"Ewwww, girls have cooties!" takes on a completely different meaning when you know what "cooties" really are.
Typhus was a horrible disease. In the trenches, epidemic typhus caused a fatality rate between 10 and 40% depending on the outbreak, despite treatment (since antibiotics were not around yet). In WWI and WWII, millions of deaths, most civilian, occurred because of typhus outbreaks. Anti-typhus campaigns were almost completely geared towards the military until after 1945, when serious eradication campaigns began throughout Europe. Notable casualties of typhus - Anne Frank and her sister Margot both succumbed just weeks before Allied troops liberated the camp.
**Don’t confuse typhus with typhoid fever! They occurred in the same areas a lot of the time, but are completely different diseases, with completely different methods of transmission.