How can an immune reaction after a mild infection damage peripheral nerves?

An immune reaction can damage peripheral nerves following a mild infection through a process known as molecular mimicry, which is a key mechanism in conditions like Guillain-Barré syndrome.

This occurs when antigens on an infectious agent—such as the bacterium Campylobacter jejuni or certain viruses—closely resemble the molecular structure of components found in peripheral nerve cells. Because of this high degree of similarity, the immune system becomes confused and produces antibodies that target both the invading pathogen and the body’s own nerve tissues.12

This cross-reactive immune response leads to inflammation and the destruction of myelin, the protective fatty sheath surrounding the axon. In some instances, the axons themselves are damaged. This loss of insulation disrupts the conduction of electrical impulses, resulting in symptoms such as muscle weakness, numbness, and, in severe cases, paralysis.2