How to Prevent Foodborne Illnesses That Cause Gastroenteritis in the Summer: Monitoring Time and Temperature Is Essential

Carelessness or a lack of attention to times and temperatures—especially when the cold chain is broken—are among the most common mistakes made in food handling and storage during the summer. These mistakes can lead to foodborne illnesses that cause gastroenteritis, such as campylobacteriosis, caused by Campylobacter, a bacterium commonly found in raw poultry; or salmonellosis, the second most common foodborne illness, caused by bacteria of the genus Salmonella, which is associated with the consumption of eggs and egg products, although it can also be present in meat and vegetable products.

"Improper handling of these foods, cross-contamination, or undercooking can facilitate the spread of these bacteria. High temperatures promote the rapid multiplication of these bacteria when the cold chain is broken or foods are left at room temperature for too long," explains Roncesvalles Garayoa, professor at the School of Pharmacy and Nutrition and a researcher at the Institute of Nutrition and Health at the University of Navarra.

So far this year, according to data the Navarre Institute of Public Health, the region has recorded 205 cases of salmonellosis, more than double the usual number. In Spain, the latest report on foodborne outbreaks from the Carlos III Health Institute (ISCIII) recorded 854 outbreaks caused by food consumption—including water—in 2024. Historically, the summer months have seen the highest Issue foodborne illnesses.

Prevention Inside and Outside the Home

Garayoa warns of changes in habits that occur specifically in the summer—such as eating out, picnics, or barbecues—when hygiene measures also tend to be relaxed. This combination of high temperatures and less control over food storage promotes the growth of microorganisms in food. “The golden rule is to strictly maintain the cold chain. To do this, it is essential to use a cooler or an insulated bag—which are designed to maintain temperature but not to cool hot or room-temperature food—and to fill it with enough ice packs. Additionally, a very effective method is to place food and beverages that have already been chilled in the refrigerator at home,” she notes.

It is recommended to store food in tightly sealed, airtight containers to prevent juices from one item from contaminating others; open the cooler as little as possible; and keep food and beverages separate in different coolers. "In addition, it is best to keep them out of direct sunlight and store them in a cool or shaded area. The most perishable foods, such as cooked meats, dairy products, cold cuts, or prepared salads, should remain refrigerated until ready to eat."

At home, prevention involves following a series of measures such as washing your hands frequently and keeping surfaces clean; separating raw foods from cooked or ready-to-eat foods; cooking food thoroughly; and maintaining safe temperatures. Garayoa points out that proper refrigeration at home is essential: “Cooked food should not be left at room temperature for more than two hours (or one hour if the room temperature is very high). Likewise, leftovers should be stored in the refrigerator as soon as possible in shallow containers to facilitate rapid cooling, and you should ensure that the refrigerator is set to a temperature of 4°C or lower. Finally, it’s important to remember that contaminated food doesn’t always show changes in smell, taste, or appearance. If you have any doubts about its condition or freshness, the safest option is not to eat it.²

As he explains, foods with a high water content and high protein content pose a greater risk of causing infections, such as ground meat, fresh fish, shellfish, eggs, certain sauces, and prepared dishes that are consumed at leave and require the cold chain to be maintained at all times. Conversely, foods that best withstand heat are those with leave water leave , such as nuts, bread, or salty snacks, since microorganisms need water to grow. Highly acidic foods, such as pickles, or those with a high sugar concentration, such as jams, also provide an unfavorable environment for the development many microorganisms. “However, no food is completely Exempt if it is handled or stored improperly,” he concludes.