National Institute of Neurological Disorders and Stroke

What is encephalitis?

Encephalitis is inflammation of the brain. Myelitis refers to inflammation of the spinal cord. When both the brain and the spinal cord are involved, the condition is called encephalomyelitis.

Infections and other disorders affecting the brain and spinal cord can activate the immune system, which leads to inflammation. This inflammation can produce a wide range of symptoms and, in extreme cases, cause brain damage, stroke, or even death.

Individuals with encephalitis often show mild flu-like symptoms. In more severe cases, people may experience:

• Problems with speech or hearing
• Double vision
• Hallucinations
• Personality changes
• Loss of consciousness
• Loss of sensation in some parts of the body

• Muscle weakness
• Partial paralysis in the arms and legs
• Impaired judgment
• Seizures
• Memory loss

Important signs of encephalitis to watch for in an infant include fever, lethargy, not waking for feedings, vomiting, body stiffness, unexplained/unusual irritability, and a full or bulging fontanel (the soft spot on the top of the head).

Who is more likely to get encephalitis?

Anyone—from infants to older adults—can get encephalitis. People with weakened immune systems, including those persons with HIV or those taking immunosuppressant drugs, are at increased risk.

Some forms of encephalitis are contagious and can be spread through contact with:

• Saliva
• Nasal discharge
• Feces
• Respiratory and throat secretions (often spread through kissing, coughing, or sharing drinking glasses, eating utensils, or such personal items as toothbrushes, lipstick, or cigarettes)

For example, people sharing a household, at a day care center, or in a classroom with an infected person can become infected. College students living in dormitories—in particular, college freshmen—have a higher risk of contracting meningococcal meningitis than college students overall.

Because the disease can occur suddenly and progress rapidly, anyone who is suspected of having encephalitis should immediately contact a doctor or go to the hospital.

Causes of encephalitis

Infectious causes of encephalitis include bacteria, viruses, fungi, and parasites. For some individuals, environmental exposure (such as a parasite), recent travel, or an immunocompromised state (such as HIV, diabetes, steroids, chemotherapy treatment) are important risk factors. There are also non-infectious causes such as autoimmune/rheumatological diseases and certain medications.

Up to 60 percent of cases of encephalitis remain undiagnosed. Several thousand cases are reported each year, but many more may occur since the symptoms may be mild to non-existent in most individuals.

Most diagnosed cases in the U.S. are caused by herpes simplex virus types 1 and 2, arboviruses (such as the West Nile Virus), which are transmitted from infected animals to humans through the bite of an infected tick, mosquito, or other blood-sucking insect, or enteroviruses. Lyme disease, a bacterial infection spread by tick bite, occasionally causes meningitis, and very rarely encephalitis. Rabies virus, which is transmitted by bites of rabid animals, is an extremely rare cause of human encephalitis.

Herpes simplex encephalitis (HSE) is responsible for about 10 percent of all encephalitis cases, with a frequency of about two cases per million people per year. More than half of untreated cases are fatal. About 30 percent of cases result from the initial infection with the herpes simplex virus; the majority of cases are caused by reactivation of an earlier infection. Most people acquire herpes simplex virus type 1 (the cause of cold sores or fever blisters) in childhood.

HSE due to herpes simplex virus type 1 can affect any age group but is most often seen in persons under age 20 or over age 40. This rapidly progressing disease is the single most important cause of fatal sporadic encephalitis in the country. Symptoms can include headache and fever for up to five days, followed by personality and behavioral changes, seizures, hallucinations, and altered levels of consciousness.  Brain damage in adults and in children beyond the first month of life is usually seen in the frontal lobes (leading to behavioral and personality changes) and temporal lobes (leading to memory and speech problems) and can be severe. 

Type 2 virus (genital herpes) is most often transmitted through sexual contact. Many people do not know they are infected and may not have active genital lesions. An infected mother can transmit the disease to her child at birth, through contact with genital secretions. In newborns, symptoms such as lethargy, irritability, tremors, seizures, and poor feeding generally develop between four and 11 days after delivery.

Four common forms of mosquito-transmitted viral encephalitis are seen in the United States:

1. Equine encephalitis affects horses and humans  
   • Eastern equine encephalitis also infects birds that live in freshwater swamps of the eastern U.S. seaboard and along the Gulf Coast. In humans, symptoms are seen within four days or up to two weeks following transmission and include sudden fever, general flu-like muscle pains, and headache of increasing severity, followed by coma and death in severe cases.  About half of infected individuals die from the disorder. Fewer than 10 human cases are seen annually in the United States. 
   • Western equine encephalitis is seen in farming areas in the western and central plains states. Symptoms begin within five and up to 10 days following infection. Children, particularly those under 12 months of age, are affected more severely than adults and may have permanent neurologic damage. Death occurs in about three percent of cases. 
   • Venezuelan equine encephalitis is very rare in the U.S. Children are at greatest risk of developing severe complications, while adults generally develop flu-like symptoms. Epidemics in Central and South America have killed thousands of people and left others with permanent, severe neurologic damage.
2. LaCrosse encephalitis occurs in the upper midwestern states (Illinois, Wisconsin, Indiana, Ohio, Minnesota, and Iowa) but has been reported in the southeastern and mid-Atlantic regions of the country.  Most cases are seen in children under the age of 16. Symptoms such as vomiting, headache, fever, and lethargy appear up to 10 days following infection. Severe complications include seizures, coma, and permanent neurologic damage. About 100 cases of LaCrosse encephalitis are reported each year.
3. St. Louis encephalitis is most prevalent in temperate regions of the U.S. but can occur throughout most of the country. The disease is generally milder in children than in adults, with elderly adults at highest risk of severe disease or death. Symptoms typically appear within seven days and up to 10 following infection and include headache and fever. In more severe cases, confusion and disorientation, tremors, convulsions (especially in the very young), and coma may occur.
4. West Nile encephalitis is usually transmitted by a bite from an infected mosquito but can also occur after transplantation of an infected organ or transfusions of infected blood or blood products. Symptoms are flu-like and include fever, headache, and joint pain. Some individuals may develop a skin rash and swollen lymph glands, while others may not show any symptoms. At highest risk are older adults and people with weakened immune systems.

Outside the U.S., Japanese encephalitis is one of the most common causes of encephalitis worldwide. It is widespread in Asia and transmitted by a mosquito. A vaccine is available so travelers to at-risk areas should discuss this with their healthcare provider.

Powassan encephalitis is rare but is the only well-documented tick-borne arbovirus in the U.S. and Canada. Symptoms are noticed seven to 10 days following the bite (most people do not notice tick bites) and may include headache, fever, nausea, confusion, partial paralysis, coma, and seizures.

It is also possible to develop encephalitis that has non-infectious or autoimmune causes. Some cases of encephalitis are caused by an autoimmune disorder that may in some instances be triggered by an infection (“post infectious”) or by a cancer—even one that is microscopic and cannot be found (so-called paraneoplastic neurological syndromes).  NMDA-Receptor encephalitis is a type of autoantibody-mediated encephalitis and is being increasingly recognized; it was the most documented form of non-bacterial meningitis reported in the long-term study and follow-up of participants in the California Encephalitis project. Treatment involves immunosuppression and/or tumor removal if such a cause is found.

How is encephalitis diagnosed and treated?

Diagnosing encephalitis

Following a physical exam and medical history to review activities of the past several days or weeks (such as recent exposure to insects, ticks or animals, any contact with ill persons, or recent travel; preexisting medical conditions and medications), the doctor may order various diagnostic tests to confirm the presence of infection or inflammation. Early diagnosis is vital, as symptoms can appear suddenly and escalate to brain damage, hearing and/or speech loss, blindness, or even death.

Diagnostic tests include:

• A neurological examination involves a series of physical examination tests designed to assess motor and sensory function, nerve function, hearing and speech, vision, coordination and balance, mental status, and changes in mood or behavior.
• Laboratory screening of blood, urine, and body secretions can help detect and identify brain and/or spinal cord infection and determine the presence of antibodies and foreign proteins. Such tests can also rule out metabolic conditions that may have similar symptoms.
• Analysis of the cerebrospinal fluid that surrounds and protects the brain and spinal cord can detect infections in the brain and/or spinal cord, acute and chronic inflammation, and other diseases. A small amount of cerebrospinal fluid is removed by a special needle that is inserted into the lower back and the fluid is tested to detect the presence of bacteria, blood, and viruses. The testing can also measure glucose levels (a low glucose level can be seen in bacterial or fungal meningitis) and white blood cells (elevated white blood cell counts are a sign of inflammation), as well as protein and antibody levels.

Brain imaging can reveal signs of brain inflammation, internal bleeding or hemorrhage, or other brain abnormalities. Two imaging procedures are routinely used to diagnose meningitis.

1. Computed tomography (CT)
2. Magnetic resonance imaging (MRI)

Additionally, electroencephalography (EEG) can identify abnormal brain waves by monitoring electrical activity in the brain.

Treating encephalitis

People who are suspected of having encephalitis should receive immediate, aggressive medical treatment. The disease can progress quickly and has the potential to cause severe, irreversible neurological damage.

Antiviral drugs used to treat viral encephalitis include acyclovir and ganciclovir. For most encephalitis-causing viruses, no specific treatment is available.

Autoimmune causes of encephalitis are treated with additional immunosuppressant drugs and screening for underlying tumors when appropriate. Acute disseminated encephalomyelitis, a non-infectious inflammatory brain disease mostly seen in children, is treated with steroids.

Anticonvulsants may be prescribed to stop or prevent seizures.  Corticosteroids can reduce brain swelling. Affected individuals with breathing difficulties may require artificial respiration.

Once the acute illness is under control, comprehensive rehabilitation should include cognitive rehabilitation and physical, speech, and occupational therapy.

Prevention

People should avoid sharing food, utensils, glasses, and other objects with someone who may be exposed to or have the infection. People should wash their hands often with soap and rinse under running water.

To lessen the risk of being bitten by an infected mosquito or other arthropod, people should limit outdoor activities at night, wear long-sleeved clothing when outdoors, use insect repellents that are most effective for that particular region of the country, and rid lawn and outdoor areas of free-standing pools of water (where mosquitoes like to breed). Repellants should not be overapplied, particularly on young children and especially infants, as chemicals like DEET may be absorbed through the skin.

The outlook for individuals with encephalitis generally depends on the particular infectious agent involved, the severity of the illness, and how quickly treatment is given. In most cases, people with very mild encephalitis can make a full recovery, although the process may be slow.

In more serious cases, the disease can cause hearing and/or speech loss, blindness, permanent brain and nerve damage, behavioral changes, cognitive disabilities, lack of muscle control, seizures, and memory loss. These individuals may need long-term therapy, medication, and supportive care. 

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Learn About Clinical Trials

Clinical trials are studies that allow us to learn more about disorders and improve care. They can help connect patients with new and upcoming treatment options.

How can I or my loved one help improve care for people with encephalitis?

Consider participating in a clinical trial so clinicians and scientists can learn more about encephalitis and related disorders.  Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with encephalitis at Clinicaltrials.gov.

Where can I find more information about encephalitis?

Information may be available from the following resources:

Centers for Disease Control and Prevention (CDC)
Phone: 800-232-4636

HHV-6 Foundation
Phone: 888-530-6726

MedlinePlus

National Institute of Allergy and Infectious Disease (NIAID)
Phone: 301-496-5717 or 866-284-4107

Learn about related topics

• Meningitis

Encephalitis – NHS

Encephalitis is an uncommon but serious condition in which the brain becomes inflamed (swollen).

It can be life threatening and requires urgent treatment in hospital.

Anyone can be affected, but the very young and very old are most at risk.

Symptoms of encephalitis

Encephalitis usually starts off with flu-like symptoms, such as a high temperature and headache.

More serious symptoms come on over hours, days or weeks, including:

• confusion or disorientation
• seizures or fits
• changes in personality and behaviour
• difficulty speaking
• weakness or loss of movement in some parts of the body
• loss of consciousness

Dial 999 for an ambulance immediately if you or someone else has these serious symptoms.

Causes of encephalitis

It’s not always clear what causes encephalitis, but it can be caused by:

• viral infections – very rarely, encephalitis may be caused by the common viruses that causes cold sores (herpes simplex) or chickenpox (herpes varicella) spreading to the brain
• a problem with the immune system, the body’s defence against infection – sometimes something goes wrong with the immune system and it mistakenly attacks the brain, causing it to become inflamed
• bacterial or fungal infections – these are much rarer causes of encephalitis than viral infections

Some types of encephalitis are spread by mosquitoes (such as Japanese encephalitis), ticks (such as tick-borne encephalitis) and mammals (such as rabies).

You cannot catch encephalitis from someone else.

Treatments for encephalitis

Encephalitis needs to be treated in a hospital. The earlier treatment is started, the more successful it’s likely to be.

Treatment depends on the underlying cause, but may include:

• antiviral medicines
• steroid injections
• treatments to help control the immune system
• antibiotics or antifungal medicines
• painkillers to reduce discomfort or a high temperature
• medicine to control seizures or fits
• support with breathing, such as oxygen through a face mask or a breathing machine (ventilator)

How long someone with encephalitis needs to stay in hospital can range from a few days to several weeks or even months.

Recovering from encephalitis

Some people eventually make a full recovery from encephalitis, although this can be a long and frustrating process.

Many people never make a full recovery and are left with long-term problems caused by damage to their brain.

Common complications include:

• memory loss (amnesia)
• frequent seizures or fits
• personality and behavioural changes
• problems with attention, concentration, planning and problem solving
• persistent tiredness

These problems can have a significant impact on the life of the affected person, as well as their family and friends.

But help and support is available.

Preventing encephalitis

It’s not always possible to prevent encephalitis, but some of the infections that cause it can be prevented with vaccinations.

These include the:

• measles, mumps and rubella (MMR) vaccine – a routine vaccination offered to all children in England
• Japanese encephalitis vaccine – recommended for travellers to at-risk areas, such as parts of Asia
• tick-borne encephalitis vaccine – recommended for travellers to certain parts of Europe (but not the UK) and Asia
• rabies vaccination – recommended for travellers to at-risk where access to medical care is likely to be limited. Find out about rabies risks in terrestrial animals by country on GOV.UK.

Speak to a GP surgery if you’re not sure whether your vaccinations are up to date, or you’re planning to travel abroad and do not know if you need any vaccinations.

Page last reviewed: 15 May 2023
Next review due: 15 May 2026

Treatment of inflammation of the brain or spinal cord (meningitis, encephalitis, myelitis)

Treatment of inflammation of the brain or spinal cord (meningitis, encephalitis, myelitis)

Myelitis is a general term for diseases and any inflammatory processes affecting the human spinal cord. Encephalitis is a group of diseases characterized by inflammation of the brain. In turn, meningitis is an infectious disease that affects the membranes of both the spinal cord and the brain.

Causes of inflammation

Encephalitis is caused by neurotropic viruses. The disease can also occur due to complications of rubella, smallpox and measles, and infection can also occur through ticks or mosquitoes. Meningitis is caused mainly by three types of bacteria – pneumococci, meningococci and Haemophilus influenzae. Thus, the cause of inflammation of the spinal cord or brain one way or another are infections of a viral, fungal or bacterial nature, or parasites.

Symptoms

The clinical picture is determined by the general extent and severity of the lesion. In most cases, patients experience the following symptoms:

• headache
• rise in body temperature
• nausea
• sensitivity to light
• general weakness
• in extreme manifestations, paralysis, epileptic seizures, impaired consciousness, etc. are possible.

Diagnosis

To diagnose and start treatment of inflammation of the spinal cord or brain, it is necessary to be examined by a neurologist. In addition to the examination, additional studies are carried out, including:

• computed tomography of the spinal cord and/or brain
• magnetic resonance imaging
• lumbar puncture for cerebrospinal fluid analysis, etc.

Treatment of inflammation of the brain or spinal cord

In such diseases, the doctors of the Viva clinic prescribe mainly drug therapy. As an additional treatment for inflammation of the brain and spinal cord, physiotherapy exercises, physiotherapy, and massage sessions are indicated.

Drug therapy involves taking antibiotics, vitamins, antiseptics, and other drugs. In addition, to ensure the effectiveness of the treatment of inflammation of the spinal cord and brain, an important role is played by:

• proper nutrition
• bed rest
• competent rehabilitation after recovery

Neurologists

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Inflammation of the meninges – diagnosis and treatment at 100med

What is this disease

Meningitis is often referred to as inflammation of the meninges. In the event of its occurrence, the protective layers of the spinal cord and brain become inflamed. This occurs under the influence of simple microorganisms, bacteria, fungal or viral infections. In some cases, the cause of inflammation can be medication or an injury.

Symptoms

Symptoms of inflammation of the meninges:

• increase in body temperature;

• the occurrence of hearing problems;

• significant headaches;

• nausea;

• loss of consciousness;

• vomit;

• the appearance of a rash on the skin;

• neck stiffness;

• drowsiness;

• convulsions;

• mental problems, including apathy, hallucinations, anxiety, agitation and other types.

Causes

Causes of inflammation of the meninges:

• influence of the simplest microorganisms;

• the presence of fungal infections;

• bacterial types of infections;

• viral diseases;

• a combination of several types of pathogens.

Diagnosis

Diagnosis of inflammation of the meninges is carried out as follows:

• general, PCR and biochemical blood tests;

• neurological examination;

• electroencephalography;

• puncture of the cerebrospinal type;

• CT study.

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Our expert’s opinion

Meningitis occurs in acute, fulminant and chronic forms, so only with the right approach can a correct and timely diagnosis be made. Such a complex disease requires complex treatment and high professionalism of medical personnel.

Treatment

Therapy of inflammation of the meninges is carried out in the complex:

• the use of antiviral agents;

• the appointment of antipyretics;

• the use of painkillers;

• antifungal treatment;

• antibacterial therapy.

Also during the treatment of meningitis, it is important to maintain the body’s water balance and adhere to the diet recommended by the specialist.

Prevention

Prevention and treatment of inflammation of the meninges includes vaccination recommended for children, patients with immunodeficiency and persons in contact with carriers of the disease. Also, to prevent illness, it is important to maintain a healthy lifestyle, regularly visit the fresh air, exercise, temper and avoid sources of infection. A balanced diet and the use of vitamin and mineral complexes can be a significant step in the prevention of inflammation of the meninges.