Central Nervous System (CNS) infections are caused by bacteria, viruses, fungi, helminths, with several clinical aspects. Studies in the literature generally focus on a single patient type, and no experiences have been reported in which immunosuppressed and immunocompetent adult and pediatric patients were simultaneously examined. Our study will include all possible patient types (immunocompetent adults, immunocompetent pediatric patients, and subjects immunosuppressed by co-softness), to try to more precisely define the clinical and population characteristics of patients who have had an episode of CNS viral infection. These indications may be useful in the future to more specifically guide diagnostic investigations on patients considered at risk.

The objectives are: 1) to verify whether the different categories of patients present a different distribution of etiological agents (Citomegalovirus, Herpes Simplex Virus 1, Herpes Simplex Virus 2, Human Herpesvirus 6, Varicella Zoster Virus, Epstein-Barr Virus, Enterovirus) for CNS infection; 2) to verify whether the course and clinical manifestations of the disease can be associated with the identified etiological agent and the type of patient; 3) to describe the results of instrumental tests (EEC and/or MRI and/or CT) in patients who tested positive for a neurotropic virus responsible for the infection.

Inclusion Criteria:

• Patients whose CSF was analyzed for HSV-1, HSV-2, VZV, EV, EBV, CMV and HHV-6 between 01/01/2014 and 31/12/2024.
• Obtaining informed consent.

Exclusion Criteria:

- None

The study will include cases from various centers in the Bologna metropolitan area, involving adult and pediatric patients, including newborns, whose CSF was analyzed at the Microbiology Unit of the IRCCS AOUBO, Policlinico di Sant'Orsola, between January 1, 2014, and December 31, 2024.