Encephalitis Diagnosis and Treatment

Understanding Encephalitis — Diagnosis and Treatment

Articles On Understanding Encephalitis

Understanding Encephalitis

Understanding Encephalitis — Understanding Encephalitis — Diagnosis and Treatment

How Is Encephalitis Diagnosed?

To diagnose encephalitis, your doctor will consider your symptoms and ask about any recent illnesses and possible exposure to viruses — being near others who are ill or near mosquitoes or ticks, for example.

Your doctor may also order a magnetic resonance imaging (MRI) scan, spinal tap, or an electroencephalogram (EEG).

Blood tests to check for the presence of bacteria or viruses and immune cells produced in response to them can also be helpful.

Rarely, an analysis of a brain tissue sample (biopsy) may be necessary to confirm the diagnosis in cases where symptoms are worsening and treatments aren’t working. It can be very important to identify the type of encephalitis so that appropriate treatment can be given.

What Are the Treatments for Encephalitis?

Because complications from encephalitis can be serious, the condition requires hospitalization. Treatment will depend largely on your age and condition, as well as the form and cause of the disease. If encephalitis is caused by a bacterial infection, it can be treated with intravenousВ antibiotics. Treatment for herpes-related encephalitis includes supportive care, as well as intravenous antiviral therapy with a drug such as acyclovir. Other treatments may be used to lower fever, provide hydration, treat seizures if they develop, and reduce any pressure in the skull.

With proper care, many people recover from encephalitis. Infants and elderly people are at greater risk of sustaining permanent brain damage.


First multiplex test for tick-borne diseases

Promising to revolutionize diagnosis, a single blood test can now accurately detect if someone is infected with Lyme and/or one of seven other tick-borne diseases

A new blood test called the Tick-Borne Disease Serochip (TBD Serochip) promises to revolutionize the diagnosis of tick-borne disease by offering a single test to identify and distinguish between Borrelia burgdorferi, the pathogen responsible for Lyme disease, and seven other tick-borne pathogens. Led by scientists at the Center for Infection and Immunity (CII) at Columbia University’s Mailman School of Public Health, the research team report details on the new test in the journal Nature: Scientific Reports.

The researchers — who also include scientists from the Centers for Disease Control and Prevention, National Institute of Allergy and Infectious Diseases, Roche Sequencing Solutions, Farmingdale State College, and Stony Brook University — sought to improve on existing tests for tick-borne diseases (TBDs), which have limited diagnostic accuracy and cannot test for more than one infection simultaneously. Currently, diagnosis of Lyme disease, the most common TBD, requires two separate tests. This cumbersome approach also relies on subjective criteria for the interpretation of results, and accurately identifies fewer than 40 percent of patients with early disease and results in false positives in 28 percent of the time. The accuracy of the method used to diagnose TBDs Babesia, Anaplasma, Ehrlichia, and Rickettsia varies widely among testing laboratories. And for other tick-borne agents, specific blood tests are not yet available, or in the case of the potentially deadly Powassan virus or Heartland virus, are only performed in specialized laboratories.

«The number of Americans diagnosed with tick-borne disease is steadily increasing as tick populations have expanded geographically,» says Rafal Tokarz, PhD. «Each year, approximately 3 million clinical specimens are tested for TBDs in the U.S. Nonetheless, the true incidence of TBDs is likely greatly underestimated, as patients with presumed TBDs are rarely tested for the full range of tick-borne agents, and only a fraction of positive cases are properly reported,» adds Nischay Mishra, PhD. Co-lead authors Tokarz and Mishra are associate research scientists in the Center for Infection and Immunity.

The TBD Serochip can simultaneously test for the presence of antibodies in blood to more than 170,000 individual protein fragments. Version 1.0 can identify exposure to eight tick-borne pathogens present in the U.S., including Anaplasma phagocytophilum (agent of human granulocytic anaplasmosis), Babesia microti (babesiosis), Borrelia burgdorferi (Lyme disease), Borrelia miyamotoi, Ehrlichia chaffeensis (human monocytic ehrlichiosis), Rickettsia rickettsii (Rocky Mountain spotted fever), Heartland virus and Powassan virus. The researchers also included Long Island tick rhabdovirus, a novel virus they recently discovered in Amblyomma americanum ticks. As new tick-borne infectious agents are discovered, the TBD-Serochip will be modified to target them — a process the researchers say can be done in less than four weeks.

The TBD Serochip is also able to identify whether an individual is infected with more than one tick-borne pathogen. Individual ticks are frequently infected with more than one agent; Ixodes scapularis ticks alone can transmit at least five human pathogens. Evidence of exposure to other tick-borne pathogens in patients with Lyme disease has been well documented. In the new paper, the researchers report finding antibodies to another agent in 26 percent of blood specimens from patients with TBD.

In addition to its utility as a diagnostic platform, the TBD Serochip also provides a powerful research tool for studies of TBDs. The technology can be employed to discriminate individual antibody responses in patients with TBD and thus examine the interplay of TBD agents on disease manifestation and progression. It can also be used to assess the impact of genetic diversity of tick-borne pathogens on the host immune response.

«Diagnosing tick-borne illness is a difficult journey for patients, delaying effecting treatment,» says senior author W. Ian Lipkin, MD, director of CII and John Snow Professor of Epidemiology at Columbia University’s Mailman School of Public Health. «The TBD Serochip promises to make diagnosis far easier, offering a single, accurate test for eight different TBDs. Early detection of infection enables rapid and appropriate treatment.»

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Diagnosis — Encephalitis

The symptoms of encephalitis can have a number of possible causes, so several tests may be needed to diagnose it.

Brain scans

A scan of the brain can help show whether you have encephalitis or another problem such as a stroke, brain tumour or brain aneurysm (a swelling in an artery).

The 2 main types of scan used are:

Lumbar puncture

A lumbar puncture is a procedure to remove some fluid from around the spinal cord (the nerves running up the spine) so it can be checked for signs of encephalitis.

For the procedure:

  • you lie on one side and bring your knees up towards your chin
  • local anaesthetic is used to numb your lower back
  • a needle is inserted into the lower part of your spine and a sample of fluid is removed

The sample will be checked for signs of infection or a problem with your immune system, which are the main causes of encephalitis.

Other tests

Other tests may include:

  • an electroencephalogram (EEG) – where small electrodes are placed on your scalp, which pick up the electrical signals from your brain and show abnormal brain activity
  • tests of your blood, urine or other bodily fluids to check for an infection

Page last reviewed: 3 December 2019
Next review due: 3 December 2022


Tick-borne Encephalitis (TBE)

Tick-borne encephalitis, or TBE, is a human viral infectious disease involving the central nervous system. TBE is caused by the tick-borne encephalitis virus (TBEV), a member of the family Flaviviridae, and was initially isolated in 1937. Three virus sub-types are described: European or Western tick-borne encephalitis virus, Siberian tick-borne encephalitis virus, and Far eastern Tick-borne encephalitis virus (formerly known as Russian Spring Summer encephalitis virus, RSSEV).

The family Flaviviridae includes several tick-borne viruses affecting humans. These viruses are closely related to TBEV and Far-eastern TBE, and include Omsk hemorrhagic fever virus in Siberia, Kyasanur Forest disease virus in India and its close relative, Alkhurma virus in Saudi Arabia. Louping ill virus (United Kingdom) is also a member of this family; it causes disease primarily in sheep and has been reported as the cause of a TBE-like illness in laboratory workers and persons with contact to sick sheep (e.g., veterinarians, butchers). In the USA and Russia, another tick-borne flavivirus, Powassan virus, is responsible of encephalitis in human.

Ticks, specifically hard ticks, act as both the vector and reservoir for TBEV.


How to test for encephalitis without a tick to a person. What tests to pass after a tick bite — a blood test for viruses

Meningitis is an inflammation of the three membranes that cover the brain and spinal cord (the meninges). Encephalitis is an inflammation of the brain. Meningoencephalitis is an inflammation of both the brain and the meninges.

The meninges are layers of tissue that protect the central nervous system, which is comprised of the brain and the spinal cord. The central nervous system is also cushioned and protected by the watery fluid called cerebrospinal fluid (CSF) that surrounds the brain and flows between the meninges, in the spaces within the brain called ventricles, and along the spinal cord.

Meningitis and encephalitis result from infections of the central nervous system caused by a bacterium, virus, fungus, or parasite. These infections can be acute or chronic, and their severity can range from mild and self-limited to fatal. Their associated inflammation and swelling increase pressure on the brain and nerve tissue. This can hinder, or permanently damage, the function of nerves and the body systems that they control. Rarely, certain drugs can cause meningitis, and autoimmune disease can sometimes cause encephalitis.

Meningitis and encephalitis can disrupt the blood-brain barrier that separates the brain from circulating blood and regulates the distribution of substances between the blood and CSF. The blood-brain barrier helps keep large molecules, toxins, and most blood cells away from the brain. With the disruption of this barrier, white and red blood cells, immune system chemicals, toxins, increased amounts of protein, and the microorganism causing the inflammation may be found in the CSF. CSF is a clear, watery liquid that normally flows freely around the brain and spinal cord. With meningitis and encephalitis, the flow of CSF may slow or become obstructed, which can increase CSF pressure, increase pressure on the brain and spinal cord, and decrease blood flow to the brain.

Most cases of meningitis are due to a bacterial or viral infection, but it rarely may also be caused by certain cancers, injuries, parasites, or fungal spores in the environment. Bacterial meningitis can be life-threatening, but there are vaccines to prevent four of the five known types of bacterial meningitis. The infection may originate within the meninges (primary) or spread from an infection site located in another part of the body (secondary).

Viral meningitis, also called aseptic meningitis, is the most common form of meningitis in the United States, according to the Centers for Disease Control and Prevention. It is usually mild to moderate in severity and will usually resolve without treatment (self-limited).

  • Enteroviruses are the most common cause of viral meningitis. Though enteroviruses are very common, they usually cause no symptoms or illness in most cases.

Less common causes include:

Bacterial meningitis is generally considered a medical emergency. Acute cases can arise suddenly, with symptoms worsening within hours to a couple of days. Rapid identification and treatment is crucial. Untreated bacterial meningitis is usually fatal. While this condition can be caused by many different types (species) of bacteria, the most common causes are:

  • Streptococcus pneumoniae – called pneumococcal meningitis; it is currently the most common form of bacterial meningitis in the U.S. It can also cause pneumonia, blood infections (septicemia), and ear and sinus infections. Infants under 2 years old, people with compromised immune systems, and the elderly are at greatest risk for it.
  • Neisseria meningitidis – called meningococcal meningitis; it is highly contagious; people who are at risk include college students, infants, children younger than 1 year old, international travelers, and people with weakened immune systems.
  • Haemophilus influenzae type b – once the most common cause of bacterial meningitis, its incidence has decreased in the U.S. because of widespread vaccination of children.
  • Other causes include Listeria monocytogenes as well as Group B streptococcus and Escherichia coli, which may cause meningitis in a newborn when the mother passes the infection to her baby during delivery. Pregnant women are screened for Group B strep late in their pregnancy to determine whether there is risk of passing the infection to their babies.
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Chronic meningitis is an infection that lasts for more than 4 weeks. It may be caused by microbes such as Mycobacterium tuberculosis, which causes tuberculosis, by Treponema pallidum, which causes syphilis, and by fungi.

Fungal meningitis, though rare, is most commonly seen in immune-compromised patients, such as those with AIDS, but may affect anyone.

  • The most common cause is Cryptococcus neoformans (cryptococcal meningitis), thought to be contracted through inhaling dirt contaminated with bird droppings.

Other causes include:

Fungal meningitis is not contagious; it is not spread from person-to-person but occurs when an individual with a weakened immune system inhales spores from the environment. (For more, read the article on Fungal Infections.)

Parasitic meningitis is rare and can be lethal. One example is an infection caused by the free-living amoeba, Naegleria fowleri, a single-cell parasite, which can be found in warm water lakes and rivers. Infection occurs when the parasite enters the respiratory system through the nose of a person swimming in contaminated water. Another example is infection caused by the Schistosomaparasite. This type of infection does not occur in the U.S. but is common in other areas of the world such as Africa, South America, and South China.

Encephalitis is an acute infection of the brain characterized by fever, headache, and an altered state of consciousness, with or without seizures. Most cases of encephalitis are caused by viruses. They may also be limited to a single location (focal) or diffuse throughout the brain (generalized). Each year there are several thousand cases reported but, according to the National Institute of Neurological Disorders and Stroke, there are probably many more cases with minimal to mild symptoms that occur but are not documented.

Viral encephalitis may be caused by a variety of viruses including:

  • Herpes simplex virus
  • Enteroviruses
  • The rabies virus (from an animal bite)
  • Arboviruses – those spread primarily by infected mosquitoes but also by a few ticks

Most people who are infected have mild to moderate symptoms. Only a very small percentage of people develop encephalitis.

In the United States, West Nile virus is the most common cause of arbovirus encephalitis. Other more rare U.S. arboviruses are distributed geographically. Throughout the world, different types of arbovirus-related encephalitis may predominate. Types of encephalitis caused by arboviruses include:

  • West Nile encephalitis – about one in 5 people infected with West Nile virus will develop fever with other symptoms and less than 1% will develop severe illness, according to the Centers for Disease Control and Prevention (CDC).
  • Western equine encephalitis – per the CDC, about 3% of those affected die; illness is more severe in infants than adults.
  • Eastern equine encephalitis – though this is a rare illness with only a few cases in the U.S. each year, it tends to be one of the most severe; the CDC estimates that about a third of those with the infection will die and many survivors will suffer brain damage.
  • LaCrosse encephalitis – found in the upper Midwest, mid-Atlantic, and southeastern states; most severe cases occur in children less than 16 years of age, according to the CDC.
  • St. Louis encephalitis – a rare infection, most cases occur in eastern and central states in the U.S.; illness is most severe in the elderly.

Other arboviruses that may be seen in other parts of the world include:

  • Japanese encephalitis – found naturally (endemic) in Asia and is associated with rural farming areas; a vaccine to prevent infection is available.
  • Venezuelan equine encephalitis – very rare in the U.S.; has killed thousands of people in South American epidemics.

Viral encephalitis may also be seen as a secondary condition that occurs a few weeks after a viral illness.

Bacterial, fungal, and parasitic encephalitis are very rare. Bacterial meningoencephalitis may develop from the bacteria that cause meningitis. Tick-transmitted Lyme disease may cause bacterial encephalitis. Toxoplasma gondii, a parasite associated with cats, can cause parasitic encephalitis in some people with weakened immune systems.

Meningitis and encephalitis may start with flu-like symptoms and intensify over a few hours to a few days. Characteristic signs and symptoms of these two conditions may overlap and can include:

  • Fever
  • Severe persistent headache
  • A stiff neck
  • Sensitivity to light
  • Mental changes
  • Lethargy

Other symptoms may include confusion, nausea, vomiting, a red or purple rash, and seizures. An elderly person may be lethargic and show few other signs. People with weakened immune systems may have atypical symptoms. Infants may be irritable and cry when they are held, vomit, have body stiffness, have seizures, refuse food, and have bulging fontanels (the soft spots on the top of the head).

Encephalitis symptoms may also include neurological problems such as difficulty with hearing or speech, loss of sensation, partial paralysis, seizures, hallucinations, muscle weakness, changes in personality, and coma.

Complications and Prognosis

The outcome of those with meningitis and encephalitis depends on the specific cause of the condition, the severity, the person’s health and immune status, and how quickly the condition is identified and treated. Those with mild cases may recover fully within a few weeks or may have persistent or permanent complications.

As many as 15-25% of newborns and 15% of other patients with bacterial meningitis die, even when treated appropriately and rapidly. Up to 15-25% of those who survive may have neurological complications (sequelae), including accumulation of fluid within the brain (hydrocephalus), deafness, blindness, periodic seizures, and/or some degree of impaired thinking processes. These complications may occur at any age, but newborns are at the highest risk.

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To investigate possible meningitis or encephalitis, healthcare practitioners start with a physical examination and a medical history. This examination may occur in the emergency room as symptoms may suddenly appear and rapidly worsen over several hours to a couple of days.

The healthcare practitioner will ask about recent illnesses, exposure to animals, mosquitoes, or ticks, contact with other people who have become ill, recent travel – especially outside of the United States, and recent activities. The healthcare practitioner will note the presence or absence of signs and symptoms frequently associated with meningitis and encephalitis. Neurological examinations may be performed to assess the status of the patient’s nervous system, sensory and motor function, coordination, vision, hearing, strength, and mental status.

Laboratory Tests
Laboratory tests are performed to detect, identify, evaluate, and monitor meningitis and encephalitis. These tests are performed in order to:

  • Distinguish these infections from other conditions with similar symptoms
  • Determine the cause, whether bacteria, viruses, fungi, or parasites, as rapidly as possible to start and guide treatment
  • Evaluate the affected person’s general state of health, immune system status, current signs and symptoms, and current complications to guide symptom relief and to minimize inflammation and neurological or brain damage
  • Where possible, determine the infection’s source; this is especially important when the microbe causing the infection may be spread to others and may be a public health concern.

Depending on the suspected cause, samples may be sent to local or state public health laboratories for testing.

Tests include:
Cerebrospinal fluid (CSF) analysis. This is a primary diagnostic tool for encephalitis and meningitis. CSF analysis is a group of common tests, and a wide variety of other tests, that can be ordered and performed on a sample of CSF. It is collected using a procedure called a lumbar puncture or spinal tap.

Initial CSF tests—The initial basic set of CSF tests that are often performed with suspected infections of the central nervous system include:

  • Physical characteristics: normal CSF appears clear and colorless. The appearance of the sample of CSF is usually compared to a sample of water. In infections, the initial pressure of CSF during collection may be increased and the sample may appear cloudy due to the presence of white blood cells (WBCs) or microorganisms.
  • CSF protein: only a small amount is normally present in CSF because proteins are large molecules and do not cross the blood/brain barrier easily. Increases in protein are commonly seen with meningitis, brain abscess, and neurosyphilis.
  • CSF glucose: normal is about 2/3 the concentration of blood glucose. Glucose levels may decrease when cells that are not normally present use up (metabolize) the glucose. These may include bacteria or cells present due to inflammation (WBCs).
  • CSF total cell counts: WBCs may be increased with central nervous system infections.
  • CSF WBC differential: small numbers of lymphocytes, monocytes (and in neonates, neutrophils) are normal in a sample of CSF. There may be:
    • An increase in neutrophils with a bacterial infection
    • An increase in lymphocytes with a viral infection
    • Sometimes an increase in eosinophils with a parasitic infection
  • CSF Gram stain for direct observation of microbes
  • CSF culture and sensitivity for bacteria, fungi, and viruses

Additional or follow-up CSF tests—If any of the initial tests are abnormal, then additional infectious testing may be ordered. This may include one or more of the following:

  • Detection of viruses by molecular tests (polymerase chain reactions, PCR) – detection of viral genetic material (DNA, RNA) such as West Nile virus, herpes, and enteroviruses
  • CSF Cryptococcal antigen – to detect a specific fungal infection
  • Other CSF antigen tests – depending on which organism(s) are suspected
  • Specific CSF antibody tests – depending on which organism(s) are suspected

Less commonly ordered CSF infectious diseases tests include:

  • CSF AFB smear and culture (when tuberculosis is suspected) – positive with tuberculosis and with other mycobacteria
  • CSF Molecular tests to detect Mycobacteria tuberculosis
  • CSF syphilis testing (VDRL) – positive with syphilis that has infected the brain (neurosyphilis); negative does not rule out condition

Several other types of CSF testing may occasionally be ordered to help distinguish between viral and bacterial meningitis:

  • CSF lactic acid – often used to distinguish between viral and bacterial meningitis; the level will usually be increased with bacterial and fungal meningitis while it will remain normal or only slightly elevated with viral meningitis.
  • CSF lactate dehydrogenase (LD) – used to differentiate between bacterial and viral meningitis
  • CSF C-reactive protein (CRP) is an acute phase reactant and is elevated with inflammation; it is markedly increased with bacterial meningitis. Since it is very sensitive even with early bacterial meningitis, it is often used to distinguish between bacterial and viral meningitis.

Laboratory tests on samples other than CSF—may be ordered along with or following CSF testing and may include:

  • Blood glucose, protein, CBC (complete blood count) – to evaluate and to compare with CSF levels
  • Procalcitonin – growing evidence suggests that measuring blood levels of procalcitonin is useful in distinguishing bacterial from viral meningitis; a high blood level is a strong indication of bacterial meningitis.
  • Tests for antibodies in blood for a variety of viruses, such as arboviruses, in particular West Nile virus, if there is a four-fold rise in the titer of the antibody between two samples collected about a month apart, then it indicates a recent infection by that microorganism.
  • Molecular tests that directly detect viruses in blood
  • Blood cultures may be ordered to detect and identify bacteria in the blood.
  • Cultures of other parts of the body may be performed to detect the source of the infection that led to meningitis or encephalitis.
  • CMP (comprehensive metabolic panel) – tests that evaluate organ function

Non-Laboratory Tests
Imaging tests may be performed to look for signs of brain inflammation or abnormalities but may be unremarkable with encephalitis. Brain damage, tumors, bleeding, and abscesses may be detected. Tests may include:

  • CT (computed tomography)
  • MRI (magnetic resonance imaging)
  • Ultrasound
  • EEG (electroencephalography) – to detect abnormal brain waves


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