Merck & Co Manuals Merck & Co., Inc., Kenilworth, NJ, USA is a global healthcare leader working to help the world be well. From developing new therapies that treat and prevent disease to helping people in need, we are committed to improving health and well-being around the world.  The Merck Manual was first published in… Read More Fibromyalgia – Musculoskeletal and Connective Tissue Disorders – Merck Manual Professional Edition