Fly feet, under-cooked burgers and room-temperature potato salad aren’t the only food poisoning threats on the menu for Memorial Day weekend gatherings.

Pools, puppies, and playgrounds are just three of the other potential pathogen vectors that can bring bacteria to the table. But, as with so many foodborne foes, a few simple precautions provide a powerful defense. Mothers have been harping about since before indoor plumbing was invented — wash your hands.

Oft’ ignored vectors
Bags of chips, fruit platters, condiments and other foods can be cross-contaminated by people if they don’t wash their hands after swimming. In fact, pools are particularly bad for norovirus, and ponds, lakes, and creeks are a breeding ground for E. coli. Oceans are home to a menu of bad bugs while digging clams, making sandcastles, fishing, and playing with domestic and farm animals are all a risk with wherever your festivities take you.

Touching playground equipment in parks and backyards with bird poop doesn’t belong on your hamburger or hotdog bun. Bottomline, wash your hands correctly and take hand sanitizers so it can be used twice before eating and preparing food. The CDC suggests allowing your hands to air dry between and after back-to-back applications.

The Fab Four of food safety: Clean, Separate, Cook, Chill 

Start with clean hands
Sound repetitive yet? Good. The first step to preparing a safe and healthy meal is clean hands. Always wash your hands before and after handling any foods. Be sure to wash them during food preparation, too, when switching from handling raw meat to chopping raw vegetables for a salad.

When you’re eating outdoors, you may not have access to soap and water. Experts recommend using hand sanitizer with a minimum of 60 percent alcohol when clean running water isn’t readily available. If soap and water are not available, use hand sanitizer and paper towels and then use hand sanitizer again, allowing your hands to air dry before eating or handling food.

Also, clean and sanitize coolers, grills, grilling utensils, picnic baskets and tote bags because they can be a breeding ground for bacteria.

No food should be held in the danger zone, which begins at 41 degrees F and ends at 140 degrees F.

Separate raw meats, poultry, and seafood from RTE foods
If you are planning to cook for the holiday weekend — inside or out — separate raw meats, poultry, and seafood from other ready-to-eat (RTE) foods. Use one cooler for raw meats and poultry and another for RTE foods such as fruits, vegetables, cheese, and desserts. Take two sets of plates and utensils for handling raw meats and for serving cooked foods to limit the chances of cross-contamination.

Use a food thermometer
All food must be cooked to a safe internal temperature to kill harmful bacteria, and a food thermometer is the only way to make sure that food has reached this temperature. Remember to pack the food thermometer and download a free Is My Food Safe? mobile app for a complete list of cooking temperatures.

Keep the cooler cool
Pack perishable food in a cooler to help it stay cold. Keep the cooler in the shade with the lid closed. Freeze bottles of water or juice boxes for a refreshing treat that will also help keep foods packed around them cooler. It’s also a good idea to pack a thermometer in the cooler to make sure that it stays at 40 degrees F or lower.

Refrigerate or toss after two hours — or 60 minutes if it’s really hot outside.
When everyone’s had a turn in the chow line, return perishable foods to coolers or refrigerators within two hours. Experts say cut that to one hour if the ambient temperature is higher than 90 degrees F. The clock starts as soon as your food is taken off the grill or out of the cooler. Set an alarm to keep track of the time.

Hot foods should also be properly cooled down and popped into leftover containers for use in the cooler to keep bacterial growth under control. Be sure to reheat leftovers to proper temperatures to kill pathogens.

Uninvited guests
Fruit flies have long been annoying, unwanted, swat-able guests at indoor and outdoor events. Under a closer lens, fly barf and poop have been associated with human illness. Now, researchers have found that fly footprints are just as, if not more, dangerous.

Fruit fly
Image courtesy of NASA

Scientists on three continents studied the concentrations of different bacteria on various parts of the insects’ bodies; collecting houseflies and blowflies from urban, rural and natural settings.

“Legs and wings displayed the largest microbial diversity and were shown to be an important route for microbial dispersion,” according to research published Nov. 24 of last year.

“Despite a small body mass, the legs + wings fraction yielded the highest diversity of bacterial species.”

As most studies have looked at the gastrointestinal tract, without addressing the role of the outer body of flies, it can be hypothesized, according to the researchers, that the fly feet, wings, mouthparts and other body surfaces constitute the main route of microbial dispersal by mechanical vectors.

Another research project, with a report published Feb. 23, was able to examine flies’ ability to transfer bacteria from a contaminated source, food, or waste to surfaces or ready-to-eat food.

“Fruit flies were shown to be capable of accumulating approximately 2.9 × 103 log CFU of E. coli per fly within 2 (hours) of exposure to a contaminated food source,” according to the report. And, levels of bacteria did not decrease over an observation period of 48 hours.

“These data, coupled with the feeding and breeding behavior of fruit flies in unsanitary areas of the kitchen and their propensity to land and rest on food preparation surfaces and equipment, indicate a possible role for fruit flies in the spread of foodborne pathogens,” according to the study.

Help is on the line and online
If you have food safety questions, FSIS recommends contacting “Ask Karen,” the agency’s 24/7 virtual representative, at, or call the USDA Meat and Poultry Hotline and speak with a live representative, in English or Spanish, at 1-888-674-6854. You can also visit for safety information on all types of foods.

(To sign up for a free subscription to Food Safety News, click here.)