Encephalitis is an inflammation of the brain tissue (parenchyma) and an important cause of morbidity, death, and permanent nerve-related disability in both adults and children.

Globally, 1,444,720 incident cases, 89,900 deaths, related to encephalitis while in India, in a span of 6 years, there have been more than 44,000 cases and nearly 6000 deaths.

Encephalitis can be life-threatening and hence, prompt diagnosis and treatment are vital to predict the course of encephalitis in each individual.

What are the symptoms of Encephalitis?

The symptoms of encephalitis depend on the type of infection. Signs of encephalitis are:

• Fatigue or loss of energy
• High fever
• Severe Headache
• Sensitivity to light and sound
• Stiffness of the neck ranging from Mild-to-moderate
• Drowsiness or loss of consciousness
• Irritability, anxiety, and behavioral or personality changes

Signs of severe encephalitis may include:

• Weakness or trouble moving some parts of your body
• Double vision
• Confusion, trouble speaking, hallucinations (imagining things that don’t exist)
• Coma
• Seizures
• A bulging soft spot (fontanel) in infants

Symptoms in cases of autoimmune encephalitis –

These symptoms may develop more slowly over several weeks, along with a combination of symptoms such as:

• Changes in personality.
• Memory loss.
• Problems understanding what is real and what is not, known as psychosis.
• Seeing or hearing things that aren’t there. These are called hallucinations.
• Seizures.
• Changes in vision.
• Sleep problems.
• Muscle weakness.
• Loss of sensation.
• Problems walking.
• Abnormal movements.
• Bladder and bowel problems.

What are the causes and risk factors of Encephalitis?

In approximately half of patients, the exact cause of encephalitis is not known. However, there are two main types of encephalitis where the cause has been identified:

Infectious encephalitis – When a virus or other agent directly infects the brain. Viruses are the most common cause of encephalitis including some that can be passed by mosquitoes or ticks.; bacteria, fungus or parasites being the rare causes.

Viruses that may cause encephalitis are:

• Herpes viruses, which include HSV (especially HSV-1), chickenpox, cytomegalovirus, and Epstein-Barr virus
• Viruses that are transmitted through bug bites, such as West Nile virus, Dengue virus, and Eastern equine encephalitis virus
• Viruses that cause childhood infections, such as measles, mumps, and Rubella

Autoimmune encephalitis – When the body’s own immune cells mistakenly attack the brain or make antibodies targeting proteins and receptors in the brain.

Risk factors for encephalitis are:

• Age
• Weakened immune system
• Geographical regions where mosquito- or tick-borne viruses are common
• Season of the year where some diseases are more common than in other season.
• Autoimmune disease – People already having one autoimmune condition
• Smoking.

How is Encephalitis diagnosed?

The doctor asks about the symptoms, and its duration. A good medical history is vital and that includes telling the doctor about a person with symptoms coming in contact with mosquitoes or ticks, infected animals, or sick people.

The doctor may do a physical exam and some tests.

• Blood tests
• Urine, stool, or sputum culture tests
• Imaging tests, such as CT scans, MRI scans, and magnetoencephalography (MEG) to see location of seizures in the brain.
• Electroencephalogram (EEG) to look for seizers or specific electrical activity in the brain
• Spinal tap (lumbar puncture) to remove the brain fluid (cerebrospinal fluid) to check for infections in brain or spinal cord
• A neurological exam is conducted to assess how well the nervous system is working
• An intracranial pressure monitoring (ICP) to measure the pressure inside skull
• Rarely, a brain biopsy (small sample brain tissue is removed) in case of worsening symptoms and if treatments do not work.

What are the treatment options for Encephalitis?

Treatment for mild encephalitis:

• Bed rest.
• Plenty of fluids.
• Anti-inflammatory medicines — to relieve headaches and fevers.

In case of complications or serious encephalitis, hospital admission may be required and the blood pressure, heart rate, and breathing may be monitored. Common treatments include:

• Steroids to help reduce swelling in your brain
• Antiviral drugs for people with viral encephalitis
• Antibiotics for people with bacterial encephalitis
• Anticonvulsant therapy for people with seizures
• Immune globulin and plasmapheresis for people with autoimmune encephalitis
• Over-the-counter medicines, such as paracetamol, to help control fever and headaches

Supportive Care may be need for people who are hospitalized with severe encephalitis –

• Breathing assistance, as well as careful monitoring of breathing and heart function.
• Intravenous fluids to ensure proper hydration and levels of essential minerals.
• Anti-inflammatory medicines, such as corticosteroids, to reduce swelling and pressure within the skull.
• Anticonvulsant medicines,to stop or prevent seizures.

Post treatment therapy

In case of complications of encephalitis, additional therapy may be required. These may be:

• Brain rehabilitation to improve cognition and memory.
• Physical therapy to improve strength, flexibility, balance, motor coordination and mobility.
• Occupational therapy to improve everyday skills to help with everyday activities.
• Speech therapy
• Psychotherapy to learn coping strategies and dealing with mood behaviors,etc.

Can Encephalitis be prevented?

Viral encephalitis may be prevented by taking precautions to avoid virus exposures. These precautions are:

• Practicing good hygiene like frequent hand washing, particularly after using the toilet and before and after meals.
• Not sharing utensils, tableware and beverages.
• Teaching children good habits of good hygiene.
• Getting regular vaccinations. 

Protection against mosquitoes and ticks

• Dress to protect yourself by wearing long-sleeved shirts and long pants outside between dusk and dawn when mosquitoes are most active
• Apply mosquito repellent such as DEET to both the skin and clothes.
• Use insecticide that can be sprayed on products on clothing, tents and other outdoor gear.
• Avoid mosquitoes if possible, like avoiding outdoors from dusk till dawn,
• Get rid of water sources outside home such as standing water where mosquitoes may lay their eggs. Common problems include flowerpots or other gardening containers, flat roofs, old tires, and clogged gutters.

Protection for young children

Insect repellents are not recommended for infants younger than 2 months of age. For older infants and children, repellents with 10% to 30% DEET are considered safe.

References:

1. Wang H, Zhao S, Wang S, Zheng Y, Wang S, Chen H, Pang J, Ma J, Yang X, Chen Y. Global magnitude of encephalitis burden and its evolving pattern over the past 30 years. J Infect. 2022 Jun;84(6):777-787.
2. Encephalitis. Mayo Clinic. May 2024. https://www.mayoclinic.org/diseases-conditions/encephalitis/symptoms-causes/syc-20356136
3. Understanding Encephalitis: The Basics. WebMD. May 2024. https://www.webmd.com/a-to-z-guides/understanding-encephalitis-basics