At the 1st International Workshop on XMRV, which kicked off yesterday at the NIH, one of the most confounding questions was: Why don't the scientists agree?

Conflicting results from different labs looking for XMRV and other related viruses have been at the heart of a debate that started last year, when researchers reported in Science that they found XMRV in a higher proportion of chronic fatigue syndrome patients than healthy people.

The...