However, procalcitonin seems to be a valuable tool for discriminating the causative factor of meningitis as, since 1997 and 1998, two French studies showed that, using a cut-off range of 0.5–2 ng/mL, S–PCT had 100% sensitivity and specificity in discriminating bacterial from viral meningitis [51]. The gene discussed is CALCA; the disease is viral meningitis.