They say it is infectious and groups do have outbreaks, but if it was infectious
Why didnt it spread ? Or the trigger spread world wide at the same time?
Why does it skip the larger population?
My guess is because it's highly localized. Lake Tahoe is an interesting example, it was speculated here that it's a form of cyanobacteria or something that can be in the air. It can be viral, fungal, bacterial or anything else. Then some people may be more susceptible to ME than others. It can also be not a single trigger, but two or even three triggers that may be necessary in developing ME. It can be genetics, food, microbiome changes, air quality, building quality, immune system strength, diet type.
I've looked into sick building syndrome a while ago, a lot of people talk about mold induced ME, that theoretically would fit the criteria of infection, but the only infectious part would be mold only. Then the trigger is gone, but the body is stuck in a loop.
Is the cfs/me term just over used in the medical field just as a general term for an unknown sickness?
I think we can't know that for sure since we do not have official ME/CFS biomarker, we can go by symptoms mostly. I suspect a lot of these cases are ME though and that this disease is severly underdiagnosed worldwide. It is said that 20-30 million people globally are affected, but it can be more.
Oh and also welcome to the forum