Encephalitis is inflammation of the brain that causes problems with brain and spinal cord function. It is often caused by a viral infection, though bacteria and other non-infectious conditions can also cause it. Symptoms include headache, neck stiffness, sleepiness, seizures, and changes in mental status. Diagnosis involves neurological exam, imaging like MRI, and tests of cerebral spinal fluid. Treatment focuses on reducing swelling, controlling infections and seizures, and providing supportive care. Prevention involves vaccination, hygiene, and protection from mosquitoes and ticks that can transmit viruses.

1. ENCEPHALITIS
DEFINTION :-
Encephalitis is a term used to describe inflammation of the brain. This condition
causes problems with the brain and spinal cord function. The inflammation causes
the brain to swell, which leads to changes in the person's neurologic condition,
including mental confusion and seizures.
INCIDENCE:-
Affecting aboutonein 200,000 peopleeach year in the U.S. Encephalitis occurs
in 1 in every 1,000 cases of measles.
HSE, the most common cause of sporadic encephalitis in Western countries, is
relatively rare; the overall incidence is 0.2 per 100,000, with neonatal HSV
infection occurring in 2-3 per 10,000 live births.
CAUSES:-
The exact cause of encephalitis is often unknown. But when a cause is known, the
most common is a viral infection. Bacterial infections and noninfectious
inflammatory conditions also can cause encephalitis. There are two main types of
encephalitis:
 Primary encephalitis. This condition occurs when a virus or other agent
directly infects the brain. The infection may be concentrated in one area or
widespread. A primary infection may be a reactivation of a virus that had been
inactive after a previous illness.
 Secondaryencephalitis. This condition results from a faulty immune system
reaction to an infection elsewhere in the body. Instead of attacking only the
cells causing the infection, the immune system also mistakenly attacks healthy
cells in the brain. Also known as post-infection encephalitis, secondary
encephalitis often occurs two to three weeks after the initial infection.

2. WAY OF TRANSMISSIONOF INFECTION:-
West Nile virus transmission cycleOpen pop-up dialog box
The viruses that can cause encephalitis include:
 Herpes simplex virus (HSV). Both HSV type 1 - associated with cold sores
and fever blisters around your mouth and HSV type 2 - associated with genital
herpes can cause encephalitis. Encephalitis caused by HSV type 1 is rare but
can result in significant brain damage or death.
 Other herpes viruses. These include the Epstein-Barr virus, which commonly
causes infectious mononucleosis, and the varicella-zoster virus, which
commonly causes chickenpox and shingles.
 Enteroviruses. These viruses include the poliovirus and the coxsackievirus,
which usually cause an illness with flu-like symptoms, eye inflammation and
abdominal pain.
 Mosquito-borne viruses. These viruses can cause infections suchas West
Nile, La Crosse, St. Louis, western equine and eastern equine encephalitis.
Symptoms of an infection might appear within a few days to a couple of weeks
after exposure to a mosquito-borne virus.
 Tick-borne viruses. The Powassanvirus is carried by ticks and causes
encephalitis in the Midwestern United States. Symptoms usually appear about a
week after a bite from an infected tick.
 Rabies virus. Infection with the rabies virus, which is usually transmitted by a
bite from an infected animal, causes a rapid progression to encephalitis once
symptoms begin. Rabies is a rare cause of encephalitis in the United States.
 Childhood infections. Common childhood infections such as measles
(rubeola), mumps and German measles (rubella) used to be fairly common

3. causes of secondaryencephalitis. These causes are now rare in the United
States due to the availability of vaccinations for these diseases.
RISK FACTORS:-
Anyone can develop encephalitis. Factors that may increase the risk include:
 Age. Some types of encephalitis are more common or more severe in certain
age groups. In general, young children and older adults are at greater risk of
most types of viral encephalitis.
 Weakenedimmune system. People who have HIV/AIDS, take immune-
suppressing drugs or have another condition causing a weakened immune
system are at increased risk of encephalitis.
 Geographicalregions.Mosquito-or tick-borne viruses are common in
particular geographical regions.
 Seasonofthe year. Mosquito- and tick-borne diseases tend to be more
common in summer in many areas of the United States.
CLINICAL FEATURES:-
Encephalitis often is preceded by a viral illness such as an upper respiratory
infection, or a gastrointestinal problem, such as diarrhea, nausea, or vomiting. The
following are the most common symptoms of encephalitis. However, each
individual may experience symptoms differently. Symptoms may include:
 Headache
 Sensitivity to light
 Neck stiffness
 Sleepiness or lethargy
 Increased irritability
 Seizures
 Skin rashes
 Difficulty talking and speech changes
 Changes in alertness, confusion, or hallucinations
 Loss of energy
 Loss of appetite
 Unsteady gait
 Nausea and vomiting
 In severe cases, an individual may experience the following:

4.  Loss of muscle power in the arms and legs
 Double vision
 Impairment of speechand/or hearing
 Coma
 The symptoms of encephalitis may resemble other problems or medical
conditions. Always consult your doctorfor a diagnosis.
COMPLICATIONS OF SEVERE ILLNESS:-
Inflammation can injure the brain, possibly resulting in a coma or death.
Other complications ,varying greatly in severity, may persist for months or be
permanent. These complications can include:
Persistent fatigue
Weakness or lack of muscle coordination
Personality changes
Memory problems
Paralysis
Hearing or vision defects
Speech impairments
DIAGNOSIS:-
Diagnostic tests that may be performed to confirm the diagnosis of encephalitis
may include the following:
1- Bloodand urine tests that may be helpful include the following:
 Complete blood count (CBC)
 Serum electrolyte levels
 Serum glucose level
 Blood urea nitrogen (BUN) and creatinine levels
 Urine electrolyte levels
 Urine or serum toxicology screening
A neurological examination generally finds that the patient is confused and
drowsy

5. 2-Magnetic resonanceimaging (MRI). A diagnostic procedurethat uses a
combination of large magnets, radiofrequencies, and a computer to
producedetailed images of organs and structures within the body.
3-Computed tomography scan(also calleda CT or CAT scan). A
diagnostic imaging procedure that uses a combination of X-rays and
computer technology to produce horizontal, or axial, images (often called
slices) of the body. A CT scan shows detailed images of any part of the
body, including the bones, muscles, fat, and organs. CT scans are more
detailed than general X-rays.
4-stooltests
5-Sputum culture. A diagnostic test performed on the material that is
coughed up from the lungs and into the mouth. A sputum culture is often
performed to determine if an infection is present.
6-Electroencephalogram(EEG). A procedurethat records the brain's
continuous, electrical activity by means of electrodes attached to the scalp.
7-Spinal tap (also called a lumbar puncture). A special needle is placed
into the lower back, into the spinal canal. This is the area around the spinal
cord. The pressure in the spinal canal and brain can then be measured. A
small amount of cerebral spinal fluid (CSF)can be removed and sent for
testing to determine if there is an infection or other problems. CSF is the
fluid that bathes the brain and spinal cord.
8-Brain biopsy. A procedureperformed to remove tissue or cells from the
bodyfor examination under a microscope;in rare cases, a biopsy of
affected brain tissue may be removed for diagnosis.
9- Intracranial pressure monitoring (ICP). Measures the pressure
inside the child's skull. If there is a severe brain injury, head surgery, brain
infection, or other problems, the brain may swell. Since the brain is covered by
the skull, there is only a small amount of room for it to swell. This means that,
as the brain swells, the pressure inside the skull goes up. If the pressure gets
significantly higher than normal, it can cause damage to the brain. People
who have hydrocephalus or brain tumors may also have their intracranial
pressure monitored.
Intracranial pressure is measured in two ways. One way is to place a small, hollow
tube (catheter) into the fluid-filled spacein the brain (ventricle). Other times, a
small, hollow device (bolt) is placed through the skull into the spacejust between

6. the skull and the brain. Both devices are inserted by the doctoreither in the
intensive care unit (ICU) or in the operating room. The ICP device is then
attached to a monitor that gives a constantreading of the pressure inside the skull.
If the pressuregoes up, it can be treated right away. While the ICP device is in
place, you will be given medication to stay comfortable. When the swelling has
gone down and there is little chance of more swelling, the device will be removed.
TREATMENT:-
PREVENTION
The bestway to prevent viral encephalitis is to take precautions to avoid exposure
to viruses that can cause the disease.
 Practice goodhygiene. Wash hands frequently and thoroughly with soap and
water, particularly after using the toilet and before and after meals.
 Don't share utensils. Don't share tableware and beverages.
 Teach children goodhabits. Make sure they practice good hygiene and avoid
sharing utensils at home and school.
 Get vaccinations.
 Protectionagainstmosquitoes and ticks
 Dress to protect yourself.
 Apply mosquito repellent.
 Use insecticide
 Avoid mosquitoes.
 Get rid of water sources outside your home.
 Look for outdoor signs of viral disease
Specific treatment for encephalitis will be determined based on:
 Age, overall health, and medical history
 Extent of the condition
 Tolerance for specific medications, procedures, or therapies
 Expectations for the courseof the condition

7.  Opinion or preference
The key to treating encephalitis is early detection and treatment. A personwith
encephalitis requires immediate hospitalization and close monitoring.
The goal of treatment is to reduce the swelling in the head and to prevent other
related complications. Medications to controlthe infection, seizures, fever, or other
conditions may be used.
 Antiviral medicines
 steroid injections
 Treatments to help controlthe immune system
 antibiotics or antifungal medicines
 Painkillers to reduce discomfort or a high temperature
 Medicine to control seizures or fits
 Supportwith breathing, suchas oxygen through a face mask or a breathing
machine (ventilator)