Foodborne Illnesses

Picnic safety: Avoiding foodborne illness during warm weather

Don't let your summer gatherings be spoiled by foodborne illness. As the outside temperatures begin to rise, so does the number of people who become ill after eating foods that have become contaminated. Disease-causing bacteria multiply more rapidly on warm food, so the safety zone for food quickly declines once it is taken outdoors. You can't always tell if a particular food will cause illness just by looking at or smelling it.

Consider the following guidelines when planning your next summer outing:

Food preparation and handling

• Failure to properly wash hands and food surfaces is a leading cause of foodborne illness. Whenever possible, wash your hands with hot, soapy water before handling food, especially after using the bathroom, changing diapers or interacting with animals. Washing facilities may not be readily available in the outdoors. When packing your picnic basket or cooler, be sure to include wipes or disposable washcloths that can be used for cleaning hands and surfaces that will be in contact with food.
• When preparing food ahead of time for consumption at a picnic, allow enough time for the food to thoroughly chill in the refrigerator before you place it in a cooler. Use an insulated cooler with plenty of ice or ice packs to keep the food below 40 degrees F. Do not store coolers in the trunk of a car. Keep them inside the car, preferably in an air-conditioned climate. Keep perishable foods in a separate cooler away from beverages, since a cooler containing drinks is likely to be opened and closed more frequently. Once you arrive at the picnic, store coolers in a shady spot (under a tree or picnic table) and replace the ice as needed.
• Be certain that raw foods such as hamburgers and poultry do not come in contact with ready-to-eat foods. Wrap raw foods in a leak-proof container, since the juices may otherwise drip onto other food, packed close by in the cooler. Do not allow any utensils, plates and cutting boards that held raw meats to come in contact with cooked foods. Throw them away and use clean plates and utensils for cooked foods. Or, for non-disposable items, wrap them, take them home and run them through the dishwasher (preferably) or wash them in very hot, soapy water by hand before using them again.
• It is not recommended that foods be partially cooked before transporting them to a picnic. Partial cooking allows bacteria to survive and multiply to a point where later cooking cannot destroy them.
• Do not allow food to thaw at room temperature. Foods should be thawed in the refrigerator, under cold water that has been changed every half hour, or in the microwave if the food will be immediately cooked. Thawing at room temperature allows bacteria to multiply on the outer portion of the food while the inside portion continues to thaw.

Food consumption at the picnic and handling leftovers

• Plan to eat take-out foods within two hours of purchase. Otherwise, buy the food ahead of time and refrigerate it until it is well chilled before packing it into the cooler.
• Once the outdoor temperature reaches 90 degrees F, food should not be left out for longer than an hour before it is reheated or refrigerated. If the temperature is below 90 degrees F, food should be left out for no more than two hours. Take only as much food as you will eat, so you won't have to worry about storing leftovers.
• Avoid raw seafood. Raw or undercooked seafood may result in the transmission of a bacterial infection called Vibrio vulnificus. Vibrio vulnificus occurs naturally in marine water and can cause severe illness when transmitted to humans.
• Thoroughly cook all meats. When cooking on the grill, the outside of meats and poultry often appear done while the inner portion remains rare. The following internal temperatures are needed to ensure that disease-causing organisms are killed: ground meat 160 degrees F, steaks 145 degrees F, whole poultry 180 degrees F, and chicken breast and legs to 170 degrees F. To ensure adequate heating, let the coals burn for 20 to 30 minutes before cooking on them.
• Store foods in the cooler immediately after serving. When taking large quantities of food that may be served over more than one meal, pack it in several smaller containers so that all of the food can remain refrigerated until needed. If you are transporting leftovers home, they must remain packed in ice so that the temperature does not go above 40 degrees F. When you get home, check the cooler to be sure that all perishable food is still cool to touch. If so, and you were not gone more than four to five hours, the food is usually still safe to eat. If in doubt, discard.
• Some items are safe to take on a picnic without refrigeration. If you do not wish to be concerned with keeping food safe during a picnic, consider taking the following foods that do not require refrigeration: fresh fruits and vegetables, hard cheese, canned fish or meat, chips, pretzels, bread, peanut butter and jelly, mustard, and pickles.

Food poisoning

Food poisoning is a general term used to describe illnesses people get while consuming contaminated food or water. A number of microorganisms including bacteria, viruses, parasites and fungi can cause food poisoning. Illness can also result from toxins that are released by the microorganisms themselves.

Between 6 million and 7 million people contract some type of foodborne illness, or food poisoning, each year in the United States. Cases of foodborne illness tend to go underreported, because many people assume they have a virus and don't visit a doctor. Symptoms of foodborne illnesses may include nausea, vomiting, diarrhea, fever and abdominal cramps. Other, more severe symptoms may include paralysis, visual changes and difficulty swallowing. Symptoms usually appear four to 48 hours after ingestion of a contaminated food but they can be delayed for as long as two weeks.

In most cases, the symptoms of food poisoning are self-limiting. Although they can be quite uncomfortable, a full recovery is expected. In some cases, however, infections from contaminated food can be dangerous and life-threatening. Pre-existing illness or health conditions can contribute to the severity of illness. If you suspect food poisoning, see a doctor.

The types of bacteria that are responsible for the majority of reported cases of foodborne illness include:

• Clostridium botulinum: This organism causes botulism, a rare but very dangerous form of food poisoning. It is usually associated with low-acid canned foods that have been improperly processed or stored.

• Campylobacter jejuni: This type of bacteria most commonly causes diarrhea, and is associated with raw and undercooked meat and poultry, raw milk and untreated water.

• Clostridium perfringens: This form of bacteria is commonly found in food buffets, when adequate temperatures of 140 degrees F or hotter are not maintained.

• E coli: This organism normally resides in the intestine without causing harm. Some strains cause diarrheal illness. However, one type of E coli, 0157:H7, produces a deadly toxin and causes illness. Common sources include undercooked or raw hamburger, raw milk, and produce.

• Listeria: This type of bacteria is found in milk, raw vegetables, soft or semi-soft cheeses, meat and poultry. Listeria can grow slowly at refrigerated temperatures.

• Salmonella: Salmonellosis is currently the most common bacterial foodborne infection in the U.S. It can be found in a variety of foods but is most frequently associated with poultry, meat, eggs, and unpastuerized milk.

• Shigella: Poor hygiene causes shigella to be easily passed from person to person. Common sources of this infection include salads, dairy products, milk, and unclean water.

• Staphylococcus: Frequently referred to as staph, these bacteria are carried in the nose, throat and skin by humans. Ordinary cooking does not kill the gastrointestinal toxins made by staph, so good personal hygiene when cooking is essential to prevent this infection.

Related Articles Bacterial Infections

External Sources www.foodsafety.gov US Food and Drug Administration. Center for Food Safety and Applied Nutrition. Foodborne Pathogens, Microorganisms and Natural Toxins Handbook

This article was reviewed and updated June 2007.

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