Meningitis is an infectious disease of the nervous system, and patients mostly present with fever, headache, and signs of meningeal irritation. The main types of meningitis are viral meningitis, pyogenic meningitis, tuberculous meningitis, and cryptococcal meningitis. The laboratory identification of the cerebrospinal fluid is as follows: the number of cells in the cerebrospinal fluid of patients with viral meningitis is mostly within 50, and the sugar, protein and chloride content are mostly normal. In patients with septic meningitis, the cell count is often above 500, and thousands are common. In tuberculous meningitis and cryptococcal meningitis, the cerebrospinal fluid is basically similar, with cell counts in the tens to hundreds, usually less than 200, with significantly lower sugar and chloride content and higher protein content.