STANFORD, Calif., Jan. 9 A U.S. study suggests valganciclovir, a drug often used in treating diseases caused by human herpes viruses, may help with chronic fatigue syndrome.The researchers said they treated 25 patients during the last three years and 21 have responded with significant improvement that was sustained even after going off the medication at the end of the treatment regimen, which usually lasts six months.The first patient has now been off the drug for almost three years and has had no relapses, according to Dr. Jose Montoya and postdoctoral scholar Andreas Kogelnik of the Stanford University School of Medicine.Valganciclovir is normally used against diseases caused by viruses in the herpes family, including cytomegalovirus, Epstein-Barr virus and human herpes virus-6.The findings have been published in the Journal of Clinical Virology and will be presented at the biannual meeting of the International Association for chronic fatigue syndrome in Fort Lauderdale, Fla.Copyright 2007 by UPI