Our findings are consistent with this issue, reporting that some KIR haplotype and HLA alleles and their interaction are more frequent in subjects with acute viral encephalitis and suggesting that this immunological background may influence reactivation of an earlier infection in the majority of cases and neuroinflammatory process subsequent to viral infection driving to symptomatic encephalitis with symptoms that can include headache and fever personality and behavioral changes, seizures, hallucinations, and altered levels of consciousness. The gene discussed is KIR3DL1; the disease is viral infectious disease.