Patients suffering from encephalitis may either have no symptoms or have mild flu-like symptoms like headache, fever, nausea, vomiting, pain in muscles or joints and fatigue or weakness. Other classical signs and symptoms of encephalitis are behavioral and personality changes with low level of consciousness, confusion, agitation or hallucinations, lethargy, seizures, neck pain and stiffness, photophobia, loss of sensation or paralysis in certain parts of the face or body, difficulty in speech and hearing, notion of foul smells like burnt meat or rotten eggs. In infants and young children, the manifestations might also consist of irritability, uncontrollable crying, poor feeding or not waking up for feeding, stiffening of the body, nausea and vomiting, bulging in the fontanels in the infants.

• Fever

  Over-the-counter medications may be used for fever and headache. Individuals with encephalitis or bacterial meningitis are usually hospitalized for treatment. [web.archive.org]

  The diagnosis of dengue fever was confirmed by dengue serology (IgM) and (NS1) antigen assay. MRI brain was suggestive of encephalitis. [ncbi.nlm.nih.gov]

  ‘Famous members of this family cause dengue fever, yellow fever and Japanese encephalitis.’ ‘Rarely, flu can develop into a high fever, acute bronchitis, encephalitis and pneumonia.’ [en.oxforddictionaries.com]

  Symptoms in mild cases of encephalitis usually include: fever headache poor appetite loss of energy a general sick feeling Serious cases of encephalitis can cause: a high fever severe headache nausea and vomiting stiff neck confusion personality changes [kidshealth.org]

• Fatigue

  Symptoms include headache, fever, confusion, drowsiness, and fatigue. More advanced and serious symptoms include seizures or convulsions, tremors, hallucinations, and memory problems . [commons.wikimedia.org]

  Other interesting and important findings are that patients reported more fatigue, and that patients with fatigue also reported a poorer QoL, while poorer cognitive outcome did not affect QoL. [n.neurology.org]

  Are you sad, bored, fatigued, irritable, unable to concentrate, pessimistic? If you've been feeling this way for at least 2 weeks, you may have clinical depression. Learn what can help. Dementia is not something that happens only to older people. [web.archive.org]

  Headache, muscle pain and fatigue can also occur. Top of Page I think I got sick from the vaccine, what should I do? Consult with your healthcare provider. [cdc.gov]

  Symptoms include headache, fever, confusion, drowsiness, and fatigue. More advanced and serious symptoms include seizures or convulsions, tremors, hallucinations, and memory problems. [hannibal.wikia.com]

• Unconsciousness

  Within a few days the patient gets severe symptoms like seizures, unconsciousness, hemiplegia, visual disturbances and aphasia. This leads to rapid referral from the GP to the emergency room. [braininjury-explanation.com]

  Their functions are critical for judgement, perception of reality, human interaction, the formation and retrieval of memory, and the control of unconscious activities (such as breathing, swallowing, etc), also known as autonomic functions. [antinmdafoundation.org]

  From this point on, I only know what I’ve been told, as I was totally unconscious. A doctor announced that I needed to be put on life support to survive, and with this news, my whole family’s hearts were broken. [medicalnewstoday.com]

  Eventually you can become unconscious. You may also start to have seizures (fits). Symptoms can develop quite quickly over a few hours or sometimes they can develop over a few days. [patient.info]

• Chronic Fatigue Syndrome

  ‘The first concern is to rule out treatable forms of dementia such as encephalitis or chronic meningitis.’ ‘This is still the case with conditions such as chronic fatigue syndrome and myalgic encephalitis.’ [en.oxforddictionaries.com]

  Although the exact cause of fibromyalgia is unknown, what is known is that there is a lot of overlap between fibromyalgia and rheumatoid arthritis, chronic fatigue syndrome and systemic lupus erythematosus. [news-medical.net]

  […] and management of myalgic encephalomyelitis/chronic fatigue syndrome following suspected West Nile virus infection Nicole L. [dx.doi.org]

• Weight Gain

  Patients may also exhibit signs and symptoms such as oliguria, weight gain, hyponatremia, and hypo-osmolality. [journals.lww.com]

• Nausea

  Symptoms of meningitis, which may appear suddenly, often include high fever, severe and persistent headache, stiff neck, nausea, sensitivity to bright light, and vomiting. [web.archive.org]

  Symptoms of meningitis, which may appear suddenly, often include: high fever, severe and persistent headache, stiff neck, nausea, sensitivity to bright light, vomiting, and changes in behavior such as confusion, sleepiness, and difficulty waking up. [ninds.nih.gov]

  Some of the most common symptoms of encephalitis may include: fever headache sensitivity to light neck stiffness skin rashes nausea/vomiting loss of energy/appetite changes in alertness (sleepiness) confusion or hallucinations difficulty talking problems [childrenshospital.org]

  Nausea and vomiting. Confusion and changes in mental state, becoming drowsy. Fits. In rare cases, convulsion or paralysis of the arms and legs. Photophobia (dislike of bright light). Hallucinations, changes in personality and behaviour. [netdoctor.co.uk]

• Photophobia

  Encephalitis Symptom Photophobia Sensitivity to light is the inability to tolerate light, medically known as photophobia. [medicinenet.com]

  […] develop within hours or days, which may include: changes in mental state, such as confusion, drowsiness or disorientation seizures (fits) changes in personality and behaviour loss of consciousness Other symptoms can include: sensitivity to bright lights (photophobia [web.archive.org]

  Symptoms The patient typically has a fever, headache, and photophobia (excessive sensitivity to light). There may also be general weakness and seizures. [medicalnewstoday.com]

  Symptoms Symptoms may include: Sudden fever Headache Vomiting Weakness Photophobia (abnormal sensitivity to light) Mental changes (such as confusion or irritability) Drowsiness Difficulty walking Loss of balance Severe complications can include loss of [www1.nyc.gov]

• Pupillary Abnormality

  The patient showed pupillary abnormalities suggestive of a diagnosis of neurosyphilis, and the diagnosis was supported by the results of a serum Treponema pallidum hemagglutination assay (TPHA) and cerebrospinal fluid examination. [jstage.jst.go.jp]

• Delusion

  Rarely (<5% of cases), psychiatric symptoms (hallucinations, mood disturbances, delusions) may be the only symptom of anti-NMDA receptor encephalitis. Many people complain of flu-like symptoms around the time that their disease begins. [antinmdafoundation.org]

• Seizure

  We present a patient with LGI1 encephalitis and "faciobrachial dystonic seizures-plus", which began as classic faciobrachial dystonic seizures and progressed to focal seizures with impaired awareness, dacrystic/gelastic-like outbursts, ictal speech, manual [ncbi.nlm.nih.gov]

• Headache

  Over-the-counter medications may be used for fever and headache. Individuals with encephalitis or bacterial meningitis are usually hospitalized for treatment. [web.archive.org]

  Symptoms The patient typically has a fever, headache, and photophobia (excessive sensitivity to light). There may also be general weakness and seizures. [medicalnewstoday.com]

  Symptoms include headache, fever, confusion, drowsiness, and fatigue. More advanced and serious symptoms include seizures or convulsions, tremors, hallucinations, and memory problems . [commons.wikimedia.org]

  Symptoms include high fever, headache, sensitivity to light, stiff neck and back, vomiting, confusion and, in severe cases, seizures, paralysis and coma. Infants and elderly people are particularly at risk of severe illness. [who.int]

• Amnesia

  Here, we describe a 26-year-old woman who presented with psychosis, amnesia, rigidity and fever. [ncbi.nlm.nih.gov]

  E.C Miotto, Cognitive Rehabilitation of Amnesia After Viral Encephalitis. H. Emslie, B.A Wilson, K. Quirk, J.J Evans, P. Watson, Using a Paging System in the Rehabilitation of Encephalitis Patients. E. Berry, N. Kapur, L. Williams, S. Hodges, P. [routledge.com]

  Symptoms of viral encephalitis The symptoms of viral encephalitis include: high temperature headache sensitivity to light (photophobia) general malaise stiff neck stiff back vomiting changes to personality confusion memory loss (amnesia) seizures paralysis [betterhealth.vic.gov.au]

  Survivors may have Korsakoff's amnesia, because of bilateral damage of the hippocampus, dementia, and seizures. Adult HSV encephalitis. Hemorrhagic necrosis of the temporal and frontal lobes. HSV encephalitis. [neuropathology-web.org]

  Mireia Moragas-Garrido, Colin Goudie, Conrad Schmoll, Stephen Madill, Andrew Farrall and Richard Davenport, Seizure, dysphasia, blindness and amnesia; what's the connection?, Practical Neurology, 13, 5, (331), (2013). [doi.org]

• Stupor

  […] recognize: Body stiffness Irritability and crying more often (these symptoms may get worse when the baby is picked up) Poor feeding Soft spot on the top of the head may bulge out more Vomiting Emergency symptoms: Loss of consciousness, poor responsiveness, stupor [nlm.nih.gov]

  Additional symptoms include drowsiness with general weakness (stupor), and confusion or disorientation. [rarediseases.org]

  There is a broad range of possible manifestations of altered mental status including personality changes, irritability lethargy, stupor, or coma. [infectiousdiseaseadvisor.com]

• Spastic Paralysis

  Severe disease is characterized by rapid onset of high fever, headache, neck stiffness, disorientation, coma, seizures, spastic paralysis and ultimately death. The case-fatality rate can be as high as 30% among those with disease symptoms. [who.int]

In addition to standard blood and urine tests, studies should be done to know the infectious agent causing the encephalitis [7].
Blood cultures for bacterial pathogens should be done. Herpes simplex virus (HSV) cultures of doubtful lesions should be done along with a Tzanck smear.

Spinal tap (Lumbar puncture): With the help of this procedure, the physician can examine the cerebrospinal fluid for any infection or inflammation of the brain. Diagnosis is made by detecting antibodies in the cerebrospinal fluid against a specific viral agent or by polymerase chain reaction that amplifies the RNA or DNA of the virus responsible. Serological tests may show high antibody titre against the causative antigen. The leucocyte count might be high and glucose levels might be disturbed.

Brain imaging: A CT scan of the head with and without contrast should be performed in all cases encephalitis. This should be done before performing lumbar puncture if there are focal complaints or findings, signs to search for confirmation of increased intracranial pressure, obstructive hydrocephalus, or mass effect due to focal brain infection. Head CT scanning also helps in ruling out the possibility of brain haemorrhage or infarction as a cause of the encephalopathic state. An Magnetic resonance imaging (MRI) is better than CT scanning as it offers better resolution in demonstrating brain abnormalities earlier in the disease course.

Electroencephalogram (EEG) can be done to record the electrical activity of the brain. Some peculiar patterns in this activity can be related to the diagnosis of encephalitis, for e.g. in HSE, EEG often documents characteristic paroxysmal lateral epileptiform discharges (PLEDs), even before neuroradiography changes.

Brain biopsy: In case the patient is not responding to the treatment and is still worsening, a brain biopsy may be performed to obtain samples of the brain tissue. A brain biopsy is 96% sensitive and 100% specific.

• Periodic Lateralized Epileptiform Discharges

  The presence of periodic lateralized epileptiform discharges (PLEDs) is associated with HSV encephalitis but may also be consistent with seizure activity, EBV encephalitis, subacute sclerosing panencephalitis due to measles virus, or prion disease. [cancertherapyadvisor.com]

  The classical findings in herpes encephalitis are periodic lateral epileptiform discharge and hyper intense T2-weighted signal in the temporal lobe on MRI however these findings are nonspecific[50]. [intechopen.com]

The target of treatment for acutely ill patients with viral encephalitis is receiving the first dose of acyclovir [8] as soon as possible. In otherwise stable patients, elevating the head and monitoring neurologic status usually are sufficient. When more aggressive treatment is indicated, early use of diuretics (e.g. furosemide 20 mg IV, mannitol 1 g/kg IV) might be helpful, provided that circulatory volume is guarded. Dexamethasone 10 mg IV every 6 hours helps in managing edema surrounding space-occupying lesions. Hyperventilation (arterial CO2 tension (PaCO2) 30 mm Hg) may cause a disproportional decrease in cerebral blood flow (CBF), but it is used to control increasing ICP on an emergency basis. Ganciclovir is another antiviral drug that is used to treat some types of herpes encephalitis.

Empiric adult emergency treatment for herpes simplex virus (HSV) meningoencephalitis and varicella-zoster virus (VZV) encephalitis consists of acyclovir 10 mg/kg (infused over 1 h) every 8 hours for 14-21 days. Physician might use acyclovir 10-15 mg/kg IV every 8 hours for neonatal HSV; for HSV encephalitis in the pediatric population, acyclovir 10 mg/kg IV every 8 hours might be used. Apart from this other encephalitis treatment aims at reducing symptoms.

• Seizures can be prevented by giving oral anticonvulsant drugs or intravenous lorazepam.
• Corticosteroids should be given to reduce brain swelling and pressure within the skull.
• Sedatives may be used to reduce irritability and restlessness.
• Mild cases may be treated using simple pain relieving medications for fever and headache, fluids, and bed rest.

After the initial illness, it may be necessary to receive additional therapy depending on the type and severity of complications. This therapy may include physical therapy, speech therapy, occupational therapy and psychotherapy.

Prognosis depends chiefly on the etiology and health status of the patient. Patients in extremes of age i.e. <1 yr or >55 yrs, immunocompromised, already suffering from neurologic conditions have poorer outcomes. Patients who remain untreated or those receiving late treatments suffer from long-term motor and mental disabilities.

Viral agents like Herpes simplex virus (HSV) type 1 and 2, Varicella zoster virus (VZV), Epstein-Barr virus, Rabies virus, Polio virus, Measles virus, Mumps virus and Rubella virus are the commonest cause of encephalitis. Human herpesvirus 6 (HHV-6) may also be a causative agent [1] [2].

Other causes include infection by flaviviruses like Japanese encephalitis virus, St. Louis encephalitis virus or the West Nile virus. Eastern equine encephalitis virus (EEE virus), Western equine encephalitis virus (WEE virus) or Venezuelan equine encephalitis virus (VEE virus), Variola minor virus and Variola major virus can also lead to encephalitis. Hendra (HeV) and Nipah (NiV), [3] are also known to cause viral encephalitis. Animal vectors like mosquitoes and ticks spread the arbovirus group of viruses and warm-blooded mammals are vectors for rabies and lymphocytic choriomeningitis.

Other causes of encephalitis include:

• Bacteria (as in syphilis or Lyme disease)
• Parasitic or protozoal infestations
• Autoimmune diseases

People at extremes of age are at greater risk, especially for herpes simplex encephalitis which has an incidence of 2-4 per million population per year [4]. In Western countries, the incidence of acute encephalitis is 7.4 cases per 100,000 people yearly, whereas in tropical countries it is 6.34 [5]. In 2010, it lead to around 120,000 deaths, whereas it caused 144,000 deaths in 1990 [6].

The means of entry for the causative agent are specific. Lot of viruses are transmitted by humans, although many cases of Herpes simplex encephalitis are considered to be a reactivation of HSV that was dormant in the trigeminal ganglia.

Mosquitoes or ticks inject the arbovirus and the rabies virus is passed through an infected animal bite or coming in contact with animal secretions. For viruses like VZV and cytomegalovirus (CMV), an immuno-compromised state is generally needed to develop clinically visible encephalitis. Basically, the virus replicates outside the CNS and gets entry into the CNS via hematogenous spread or by travelling along the neural pathways (e.g. rabies virus, HSV, VZV).

As soon as the virus crosses the blood-brain barrier it enters the neural cells, resulting into disturbance of cellular functioning, perivascular congestion, haemorrhage, and scattered inflammatory response which affects the gray matter over white matter unevenly. Viruses affect certain specific areas of the brain because of neuron cell membrane receptors that are found only in certain areas of the brain. For example, HSV is inclined to affect the inferior and medial temporal lobes.

In comparison with viruses that infect the gray matter, infections due to measles, EBV and CMV resulting into acute disseminated encephalitis and postinfectious encephalomyelitis are immune-mediated processes leading to multifocal demyelination of the perivenous white matter.

Vaccination is available against tick-borne encephalitis [9] and Japanese encephalitis [10] and should be considered for at-risk individuals. The risk for mosquito-borne infections is maximum between dusk and dawn. A good quality mosquito repellent helps in decreasing the risk of vector-borne disease. Applying the insect repellent DEET to the skin and also using permethrin for clothes plays an important role in personal hygiene.

Home environment, personal hygiene, and clothing choice can also help reduce the risk of mosquito bites:

• It is necessary to cover well with full-sleeved clothing and full-length pants, at dusk.
• One must sleep only in screened areas.
• Air-conditioning may help reduce mosquito infestation and if not air-conditioning, fans may also do the needful.
• One must avoid using perfumes as they tend to attract mosquitoes.
• Wash hair at least twice a week.

Encephalitis is an inflammation of the brain tissue. Although it primarily involves the brain, meninges are frequently involved. Viral infections are the most common cause of encephalitis.

Encephalitis is the inflammation of brain caused mainly due to a viral infection. The affecting virus can enter your body through other infected human beings or through animals. Once inside the body, the virus starts showing the symptoms of the disease that are similar to common flu. As the disease progress, it leads to neurological symptoms like confusion, paralysis, hallucinations, lethargy, neck stiffness and pain, headache, photophobia, etc.

In extreme cases of encephalitis, the brain swells in the skull and puts downward pressure on the brain stem. The brain stem controls all the important functions, such as respiration and heartbeat. If the pressure becomes too much, these vital functions can stop leading to death.

Early and prompt treatment [11] of this disease can help in complete recovery and if time lapses in obtaining the treatment, person can suffer some loss in his motor or mental abilities. Personal hygiene and hygiene of your vicinity plays an important role in keeping this disease at bay.

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3. Chadha M, Comer J. A. Lowe, L. Rota, P. A. Rollin, et al. Nipah Virus-associated Encephalitis Outbreak, Siliguri, India. Emerg Infect Dis. 2006 Feb; 12 (2): 235–40.
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8. Widener RW, Whitley RJ. Herpes simplex virus. Handb Clin Neurol. 2014;123:251-63.
9. Ishikawa T, Yamanaka A, Konishi E. A review of successful flavivirus vaccines and the problems with those flaviviruses for which vaccines are not yet available. Vaccine. 2014 Mar 10;32(12):1326-37.
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11. Sili U, Kaya A, Mert A. HSV Encephalitis Study Group. Herpes simplex virus encephalitis: clinical manifestations, diagnosis and outcome in 106 adult patients. J Clin Virol. 2014 Jun;60(2):112-8.