"Food-borne illnesses are more common in summer for a number of reasons," says Linda Harris, PhD, professor in the food science and technology department at University of California Davis. "If the temperature is higher, there is more opportunity for temperature abuse of foods -- that is leaving them in the danger zone, which is anything above 40 and below 140 degrees. In this range, microorganisms that cause food-borne disease can multiply."
From the pasta salad left out all afternoon on the Fourth of July, to a turkey and mayo sandwich in your backpack on a 3-mile hike up a mountain on a warm day, to simply driving from the grocery store to your home in the sweltering heat, summertime foods are a breeding ground for trouble -- and bacteria.
How to avoid it. "There are four basic rules for preventing food-borne illness: cook, clean, chill, and separate -- and these become important during summer," says Harris, who is a scientific communicator with the Institute of Food Technologists.
First, she recommends, use a thermometer when cooking so you know your food is adequately heated.
Second, "when you are outside, it's always best to wash with soap and water. But if you can't, bring sanitizing handy wipes so you can clean your hands after you handle food," Harris tells WebMD.
Third, "if you are going to a picnic, use a cooler where you can maintain food in a cool temperature," says Harris. "Don't use it to make things cold, but to keep things cold. Remember to bring enough ice, as well. If you can't use a cooler, like on a hike, bring foods that don't need refrigeration. Or freeze your foods, so when you are ready to eat them, they're thawed out."
Finally, Harris says, "Keep your utensils and dishes that you use for raw meat separate from those you use to eat."
Warning signs. The warning signs of food-borne illness are the usual suspects, explains Harris: vomiting, stomach cramps, diarrhea, flu-like symptoms, or any combination of these not-so-pleasant symptoms.
"One of the mistakes people make is to assume that the last thing they ate is the cause of their symptoms," says Harris. "While some types of food-borne illnesses take two to six hours until symptoms appear, others take one or three days. So the culprit is not always the last thing you had, even though that's probably what came up."
What to do. Despite best efforts, if you fetch up with something you might suspect is food-borne, keep in mind, "Some food-borne illnesses, such as E. coli O157:H7, can be life-threatening, particularly for young children, the elderly, and those with weakened immune systems," according to the FDA's Center for Food Safety and Applied Nutrition. "Symptoms that are severe or prolonged may need to be treated. People who believe they may have contracted a food-borne illness should call their physician."