A Complex Mystery: Finding the Sources of Foodborne Disease Outbreaks
I work in a group at CDC that investigates foodborne illnesses in the United States — illnesses like salmonellosis and E. coli infection. One challenge we face during an outbreak investigation is trying to figure out the source of the outbreak.
When a group of people consume the same contaminated food, an outbreak of illness can occur. This group may be people who ate a meal together or people who happened to buy and eat the same contaminated item from a grocery store or at a restaurant.
Here’s why outbreaks can be such a mystery:
- When people get sick from food, they often assume the cause was the last thing they ate before they started feeling ill. That’s often not the case. For many foodborne illnesses, it can take anywhere from several hours to several days before people start to feel sick. The cause could have been something they ate several days ago, something they might not even remember eating.
- The contaminated food usually looked, smelled, and tasted perfectly fine, making it sometimes very difficult to determine exactly what made them sick.
- If safe food production and handling practices were not followed, the food could have become contaminated at any point, from the time the food was harvested or produced until it was eaten.
- People who get sick with a foodborne illness don’t always see a health care provider. When they do, the providers don’t always test for bacteria that cause foodborne illness. These test results are very important, because CDC and other groups need the results to detect outbreaks.
- Because people are often not interviewed until weeks after they became sick, they may have trouble remembering what foods they had eaten or what spices and condiments they may have added to their food.
So, how do we figure out which foods are making people sick? Some of the things we do are:
- Use technologies, such as “DNA fingerprinting” of bacteria from ill people to help determine which ones might be linked to a common source of infection.
- Interview people who have gotten sick to find out what foods they recently ate.
- Interview people who haven’t gotten sick to compare what foods they recently ate to the sick people.
- Study information from previous outbreaks to see which foods have often been a source before.
- Compare the types of bacteria found in food or ingredients during the outbreak to the types found in people who are sick.
How does this affect you? One thing to remember is that only a tiny fraction of foodborne illnesses are reported as part of an outbreak. While it’s important to keep track of food recalls to avoid getting sick, it’s equally important to follow the basic food handling rules: Clean, Cook, Separate, and Chill. And, if you suspect that you have a foodborne illness, report it to your local health department. Often calls from concerned citizens like you are how outbreaks are first detected.
Questions and Answers
Posted April 14, 2010
Q. How about expiration dates for food in schools and hospitals?
A. The information we provide is intended for use by consumers in the home. For information about storage times of food in a food service environment, like a school or hospital, please contact your local or state health department. For information about food safety and the elderly, see Food Safety for Older Adults.
For consumer information on expiration dates and product dating for foods in the home, see Food Product Dating. The two charts under Storage Times at the bottom of the page provide details on refrigerator home storage of fresh and uncooked food products as well as processed products.
Q. Are there easy ways to determine whether an illness is caused by food poisoning when other types of illnesses have similar symptoms?
A. Unfortunately, many different kinds of illnesses can cause diarrhea, fever, or abdominal cramps, and they can spread in different ways, making it difficult to determine if your illness was caused by a food or by something else. Some common viruses can spread from one person to the next without involving food. Many bacteria and parasites can spread through food, and also water, or from animals or from other infected people.
Determining which bacteria or other germ is the cause of the illness depends on laboratory tests. Even if once you know the germ that caused it, determining that it came from food can take a public health investigation that is not often done. If your illness is severe enough, visit your health care provider. If you are concerned that it really is from food, call your local health department.
What Do You Do If You Have a Recalled Product?
In my role as chief medical officer in the Center for Food Safety and Applied Nutrition, I am responsible for providing oversight for medical issues relating to food safety that may arise, including product recalls. A food recall occurs when a company removes a food product from the market because of the possibility that the food may be contaminated or mislabeled.
You may have seen a number of food recalls in the news lately. The news alerts usually include information to help you identify whether you have the product in your pantry, refrigerator, or freezer. So, what should you do if you find a recalled food in your own home?
Step 1: Don’t panic!
Most food recalls are not associated with a food illness outbreak, and many recalls are issued because there is a potential for the food to be contaminated. Often, food manufacturers issue a recall as a precautionary measure.Step 2: Don’t eat the food.
Even though the food product may be recalled as a precaution, do not eat it! It’s always better to be safe than sorry. And please don’t give the food to other people (do not donate it to a food bank). Don’t feed it to your pets, either, because pets can get food poisoning, too.Step 3: Don’t open the food.
Resist the temptation to open the food and check it. You can’t see, smell, or taste the bacteria or viruses that cause food illnesses. If you do open or handle the product, remember to wash your hands thoroughly with warm water and soap for 20 seconds after handling it.Step 4: Check the recall notice to find out what to do with the food.
When a manufacturer recalls a food product, they provide instructions on what to do with the product. Typically, the instructions will indicate that you need to do one of the following:- Return the product to the store where you bought it for a refund.
- Dispose of the product properly so that other people or animals cannot eat it. (This is particularly important if you opened the product.)
The easiest way to check a recall notice is to go to our Food Recalls and Alerts page. The latest recalls appear in the orange “widget” in the top right corner of the page. If you want to keep up with all new recalls, you can:
- Subscribe to email updates: You’ll get a new email every time a food recall or allergy alert is issued.
- Follow our news feed: The feed contains the same information as the emails, but in a format that you can see in a news reader.
We also send out the major recalls and allergy alerts on our Twitter account, @foodsafetygov.
If you’d like to understand more about food recalls, see the new RecallBasics.org site sponsored by the Partnership for Food Safety Education.
Meat in the Refrigerator: How Long Does It Last?
On behalf of everyone in government who works to keep your food safe, welcome to the FoodSafety.gov blog!
By way of introduction, I’m the manager of the USDA’s Meat and Poultry Hotline. The Hotline is a toll-free telephone service that is available year round, Monday through Friday, to answer your questions about meat, poultry, and egg products. We receive over 80,000 calls a year from people like you who want to know how to prepare and store these foods safely. We also answer questions online at AskKaren.gov.
As you might imagine, there are some questions that we get on a regular basis. In fact, the most frequently asked question that we hear on the Hotline is:
How long can I keep meat in the refrigerator?
What would we do without our refrigerators! When it comes to appliances that keep our foods safe, the refrigerator may be the most important because it slows down the growth of bacteria that cause food poisoning. At temperatures between 40 and 140 °F, bacteria grows most rapidly. That’s why we call this temperature range “the Danger Zone.”
A refrigerator set to 40 °F or below will protect most foods – but not forever. The cool temperatures slow down bacterial growth but they don’t stop the growth completely. So, it’s important to use food in a timely fashion to help maintain freshness and quality. Over time, even chilled foods will spoil.
Here are some basic guidelines for storing meat in the refrigerator.
- Raw ground meats, all poultry, seafood, and variety meats: Refrigerate 1 to 2 days.
- Raw roasts, steaks, and chops (beef, veal, lamb, and pork): Refrigerate 3 to 5 days.
- Cooked meat, poultry, and seafood: Store in the refrigerator 3 to 4 days.
Because we get so many questions about storing food safely in the refrigerator, we put together this chart, which lists storage times for all sorts of meats and meat products:
Storage Times for the Refrigerator and Freezer
It’s a great resource, and we recommend that you bookmark this page or print it out for future reference.
If you’re looking for more details on refrigeration, from the history of refrigeration to removing odors from refrigerators, check out Refrigeration and Food Safety on USDA’s Food Safety and Inspection Service Web site.
We look forward to answering your questions and helping you keep food safe. If you have questions or comments about this topic, add a comment here and let us know. And don’t forget that you can always reach the Hotline at 1-888-674-6854 toll-free or online at AskKaren.gov.
Questions and Answers
Posted April 1, 2010
Q. Are retailers supposed follow the guidelines in this blog? What happens if they don't?
A. The guidelines that we provide on FoodSafety.gov are intended for individuals who buy and prepare food for themselves and their families. When it comes to retail stores, restaurants, and other businesses that deal with food, the government is responsible for setting standards, conducting inspections, and enforcing the law when businesses don't comply with the standards. If you'd like more information, take a look at the Inspections & Compliance section of our site.
Q. How does the use of a home vacuum sealer change the time frames in this blog?
A. Our storage guidelines are the same for home vacuum packaged meats and poultry.
Q. The Danger Zone recommended by ServSafe is different from the one you specified here. Why?
A. The ServSafe recommendations are based on the FDA Food Code, which is intended for retail and food service establishments, such as grocery stores, restaurants, and other institutions that serve food. Those guidelines are for trained cooks in these businesses who are using professional cooking equipment. By contrast, our recommendations on FoodSafety.gov are intended for home cooks.
Q. If poultry can be in the refrigerator one day, how do you thaw out a turkey when the label says to leave it in the refrigerator 2-3 days?
A. Once the turkey is fully thawed, it is like a fresh turkey and it can be refrigerated 1-2 additional days. Take a look at our Turkey Thawing Chart to see how long it takes to thaw a turkey in the refrigerator or in cold water.