In the cramped trenches, many parasites thrived. The worst of these were the rodents: rats gorged themselves on human remains, and grew to massive sizes: some reported rats as big as domestic cats. The rats would also sometimes eat the fresh rations of the soldiers, and nibble at the soldiers themselves as they slept or if they were wounded. The rodents would attack a corpse’s eyes, and then burrow themselves into the bodies. They were a terrible problem: as one pair of rats can produce as much as 880 offspring a year, the trenches were soon crawling with millions of them. Some men made pets of the animals as company, but most rats were fearsome creatures.
Another terrible pest of the trenches were lice. Lice as you probably know, are parasites that are hard to get rid of; they bred in uniforms and caused the soldiers to itch. Although this was not know until 1918, lice were also the cause of the dreaded Trench Fever, a painful disease that began as severe pain and a high fever. This disease was caused by the bacterium Bartonella quintana, which the lice spread. Many soldiers succumbed to the disease, and only twelve weeks of recovery away from the trenches would cure it. Other pests of the trenches included frogs, slugs, and horned beetles. Normally, they were not problems, but if you happened to slip on a frog and fall, it could be deadly