Soldiers during World War I suffered from a number of diseases, mostly having to do with sanitation issues. Many of these were the same old diseases that had plagued soldiers for centuries, particularly dysentary. Soldiers also suffered from typhoid, another disease that had always plagued camp life. But they also suffered from some diseases specific to trench life, including fungal infections on their feet known as "trench foot" and various fevers picked up from parasites. The most deadly disease of the war, however, was the flu pandemic that began in the trenches of World War I. Known as "Spanish flu," a misnomer, the disease killed an estimated 20 to 40 million people around the world, and infected about 20% of the world's population.