Chronic COVID Syndrome (CCS) and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), often referred to as Long COVID, are among the most misunderstood diseases of our time. Millions of people worldwide are affected by persistent fatigue, cognitive impairment, autonomic dysfunction, and severe stress intolerance-often without a clear diagnosis, effective treatment, and thus without social recognition. This book offers a comprehensive, well-founded, and non-reductionist analysis of post-infectious diseases in the context of Long COVID. It classifies CCS and ME/CFS not as isolated phenomena, but as expressions of systemic dysregulation in which immune responses, the nervous system, vascular function, and energy metabolism interact in complex ways. The focus is on post-exertional malaise (PEM) - a core symptom that has often been overlooked until now, but which fundamentally changes diagnosis, treatment, and rehabilitation. The volume combines current scientific findings with clinical experience and provides detailed insights into symptoms, diagnostic strategies, subtyping, and differentiated treatment approaches. Particular attention is paid to avoiding misdiagnosis, critically evaluating classic rehabilitation models, and the importance of pacing, energy management, and autonomic stabilization. In addition, psychosocial dimensions, stigmatization, work ability, and social participation are systematically analyzed. Bremen University Press has published over 5,500 specialist books in various languages since 2005. February 2026