Infectious work up was negative for human immunodeficiency virus (HIV) in blood, syphilis serum rapid plasma regain (RPR), babesiosis serum PCR and peripheral smear, WNV IgM in serum, anaplasmosis/ehrlichiosis serum PCR and peripheral smear, varicella zoster virus CSF PCR, HSV CSF PCR, lyme disease serum and CSF serology, enterovirus CSF PCR, California encephalitis virus IgG and IgM [< 1:10 (N = < 1:10)], and Eastern equines encephalitis antibody IgG and IgM [< 1:10 (N = < 1:10)]. The gene discussed is CD40LG; the disease is syphilis.