Immersion foot

Immersion foot, archaically trench foot, is a medical condition caused by prolonged exposure of the feet to damp and cold. It was a particular problem for soldiers in trench warfare during the winters of World Wars I and II and in the Vietnam conflict.

Immersion foot occurs when feet are cold and damp while wearing constricting footwear. Unlike frostbite, immersion foot does not require freezing temperatures and can occur in temperatures up to 60° Fahrenheit (about 16° Celsius). Immersion foot can occur with as little as twelve hours' exposure. Affected feet become numb and then turn red or blue. As the condition worsens, they may swell. Advanced immersion foot often involves blisters and open sores, which lead to fungal infections; this is sometimes called jungle rot. If left untreated, immersion foot usually results in gangrene, which can require amputation. If immersion foot is treated properly, complete recovery is normal, though it is marked by severe short-term pain when feeling is returning. Like other cold injuries, immersion foot leaves sufferers more susceptible to it in the future.

Immersion foot is easily prevented by keeping the feet warm and dry, and changing socks frequently when the feet cannot be kept dry. British soldiers in World War I were advised to keep multiple pairs of clean socks on hand, and change them at least three times daily. During World War I, trench soldiers were provided with whale grease and told to apply it to their feet to reduce the prevalence of this condition; the idea was to make the feet waterproof. It was also discovered that a key measure was regular foot inspections by officers.

Trench foot made an unwelcome reappearance in the British Army during the Falklands War, in 1982. The causes were the cold, wet conditions and the DMS boot, which was insufficiently waterproof. Large numbers of soldiers were incapacitated by the condition; there were rumours that, if the war had not ended when it did, the British advance would have stopped.