From an email correspondence with Adrian, he alludes to his mystery illness:
"An interesting read; I like the pretty bad ass look comment :-) The mystery illness could well have been CFS but back then who knew, it absolutely wiped me out, I literally could not walk around the block. It first struck the week before a big 10km race in Atlanta. I struggled all week, went to the race, toe to toe with Musyoki, out kicked him in a good time 28.29 but a month later it returned with a vengeance and I barely beat Joan Benoit and it stayed with me on and off for a long time. Back then it was unheard of so I and many others had to carry on regardless."