West Nile virus induces a post-infectious pro-inflammatory state that explains transformation of stable ocular myasthenia gravis to myasthenic crises.

West Nile virus (WNV) infection has been reported to promote myasthenia gravis (MG) and various other diseases that have a presumed autoimmune pathogenesis. Molecular mimicry between WNV proteins and host proteins has been postulated as the major mechanism for WNV-triggered breaking of immunological self-tolerance. We present a patient with stable ocular MG and positive anti-acetylcholine receptor antibodies who progressed to myasthenic crisis after WNV neuroinvasive disease. In this case of stable autoimmune disease with proven auto-antibodies, transformation to generalized disease cannot be attributed to molecular mimicry, which requires that an immune response first be generated against an infectious agent. Rather, the evidence supports the concept of a post-infectious pro-inflammatory state that may contribute to the amplification and promotion of autoimmune disease in some WNV survivors.