Which preceding event is commonly reported before GBS?

• A. Recent infection
• B. No preceding event
• C. Vaccination always causes GBS
• D. Chronic illness

Answer: (B)

Guillain-Barré syndrome is driven by an autoimmune process that typically follows a recent infection. The immune system’s response to an infectious agent can cross-react with components of peripheral nerves, leading to the rapid weakness and demyelination seen in GBS. Because of this, the most commonly reported preceding event is a recent infection, often a gastroenteritis or respiratory illness, that occurs in the weeks before onset. The timing is usually within one to three weeks after the infection.

Vaccination can be associated with GBS in rare cases, but it is not a common or guaranteed trigger, and the overall risk is very small. Chronic illnesses are not typically identified as immediate antecedents to GBS. So, the scenario most consistent with how GBS typically begins is a recent infection preceding the onset of symptoms.