate on the grounds of race, color, religion, sex, sexual orientation, transgender status, gender expression, national origin, citizenship status, age, disability, genetic information or veteran’s status in employment, education, and all other programs and activities. The following person has been designated to handle inquiries regarding non-discrimination policies: Sarah E. Harebo, Director of Equal Opportunity, 101 North Stevens Hall, University of Maine, Orono, ME 04469-5754, 207.581.1226, TTY 711 (Maine Relay System).