The leukocyte count in the cerebrospinal fluid of the normal population is generally 0-8 cells/L, while the number of leukocytes in the cerebrospinal fluid of patients with encephalitis is significantly elevated, and the degree of leukocyte elevation varies between different types of encephalitis. Common types of encephalitis include viral encephalitis, tuberculous meningitis, and septic meningitis. The leukocyte count in the cerebrospinal fluid of patients with viral encephalitis is mildly elevated, reaching 10-100 cells/L, while the leukocyte count in the cerebrospinal fluid of patients with tuberculous meningitis can reach 100-500 cells/L. The leukocyte count in the cerebrospinal fluid of patients with septic meningitis is most significantly elevated, often reaching up to 1000 cells/L. The leukocyte classification in viral encephalitis and tuberculous meningitis is predominantly lymphocytic, whereas in septic meningitis the leukocyte classification is mostly neutrophilic.