Frightening speed of poison effect

About 10 people a year die in Britain as a result of a severe allergic reaction, anaphylaxis, to wasp and bee stings.

Experts are unsure why some people react in this way to stings, as well as other "triggers" such as peanuts. About one in 100,000 people in Britain is susceptible, many carrying supplies of the drug epinephrine with them so treatment can be administered immediately.

In a "sensitised" person, a sting releases huge quantities of chemicals, including histamine, into the bloodstream. The airways constrict and blood pressure drops, leading to breathing problems.

The tongue and throat swell, effectively suffocating the victim, who then suffers convulsions, multiple organ failure and stroke - sometimes within less than a minute.