If you are one of the five million radio listeners who follow BBC Radio 4’s popular soap The Archers, you probably know more about E. coli now than you did when this pathogenic bacteria erupted earlier in the year, causing several deaths and millions of pounds worth of Spanish salad vegetables to be destroyed.

For the uninitiated, the latest dramatic storyline in this soap about everyday country folk has put the future of Bridge Farm Dairy in jeopardy — and all because dairy worker Clarrie Grundy returned to work too early while still harbouring the E. coli bacteria. She assumed it was just a tummy upset caused by a dodgy hamburger, and having rested over the weekend returned to work assuming all was well. But it wasn’t.

The result was a catastrophe, with two children in hospital, temporary closure of the dairy and the possibility of a successful organic ice cream and yoghurt business losing all its regular customers.

Now that we are enjoying some reasonably warm weather, this storyline is a timely reminder that great care should be taken when using the barbecue or leaving uncooked food exposed to warm conditions.

It also reminds us all that anyone who has suffered from food poisoning (identified by sickness, a rise in temperature and diarrhoea, which in the case of E. coli often appears to be bloody) should avoid preparing food for others until they have been given the all-clear from their doctor.

This is something that the long-suffering Clarrie Grundy failed to do. She just assumed she was better, and returned to work. Although Clarrie followed all the stringent hygiene rules set out by the practical and stoical Pat Archer who runs the dairy, at the time she returned to work Clarrie was a carrier. Strains of the bacteria were still in her system. It was more than a week before she was declared free of the bacteria by the environmental health officers who appeared in Ambridge the moment the outbreak was traced to Home Farm’s ice cream.

Of course, there are other ways of contracting a food-borne illness. Leaving uncooked products in the sun — which would have been harmless if they had cooked from cold — is one of the main reasons why food poisoning occurs. Because bacteria are not visible, and don’t usually affect the taste of food, we are not always prepared for an illness that can follow a great meal.

Bacteria such as Campylobacter can be found in raw poultry and meat, unpasteurised milk and untreated water. Pets with diarrhoea can also be a source of infection. Salmonella can be found in raw poultry and meat, eggs and raw unwashed vegetables and Listeria is found in the soil — therefore in unwashed fruits and vegetables, and soft cheeses. And, as we are now aware, bacteria such as E. coli can be transferred to food by anyone still carrying the bacteria.

To avoid any of these nasties affecting your food, the rules are simple — keep hot food hot (above 140F) and cold food cold (below 40F). Keep all surfaces used for food preparation spotlessly clean, particularly after preparing raw food, store uncooked foods on the lower shelves of the refrigerator to avoid their juices weeping on to other foods stored there and wash your hands with soap and water after using the lavatory or before preparing raw food.

No food should be kept exposed in warm summer sunshine. In warm conditions, bacteria can multiply from one to more than four million in just eight hours as their numbers double every 20 minutes.

Yes, heat can kill bacteria, but raw food has to be exposed to a high heat for at least ten minutes — sometimes more — before rendered safe. Always make sure that the inside of the food is piping hot and never reheat cooked meat that has been left in the sun or reheat anything more than once.

A very rare steak or hamburger might be the favourite of the day, but bacteria within the steak will flourish if it is not cooked for long enough. This does not mean that all steaks and hamburgers should be cooked to death, but vigilance is called for. It’s so easy to assume a big, fat hamburger is done when the barbecue flames have created a dark brown crust on the exterior. Transporting food safely for an open-air picnic should be taken seriously too. Fortunately there are now some splendid picnic packs on the market that keep food at the right temperature, and freezer blocks can also be added to a basket of food to keep it cool. Picnic food purchased in sealed plastic packs is best transported unopened and do not be tempted to swill a dirty glass in the river water and reuse it.

It is not my intention to put you off summer parties — far from it. This is just a timely reminder that certain rules ought to be obeyed if you want to ensure everyone has a good time.