Most cases of CFS seem to start out as a "post-viral syndrome". Basically people get a virus, recover from the virus but are left with ongoing fatigue symptoms. After six months it's declared to be CFS (CFS isn't a specific disease, it just declares that you've been fatigued for over six months).
So yes, I think many people who've had CFS would say it's a no-brainer that it was related to an infection. In my case I got "mono" (or glandular fever as we call it here) and it turned into CFS for about seven years. But in the end I recovered and I've been fine for nearly a decade now.
Pretty much mirrors the experience of one of my family members. She contracted mumps and pneumonia in a fairly short time period, then was left with ongoing fatigue. A year on, she's definitely improving, but doing too much leaves her fatigued for days and she sleeps for 18+ hours some days.
A cure (or even treatments to shorten the recovery time) would be wonderful.
So yes, I think many people who've had CFS would say it's a no-brainer that it was related to an infection. In my case I got "mono" (or glandular fever as we call it here) and it turned into CFS for about seven years. But in the end I recovered and I've been fine for nearly a decade now.