CXCL13 and Lyme disease: The major findings of Rupprecht et al. study was that high levels of CXCL13 could be found in the CSF of patients with the two most common spirochetal CNS diseases, NB and NS, but the elevated CSF CXCL13 levels in patients with neurosyphilis were lower than in patients with neuroborreliosis (Rupprecht et al. 2007).