With the heat and so many choice picnic spots enticing us to lawns and beaches, many will forget to pack a little extra prevention in their food baskets. No, I’m not talking about water balloons, but rather knowledge about preparing and toting perishables before spreading them out on a blanket.

According to the U.S. Department of Health and Human Services, food poisoning affects several million people a year in the United States, with more than half of the cases occurring between May and September. In other words, that warm, yellow sun that seems to invite eating al fresco is no friend to those pretty deviled eggs you towed along. In the two hours it takes for your skin to bronze, the exposed eggs have already begun festering with dangerous bacteria that can create more gastrointestinal distress than if you washed down a dozen deep-fried Twinkies at the Del Mar Fair.

And that hand you used to gingerly apply raw chicken to the grill – leave it unwashed and you could introduce a touch of Staphylococcus aureus bacterium to your body when opening your next can of beer. Cross contamination between perishable and non-perishable foods, experts say, is the most common cause of summer food poisoning.

Below are a few common-sense tips that will prevent uninvited “guests” from spoiling your picnics:

Bring moist towels or soap and water to clean your hands and table surfaces often. The last group that used your picnic table may have left behind a few invisible enemies that can easily make their way into your food spread.

For foods that are to be served cold, such as meat or poultry salads, make sure that all of the cooked ingredients are cooled first before tossing them together. Then seal the completed dish into a shallow, airtight container and keep it chilled.

Bacteria begin to multiply between 40 and 140 degrees Fahrenheit – and ice is cheap. So pack plenty of it in a well-insulated cooler to keep the temperature inside at below 40 degrees. And be sure to transport the food-stocked cooler in the back of your air-conditioned car instead of a hot trunk.

In other words, bring two coolers – one for ready-to-eat foods and beverages, the other for raw meats. Also, pack uncooked foods according to how you’ll use them. Items you plan on pulling out last should go to the bottom of the cooler.

Always marinate foods in the refrigerator, and don’t reuse the marinating liquid on other foods unless it’s boiled.

Pack condiments in them rather than taking whole jars. You’ll not only thwart contamination, but you’ll spare your main supplies of mayonnaise, mustard and relish from looking like a smeared paint palette at the end of the day.

The rules of thumb are to cook hamburger to at least 160 degrees and chicken breasts to 170 degrees. Never partially cook meat or poultry at home to finish cooking later at the picnic site.

Tupperware lids not only keep foods cool longer, but they are also your only safeguards from nature’s nastier elements that can land disease into that creamy potato salad you made when nobody is looking.

Any food that has been removed from refrigeration for more than two hours should be thrown away. If you put those foods back into the cooler, the bacteria will stop multiplying, but they have likely grown to large enough numbers to make you ill when eaten later.