Guillain-Barré syndrome is not hereditary or contagious. What causes GBS is not known; however, in about half of all cases the onset of the syndrome follows a viral or bacterial infection, such as the following: flu, common cold gastrointestinal viral infection infectious mononucleosis viral hepatitis campylobacteriosis (usually from eating undercooked poultry) porphyria (rare disease of red blood cells) A small number of cases have been known to occur after a medical procedure, such as minor surgery. Guillain-Barré syndrome may be an autoimmune disorder in which the body produces antibodies that damage the myelin sheath that surrounds peripheral nerves. The myelin sheath is a fatty substance that surrounds axons. It increases the speed at which signals travel along the nerves.
