A study linking chronic fatigue syndrome (CFS) in humans to a family of retroviruses that cause leukemia in mice appears to validate a controversial study published last fall. But far from settling the debate about the role of viruses in the disease, the new findings raise a host of questions about why other scientists, including a team from the US Centers for Disease Control and Prevention (CDC), have failed to find such a link, and about the potential clinical and public health implications. The study was published in August in the Proceedings of the National Academy of Sciences (Lo S-C et al. Proc Natl Acad
Sci U S A. doi:10.1073/pnas.1006901107 [published ahead of print August 23, 2010]).