The occurrence of homologies between B. burgdorferi flagellae and host molecules has been amply demonstrated [95, 96]. This phenomenon, termed molecular mimicry, explains why an antibody generated against a particular epitope of an infectious pathogen may become an autoantibody, reacting with a homologous epitope in the host and bringing about structural dysfunction or tissue damage. The autoimmune response will continue to attack the host even after clearance of the pathogen from the infected organism. However, autoimmunity by molecular mimicry will only occur if epitopes of the pathogen and of the host are similar enough to allow immunological cross reaction, yet different enough to break immunological tolerance . The homology was assessed by protein BLAST using the search program at OMIM  for short, nearly exact matches. Length = 153, Score = 27.8 bits (58), Expect = 15, Identities = 10/18 (55%), Positives = 15/18 (82%), Gaps = 1/18 (5%). Accession numbers: B. burgdorferi fbrp:1448943; Human interleukin-1 receptor antagonist: 999512.