The warmth of the summer sun can do wonders for your spirits, but it can also promote the growth of dangerous bacteria in food. You can keep the good memories of summer picnics by preventing food poisoning and the symptoms that could upset your summer fun.

Food poisoning symptoms include diarrhea, vomiting, stomach ache, and possibly fever. Most cases of food poisoning are mild and don't require hospitalization. However, if symptoms last for more than two or three days, or if you have a number of the symptoms, see your doctor,

"The most important thing to do is to drink plenty of liquids so you don't become dehydrated. Using a sports drink that contains water, salt, and sugar can help keep liquid in the body," says Dr. Phyllis Stumbo, research nutritionist at the University of Iowa College of Medicine.

Common food poisoning bacteria include salmonella, most often found in meat and eggs that have not been thoroughly cooked; E. coli bacteria, found in meat and dairy products that have not been thoroughly cooked or pasteurized; and botulism, found in improperly canned vegetables.

Food poisoning can be prevented by following a few simple steps, Stumbo says, noting that bacteria need three things to grow: heat, water, and time. Heat is especially bad for eggs. "Carefully refrigerate foods that contain lightly cooked eggs, including cream pies. Even hard-boiled eggs and egg rich foods should not be left out of the refrigerator for more than two hours. Don't eat raw meat or eggs or drink unpasteurized milk."

You can prevent food poisoning in home-canned vegetables by pressure-cooking vegetables before canning. That kills the spores that can produce the deadly toxin that causes botulism. Boiling vegetables before eating them also kills the toxin. A swollen or bulging can is a signal that something dangerous may be growing inside, and should be discarded.

Even refrigerated foods can have bacterial growth, so examine bottles and packages carefully, especially those that have been in the refrigerator for several days or weeks. If bacteria is growing inside, you can tell by listening closely when you open the lid or package. If you hear gas escape, don't use the food.

"The best rule is: If in doubt, throw it out!" Stumbo says. "And before handling food, always wash your hands, wash your hands, wash your hands!"

If you have food poisoning symptoms, call your doctor. If you are concerned about food safety, call the U.S. Department of Agriculture hotline at 800-535-4555,