How to Prevent Listeriosis Outbreaks
By Howard Seltzer, National Education Advisor, Center for Food Safety and Applied Nutrition, FDA
The ongoing multistate outbreak of food poisoning associated with cantaloupes has put a bad bug called Listeria monocytogenes in the spotlight.
What is Listeria Monocytogenes?
It's a harmful bacterium that causes a foodborne illness called listeriosis. It's found in the environment – soil, water, decaying vegetation, and the intestinal tract of animals.
What happens when people get Listeriosis?
A person with listeriosis usually has fever and muscle aches. People who think they might have become sick with listeriosis should consult their doctor.
Listeriosis is relatively rare but can be fatal, especially in people at high risk for listeriosis: older adults; young children; people with compromised immune systems, such as cancer, diabetes, or HIV/AIDS patients; and pregnant women. In pregnant women, listeriosis can cause miscarriage, stillbirth, and serious illness or death in newborn babies.
What Causes Listeria in our Food?
If food is processed, packaged, or handled in unsanitary conditions, it can become contaminated with Listeria. This is of particular concern with ready-to-eat, refrigerated foods, such as luncheon meats and pates or meat spreads, because most of these are not reheated before eating – a step that would kill Listeria. In addition, unpasteurized milk and products made with unpasteurized milk can carry Listeria, as well as other dangerous bacteria, such as Salmonella and E. coli.
It’s very important to understand that, unlike most other foodborne bacteria, Listeria can grow at refrigerator temperatures. That means the longer foods contaminated with Listeria are stored in the refrigerator, the more opportunity Listeria have to multiply. What’s more, foods contaminated with Listeria can cross-contaminate surfaces they come into contact with – surfaces in the refrigerator and around the kitchen.
How can I prevent Listeriosis?
Consumers, especially at-risk consumers and those who take care of them, should follow these simple steps to help prevent listeriosis:
- Avoid foods containing unpasteurized milk
- Wash hands with warm water and soap for at least 20 seconds before and after handling food. Clean refrigerators and other food preparation surfaces regularly and effectively. Wash the inside walls and shelves of the refrigerator, cutting boards and countertops; then sanitize them with a solution of one tablespoon of chlorine bleach to one gallon of hot water; and finally dry with a clean cloth or paper towel that has not been previously used.
- Always wash hands with warm water and soap following the cleaning and sanitization process.
- Wipe up spills in the refrigerator immediately.
For more information on Listeria and listeriosis see:
- General Information about Listeria & Listeria and Pregnancy
- Special Handling for Ready-to-Eat Refrigerated Foods: Reducing the Risk of Foodborne Listeria
- Food Safety At-A-Glance: How to Protect Yourself and Your Baby
- CDC Listeria Site
- Multistate Outbreak of Listeriosis
Hold the Raw Sprouts, Please
By Lt. Cmdr. Rajal Mody, MD, MPH, U.S. Public Health Service
Outbreaks caused by eating contaminated sprouts--“sproutbreaks”--have occurred every year in the United States since at least 1995. These episodes have taught us that sprouts are a risky food to eat.
Sprouts were found to be the cause of a devastating outbreak of Shiga toxin-producing E coli infections in Europe this summer. Ultimately, this outbreak caused more than 4,000 illnesses, more than 900 cases of hemolytic uremic syndrome, and 50 deaths.
Why are sprouts a risky food, you might ask? Some people think of them as the ultimate healthy food -- fresh and natural. In fact, raw sprouts can be anything but safe. Lessons from outbreaks have taught us that it is a good idea for people who want to lower their risk for food poisoning to cook raw sprouts or avoid eating them raw.
Here is what we have learned:
Lesson 1: A sprouted seed is a perfect vehicle for pathogens.
A sprouting seed offers as inviting and nourishing an environment as bacteria like Salmonella or E coli could want--and the warm, moist conditions in which sprouts are produced only make matters worse. A single Salmonella organism on the outside of a seed can easily grow to an infectious dose after it has sprouted. The bacteria in or on growing sprouts cannot be washed off. Because even a low dose of Shiga toxin-producing E coli can make you sick, sprouts are a powerful vehicle for transmitting illness. Sprouts have also been the vehicle for Listeria, which causes a very dangerous infection for pregnant women and the elderly.
Lesson 2: Sprouts have caused many outbreaks of illness.
Since sprouts were first recognized as a source of food poisoning in the mid-1990s, they have become one of the "usual suspects" that foodborne disease epidemiologists look for when investigating an E coli or Salmonella outbreak. Since 1998, more than 30 outbreaks have been reported to the Centers for Disease Control and Prevention (CDC), due to many different kinds of sprouts -- alfalfa, bean, clover, and others. In fact, CDC's foodborne disease surveillance systems have identified three sprouts-associated outbreaks since June of 2010 that spread across multiple states.
Lesson 3: It is difficult to grow "safe" sprouts.
Once the potential dangers of sprouts became known, the U.S. Food and Drug Administration (FDA) developed guidance to help sprout growers reduce the risk of germs contaminating sprouts they produce and sell. Many sprouts growers now use practices to decontaminate seeds before sprouting, but no available method has proved completely effective. People who eat raw sprouts, including those who grow their own sprouts, ought to know that they are taking a risk, because contamination typically starts with the seed.
Lesson 4: Sprouts can make even young and healthy people ill.
This is one of the biggest lessons learned from the outbreak in Europe in 2011 and from our experience with outbreaks in this country. Sproutbreaks in the United States mainly affect healthy people aged 20-49 years. A typical victim may be an especially health conscious person in the prime of life. But illnesses from sprouts can be particularly severe in vulnerable populations, such as young children, older adults, pregnant women, and people with compromised immunity.
Lesson 5: It can be hard for those who become ill to remember having eaten sprouts.
We have found in our investigations that people often do not remember having eaten sprouts, because they are often just a garnish or one of many ingredients in a food dish. It is not necessary to eat large quantities of sprouts to get sick. An ill person's inability to accurately recall what they ate sometimes makes it difficult to pinpoint an outbreak of sprouts.
For more information, visit these resources:
CDC Multistate Outbreaks Reports
Avoid Foodborne Illness when Traveling Abroad
by Robin Woo, FDA Center for Food Safety and Applied Nutrition
Traveling to other countries – and staying healthy – requires planning, preparation, self-discipline, and vigilance.
The Food and Drug Administration (FDA) inspects international facilities that make FDA-regulated products to ensure that those products are safe for consumers. So some FDA staffers travel a lot. Here are some precautions they take to keep from getting sick during a trip.
Before You Go
Research. Learn where to find reliable medical care at your destination. Good resources include:
- The Centers for Disease Control and Prevention (CDC) Travelers' Health1
- The CIA World Fact Book2 3
- U.S. Department of State Travel Information4
While in Developing Countries
Avoid tap water. This includes water from the tap and beverages with ice. Don’t drink when brushing your teeth or bathing. In developing countries, water may be contaminated by bacteria, parasites, and viruses that cause hepatitis, cholera, and typhoid fever. Even a small amount of contaminated water can make you ill.
Drink safe beverages.
- Boiled water – One minute of boiling should adequately disinfect most water, but boiling water for 3 minutes is recommended.
- Treated water – Commercial iodine or chlorine tablets provide substantial protection if used according to directions.
- Beverages made with boiled water and served steaming hot (such as tea and coffee).
- Bottled water or canned beverages. Because water on the outside of cans and bottles may be contaminated, they should be wiped clean and dried before being opened.
Water contaminated with fuel or toxic chemicals will not be made safe by boiling or disinfection; travelers should use a different source of water if they suspect this type of contamination.
Avoid raw fruits and vegetables. This includes salads and uncooked vegetables. These may be contaminated or may have been rinsed with unsafe water. Eat only food that has been cooked and is still hot, or fruit that you know has been washed in safe water and you have peeled yourself.
Other foods to avoid include:
- Raw or undercooked meat, poultry, seafood, and eggs
- Unpasteurized milk and milk products, especially soft cheeses
- Prepared food that has been left unrefrigerated for several hours, especially food containing meat, poultry, eggs, and dairy products
- Food prepared by street vendors
Eat safe foods.
- Thoroughly cooked fruits and vegetables
- Fruits with a thick covering (citrus fruits, bananas, and melons) that have been washed in safe water and that you peel yourself
- Thoroughly cooked meat, poultry, eggs, and fish
- Dairy products from large commercial dairies, such as ultra-pasteurized (shelf-ready) milk or hard cheeses
If you get sick
Remember that adequate fluid intake is essential to preventing dehydration. So it’s important to keep drinking safe water even if you have diarrhea. The most common cause of “Travelers' Diarrhea” can be treated with over-the-counter products, used according to directions. Effective drugs that control the frequency of diarrhea include Lomotil, lomodium, and Kaopectate. Find reliable medical help if you have severe abdominal cramps or pain, high fever, blood or mucus in your stool, and/or severe dehydration.
Don't use EnteroVioform. This drug, widely distributed abroad for treating diarrhea, has been linked to nervous system complications.