Isn’t it more spread by body lice than fleas? body lice actually live on clothing, and are relatively easy to control since you just need access to consistent laundry (they’re nowhere near as hard to get rid of as bedbugs or even head lice). You pretty much only see this in the 21st century when there’s a severe lack of housing and access to hygiene in general. Usually seen in refugee camps, concentration camps, prisons, homeless encampments, etc