Brain infections are very serious and can be fatal. They can be caused by:
Viruses (most common)
Bacteria
Fungi or parasites (rare)
Infections that involve only the brain are called encephalitis Encephalitis Encephalitis is inflammation of your brain, usually caused by an infection. Encephalitis can be caused by a virus directly infecting your brain or when a virus or a misguided immune reaction... read more . Infections that involve the layers of tissue (meninges) that cover the brain and spinal cord are called meningitis Viral Meningitis Meningitis is an infection of the thin layer of tissue that covers your brain and spinal cord. This layer of tissue is called the meninges. In viral meningitis, the infection is caused by a... read more . But encephalitis can spread and cause meningitis. And sometimes meningitis spreads to cause encephalitis.
Brain infections from a virus usually affect your whole brain. Brain infections caused by bacteria sometimes cause a pocket of pus, called a brain abscess Brain Abscess An abscess is a pocket of pus. A brain abscess is a pocket of pus in your brain. One or more brain abscesses can form when an infection spreads from somewhere else in your body An abscess puts... read more .
How do infections get in your brain?
Infections usually start somewhere else. They can get to your brain and meninges in several ways:
From an infection nearby, such as in your teeth, sinuses, or ears
Through your blood from another part of your body
Directly from the outside, for example, through a skull fracture or during brain surgery
Infections that spread through your blood sometimes come from bug bites, particularly from mosquitoes and ticks.
What are the symptoms of a brain infection?
Brain infections keep your brain from working properly. You often have:
Headache
Confusion and trouble thinking clearly
You may not act like yourself. Severe infections can cause seizures Seizure Disorders Seizures are changes in the brain's electrical signals. A seizure disorder is a problem that causes a person to have seizures. The brain is made up of nerve cells. Nerve cells talk to each other... read more and make you go into a coma Stupor and Coma Stupor is unresponsiveness from which a person can be aroused only by vigorous, physical stimulation. Coma is unresponsiveness from which a person cannot be aroused and in which the person's... read more , have trouble breathing, and sometimes die.
How do doctors diagnose brain infections?
Doctors usually do:
CT Computed Tomography A CT scan uses a large machine shaped like a large donut to take x-rays from many angles. A computer then takes the x-rays and creates many detailed pictures of the inside of your body. Each... read more
or MRI Magnetic Resonance Imaging (MRI) MRI is a test that uses a machine with a powerful magnet to make pictures of the inside of your body. A computer records changes in the magnetic field around your body. The computer then uses... read more 
How do doctors treat brain infections?
Doctors try to treat the cause of the infection. Antiviral drugs or antibiotics work for some infections but not all. Doctors also give medicine to relieve symptoms. If needed, they may put the person on a ventilator Ventilators Ventilation is the same thing as breathing. It's the movement of air into and out of your lungs. Sometimes your breathing needs to be assisted by a ventilator. A ventilator is a machine that... read more or give treatments to support the person's blood pressure.
