This is what we found on Wikipedia regarding the Day Fever:

Trench fever (also known as "five-day fever", "quintan fever" (Latin: febris quintana), and "urban trench fever") is a moderately serious infectious disease caused by the bacterium Bartonella quintana and transmitted by body lice. From 1915 to 1918 between one-fifth and one-third of all British troops reported ill had trench fever while about one-fifth of ill German and Austrian troops had the disease. The disease persists among the homeless. Outbreaks have been documented, for example, in Seattle and Baltimore in the United States among injecting drug users and in Marseille, France, and Burundi.

Trench fever is also called Wolhynia fever, shin bone fever, Meuse fever, His disease, and His–Werner disease or Werner-His disease (after Wilhelm His Jr. and Heinrich Werner).