Soaring summer temperatures make this the peak time for contracting food poisoning. So what can you do to lessen the risk? In basic terms, food poisoning, or gastroenteritis, happens when you eat or drink something contaminated with certain types of bacteria. It can also be viral - both the norovirus and rotavirus are examples - but bacterial infections are by far the most common culprits at this time of the year. Given the right conditions, such as high temperatures, moisture and food to feed from, harmful bacteria multiply rapidly and produce toxins that react with your body, inflaming your stomach and intestines, leading to vomiting, diarrhoea, stomach cramps, dehydration, fever and chills.
The length of time it takes to be affected and the severity of the illness vary from person to person, but the elderly, pregnant women and children are particularly at risk. Young children are especially vulnerable because they do not have as much fluid to lose, and this puts them at a greater risk of kidney failure. While a healthy adult usually recovers from food poisoning with a few days of rest, nutritious food and plenty of water, seeing a doctor as soon as possible is important for anyone who has symptoms.
Doctors advise preparing your own food rather than eating out to lessen the risk, but how can you be sure you are making yourself a healthy meal? "What people often don't realise is that they are carriers of the bacteria that leads to food poisoning," says Dr Lisa Ackerley, who has a PhD in food hygiene. She recently conducted a global survey for the UK Hygiene Council and discovered that in the Middle East, the most common bacteria that led to food poisoning was Staphylococcus aureus.
"This bacteria is found on the skin - on hands, noses and throats - and can be transferred to food, where they grow, releasing a toxin which causes food poisoning often very quickly after eating contaminated food," she says. "Heat doesn't destabilise the toxin, so once it is there, there is no way to make the food safe." This bacteria is found in otherwise clean environments and in around a third of the population. Crucially, it's not bad for you until it gets into your food and starts reproducing. If you have eaten something containing it, you'll certainly know about it. It leads to a rapid onset of the classic symptoms of stomach pain, vomiting and diarrhoea. To avoid any problems, you need to keep clean. Wash your hands before preparing meals, even if it's just a sandwich. Keep your kitchen surfaces clean; use clean cutlery and dishes and keep pets away from the kitchen.
Ackerley says dishcloths are a disaster when it comes to keeping your kitchen clean. "Kitchen cloths are disgusting all around the world; they were the main disseminator of bacteria in every country we measured. They are the antithesis of cleaning." Bacteria thrive on their moisture and when you wipe them over utensils and kitchen surfaces, you are unwittingly introducing them to new habitats. Look carefully at what you buy. Seek out the freshest produce you can, especially in this heat, as food spoils quickly. Don't buy fish that looks slimy or has a strong fishy smell; look for clear eyes and shiny, firm flesh as a sign of freshness. Select meat that is not sweaty, slimy or unpleasant smelling. And with fresh fruit and vegetables, don't buy bruised or unusually soft items that might be on the turn. Check your tins to make sure that they don't have dents in them. Be aware of sell-by dates and check eggs for cracks before you buy - bacteria can get in there, too. All dairy products need to go into the fridge as soon as you get them home.
Once you've got your super-fresh food home, how you store it is important. Fish and meat should be kept at the bottom of the fridge if you are not intending to freeze them. The temperature should be 5°C or below, and all raw food should be covered to avoid the spread of bacteria. If you are marinating meat, leave it in the fridge rather than at room temperature. Throw out anything that smells bad, is past its sell-by date or looks off. Rinse your fruit and vegetables before eating or cooking with them. When eating out, salads are a common cause of food poisoning and best avoided unless you know that the ingredients are washed properly.
For those of us who don't have time to cook from scratch, takeaway seems like a good option. But how do you know the food is safe? Make sure your food is piping hot. Picking it up at the restaurant is a better way of controlling the temperature, ensuring it has not been sitting in a long line of deliveries. As Ackerley explains, it's all in the timing: "If your takeaway has been cooling for up to two hours, it will probably be OK," she said. "Getting a lukewarm takeaway in itself won't make you ill. But if it has been standing for a long time, then you're at risk. I personally would refuse a takeaway that was lukewarm."
Cooked food left at room temperature to cool offers an ideal environment for harmful bacteria to breed, especially if it has been two hours or more. If you can't eat it immediately, cool it quickly in the fridge (some fridges have a quick cool setting just for this purpose), then heat it up to piping hot when you are ready to tuck in the next day. Reheated food, whether it's takeaway or a home-cooked meal, can be a prime breeding ground if it's not served hot enough.
Rice and pizza - items that are often left out at room temperature for far too long - are common causes of food poisoning as they support the growth of the bacillocerius bacteria. The toxin that it produces isn't destroyed by heat, so it can still make you sick even after a zap in the microwave. Don't leave these items out overnight - chilling them in the fridge is the only way to keep them safe. "People don't realise this, but if the Staphylococcus aureus bacteria from your skin gets on to the food, it will multiply," said Ackerley. "If it's left out in warm conditions, say overnight, for up to eight hours, the toxins produced by the bacteria will be at serious levels."
Food poisoning is common but rarely fatal, and you can reduce your chances by being sensible and paying extra attention to your hygiene.