Fatigue Syndrome, ChronicFatigueMental FatigueMuscle FatigueXenotropic murine leukemia virus-related virusFibromyalgiaKansasPersian Gulf SyndromeRetroviridae InfectionsDNA ContaminationNeurastheniaMultiple Chemical SensitivityCognitive TherapyGammaretrovirusNeurocirculatory AstheniaSeverity of Illness IndexNevadaQuestionnairesSomatoform DisordersCase-Control StudiesSick RoleChronic DiseaseExercise TherapyPainDepressionDiseases in TwinsPostural Orthostatic Tachycardia SyndromeAcupuncture PointsExerciseEnvironmental IllnessHerpesvirus 7, HumanTreatment OutcomeDyssomniasPrevalenceCentral Nervous System SensitizationDizzinessSleep DisordersInfectious MononucleosisAcupuncture TherapyQuality of LifeTwins, MonozygoticLeukemia Virus, Murine