The causes of acute meningitis are complex, and common causes include infectious and non-infectious factors. 1. Infectious factors: the occurrence of acute meningitis is mostly related to bacterial, viral, fungal and other infectious factors, which lead to inflammatory infection of the membrane tissues around the brain, and thus the onset of the disease. Common causative factors include herpes simplex virus, pneumococcal virus, meningococcus, tuberculosis mycobacterium and so on. 2. Non-infectious factors: The occurrence of secondary meningitis is mostly related to non-infectious factors, such as immunodeficiency diseases, connective tissue diseases, cancer, etc., which may lead to the occurrence of meningitis. When symptoms of meningitis are suspected, it is necessary to go to the hospital immediately for diagnosis and treatment to prevent the condition from being delayed.