Viral meningitis is the most common type of meningitis, an inflammation of the tissue that covers the brain and spinal cord. It is often less severe than bacterial meningitis, and most people get better on their own (without treatment). However, it’s very important for anyone with symptoms of meningitis to see a healthcare provider right away because some types of meningitis can be very serious, and only a doctor can determine if you have the disease, the type of meningitis, and the best treatment, which can sometimes be lifesaving. Babies younger than 1 month old and people with weakened immune systems are more likely to have severe illness from viral meningitis.
Once viruses have gained access to the bloodstream, they can multiply and spread to other parts of the body, including to the spinal cord and brain (the central nervous system). Access to the brain is by blood or nerves. After breaching the blood–brain barrier, the viruses slip inside brain cells. This disrupts, damages and ultimately ruptures the infected brain cells.
Certain viruses have a preference for different areas of the brain. For example, the herpes simplex virus likes to target the temporal lobes located near each ear.
The cells of the immune system rush to the brain and start attacking the viruses. This causes the characteristic brain swelling (cerebral oedema). Both the infection and the attempts of the body to fight the infection are responsible for the symptoms of viral encephalitis.