Diarrhoea, nausea, vomiting, abdominal cramps and, in some cases, fever: during the summer, gastrointestinal disorders seem to become more frequent. Heat, however, is not in itself the cause of gastroenteritis or food poisoning. The rise in cases is mainly linked to environmental conditions and habits that facilitate the proliferation of microorganisms and the contamination of food.
High temperatures make it more difficult to store food properly, especially perishable items. Added to this are travel, outdoor meals, picnics, barbecues and the more frequent consumption of food prepared in advance or transported for several hours.
We discussed this with Professor Maria Rosaria Gualano, Lecturer in General and Applied Hygiene at UniCamillus University.
Gastroenteritis and food poisoning in summer: why do cases increase?
One of the main reasons is the heat. Many bacteria responsible for foodborne infections and food poisoning can multiply more rapidly when food is stored at unsuitable temperatures. If perishable food is left out of the fridge for too long, the risk of contamination and microbial growth increases.
Maintaining the cold chain can also be more difficult during the summer. Groceries may be left in the car, food may be transported without suitable cool bags, or a dish prepared for an outdoor meal may remain at room temperature for several hours.
It is not just a matter of refrigeration. Food preparation can also be a critical stage: hands, utensils and surfaces that are not properly cleaned can transfer microorganisms from one food to another. This is known as cross‑contamination, and it is particularly relevant when raw foods and ready‑to‑eat foods are handled at the same time.
Summer also brings changes in habits. “Eating out more frequently and variations in hydration (watch out for icy drinks and foods consumed too quickly!) can affect the balance of the gastrointestinal system”, emphasises Professor Gualano. In addition to barbecues and picnics, there is an increase in the consumption of cold dishes, salads, sandwiches and preparations that can be transported and stored for several hours. All these situations require greater attention to food safety.
Gastroenteritis and food poisoning: what is the difference?
The terms gastroenteritis and food poisoning are often used interchangeably, but they do not refer to exactly the same condition.
Gastroenteritis is an inflammation of the stomach and intestines that can have various causes, including viruses, bacteria and, more rarely, other microorganisms. Not all cases of gastroenteritis, therefore, are caused by eating contaminated food.
Food poisoning, on the other hand, refers to an illness caused by ingesting food or drink containing toxic substances. There are also foodborne toxin infections, in which certain microorganisms present in food can produce toxins.
The symptoms, however, can be similar and mainly include nausea, vomiting, diarrhoea and abdominal pain. For this reason, it is not always possible to determine the cause based on symptoms alone.
Which foods are most at risk in hot weather
The risk mainly concerns perishable foods and those that require proper storage at low temperatures.
Foods that warrant particular attention include meat, fish, eggs, milk and dairy products, as well as dishes prepared with these ingredients. Even cooked meals, elaborate salads, creams and other ready‑to‑eat preparations can become problematic if stored under unsuitable conditions.
An important point to remember is that contaminated food does not necessarily show obvious signs of spoilage: appearance, smell and taste are not reliable indicators of whether a food is safe.
For this reason, especially on very hot days, it is important to follow the instructions on the label, store food correctly in the fridge and avoid leaving perishable foods at room temperature for long periods.
How to prevent gastroenteritis and food poisoning in summer
Prevention starts with a few simple rules on hygiene and food storage.
Perishable foods must be kept at the recommended temperature and placed in the fridge promptly after purchase or preparation. When transporting food for a picnic, a day at the beach or a trip, using a suitable cool bag can be very helpful.
It is also important to wash your hands thoroughly before preparing or eating food, and to clean the utensils and surfaces used in the kitchen. Particular care should be taken to keep raw and cooked foods separate to avoid cross‑contamination.
Cooking is another crucial step. Meat, fish and eggs must be prepared in a way that allows them to reach temperatures high enough to reduce microbiological risk. Once cooked, food should not be left at room temperature for prolonged periods.
Gastroenteritis and food poisoning: symptoms and what to do
The most common symptoms are diarrhoea, nausea, vomiting, cramps and abdominal pain. In some cases, fever may also occur. The duration and severity of symptoms depend on the underlying cause and the individual’s condition.
One of the main risks associated with vomiting and diarrhoea is dehydration, which can be particularly significant during the summer. “Intense heat and the substantial loss of fluids through sweating can affect the physiology of the intestinal barrier and the balance of the microbiota, leading, in some predisposed individuals, to dysbiosis and increased gastrointestinal sensitivity”, explains Professor Gualano. “Sudden temperature changes caused by air conditioning can also contribute to intestinal discomfort, especially in people with irritable bowel syndrome”.
When gastrointestinal symptoms occur, it is important to replenish fluids and monitor how symptoms evolve. It is advisable to seek medical attention when symptoms are particularly severe or persistent, when signs of dehydration, blood in the stools or high fever appear, or when the affected person belongs to a more vulnerable group.
Summer does not automatically make food unsafe to eat. Heat, improper storage, breaks in the cold chain and poor hygiene are the main factors that create conditions conducive to the proliferation of microorganisms and food contamination. With a few simple precautions, many of the risks associated with gastroenteritis and food poisoning can be reduced.