MIF and infectious meningitis: Significantly higher CSF MIF levels were detected in patients with purulent meningitis of known aetiology (8,639 [3,344 to 20,600] ng/l) than in those with purulent meningitis of unknown aetiology (2,209 [1,516 to 6,550] ng/l; Mann Whitney test, P = 0.003), those with lymphocytic meningitis (1,912 [1,302 to 4,105] ng/l; P < 0.001) and those suspected of having meningitis but without evidence of CNS infection (1,472 [672 to 3,447] ng/l; P < 0.001).