I: Certain infectious and parasitic diseases

A80-A89: Viral infections of the central nervous system

Viral infections of the central nervous system (CNS) are a group of conditions caused by various types of viruses that invade the CNS, which includes the brain and spinal cord. These infections may be spread through direct contact, ingestion, or even through the air by coughing or sneezing. Common symptoms usually begin with fever, headache, and fatigue, which may progress to more severe symptoms like confusion, seizures, or paralysis, depending on the specific infection and its location within the CNS. This progression can occur rapidly over hours to a few days, or may be slower, over weeks. The severity and course of symptoms can vary greatly, from mild and self-limiting to severe and potentially fatal, depending on the virus involved and the individual's overall health.