LOMITA, Calif. — Enterovirus, a common pathogen that can cause acute respiratory or gastrointestinal infections, may be a factor in chronic fatigue syndrome, according to researchers here. Action Points * Explain to interested patients that this study suggested a link between a common viral infection and chronic fatigue syndrome but the finding requires confirmation. * Explain to patients that no microbiologic cause of chronic fatigue syndrome has been established definitively. Eighty-two percent of stomach biopsy samples from 165 chronic fatigue syndrome (CFS) patients tested positive for enterovirus infection versus 7% of samples from controls (P