Autoimmune demyelinating central nervous system disease in young male with persistently positive fluorescent treponemal antibody absorption test: A case report

• Relapses of autoimmune demyelinating CNS disease are often preceded by infection. • Syphilis may mimic the signs and symptoms of autoimmune demyelinating CNS disease. • Syphilis as inciting event for NMOSD or MOGAD has not yet been reported. • By molecular mimicry and bystander activation, syphilis may have incited MOGA. For NMOSD and MOGAD, onset and relapses are often preceded by non-specific infections, but up until now no known microorganism has been identified to be strongly associated with these conditions. Syphilis as inciting event for NMOSD or MOGAD has only been reported once (Wilcox et al., 2008). This case report examines whether syphilis triggers autoimmune CNS condition or autoimmune CNS disease may cause false positive confirmatory treponemal test. The patient is a 30-year-old who came in with 8-month history of sudden onset spasticity and ataxia of bilateral lower extremities and blindness, confirmed to be transverse myelitis via imaging and optic neuritis by optic coherence tomography respectively. Anti-AQ4 and anti-MOG were negative, however, the patient repeatedly tested positive in FTA-ABS. We suspect that through molecular mimicry and bystander activation, there is a possibility that syphilis may have incited the onset and relapse of his autoimmune CNS demyelinating condition.