FCGR1A and viral infectious disease: Although nCD64 levels in MP patients were lower than in bacterial infection patients (CD64 ratio: P = 0.002; CD64 index: P = 0.002), they were markedly higher than in healthy control (CD64 ratio: P < 0.001; CD64 index: P < 0.001) and viral infection patients (CD64 ratio: P < 0.001; CD64 index: P < 0.001).