The disease presents in 3 stages, first is the acute stage (1-2 weeks), second subacute stage (more than 2 weeks) and the third stage lasting for several weeks to months [4].

Initially, patients present with fever with chills and rigors, malaise, and headache lasting for 1 to 6 days. Thereafter, there is an encephalitic stage in which there is marked neck stiffness, cachexia, reduced levels of consciousness. The third stage includes flaccid paralysis, features of Parkinson’s such as masked face, tremors, hypertonia, cogwheel rigidity.

In some reported cases there has been death due to brain death or respiratory arrest. There are many residual symptoms which patients suffer lifelong even after recovery from active infection such as language impairment, altered mental status and cognitive impairment [5].

• Fever

  Fact sheet No 386 December 2015 Key facts Japanese encephalitis virus (JEV) is a flavivirus related to dengue, yellow fever and West Nile viruses, and is spread by mosquitoes. [web.archive.org]

  Horses Three clinical syndromes are described: Transient type — fever anorexia, sluggish movement, congested or jaundiced mucous membranes, and uneventful recovery; Lethargic type— fluctuating fever, pronounced lethargy, anorexia, difficulty in swallowing [lrd.spc.int]

  Fever, headache, and vomiting were the most common symptoms in both the E30 and the JEV groups. [ncbi.nlm.nih.gov]

• High Fever

  Four days after returning to Australia the patient presented with a high fever, stupor and rapidly-developing focal neurological signs. Recovery occurred gradually over a period of three months and she has returned to school. [ncbi.nlm.nih.gov]

  However, a small percentage of infected persons develop inflammation of the brain (encephalitis), with symptoms including sudden onset of headache, high fever, disorientation, coma, tremors and convulsions. About 1 in 4 cases are fatal. [web.archive.org]

  However, a small percentage of infected people develop inflammation of the brain (encephalitis), with symptoms including sudden onset of headache, high fever, disorientation, coma, tremors and convulsions. About 1 in 4 cases are fatal. [cdc.gov]

• Chills

  The flu-like symptoms include fever, chills, fatigue, headaches, nausea and vomiting. The virus can also affect the CNS, causing encephalitis with reduction of consciousness, cramping seizures, impaired reflexes, paresis and signs of meningitis. [flexikon.doccheck.com]

  On average, 1 in 300 infections results in symptomatic illness, which is characterized by a flu-like illness with sudden onset of fever, chills, headache, tiredness, nausea, and vomiting. [vaccineresources.org]

  One in every 250 of those infected with the JE virus will succumb to severe illness, with an onset characterized by flu-like symptoms (sudden onset of high fever, chills, headache, and tiredness). [doh.gov.ph]

  Symptoms include high fever, chills, headache, and fatigue. Japanese encephalitis can rapidly lead to infection of the brain. According to the DOH, 3 out of 10 individuals who experience severe illness from the disease will die. [rappler.com]

  Japanese encephalitis can present with fever, chills, headache, muscle pain and spasm, movement disorders, seizures (particularly in children) and a reduction in the level of consciousness. [encephalitis.info]

• Rigor

  At the onset of the disease patients present with severe rigors, fevers and headache. As it progresses to the acute encephalitic stage, meningo-encephalitic symptoms such as a neck rigidity, cachexia, hemiparesis and convulsions become prevalent. [radiopaedia.org]

  Initially, patients present with fever with chills and rigors, malaise, and headache lasting for 1 to 6 days. Thereafter, there is an encephalitic stage in which there is marked neck stiffness, cachexia, reduced levels of consciousness. [symptoma.com]

  Unfortunately, only a handful of laboratories in developed countries are actually involved in any rigorous study involving JEV. [doi.org]

  […] was first described in 1871.[2] Signs and symptoms[edit] The Japanese encephalitis virus (JEV) has an incubation period of 2 to 26 days.[4] The vast majority of infections are asymptomatic: only 1 in 250 infections develop into encephalitis.[5] Severe rigors [en.wikipedia.org]

• Fatigue

  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]

  The flu-like symptoms include fever, chills, fatigue, headaches, nausea and vomiting. The virus can also affect the CNS, causing encephalitis with reduction of consciousness, cramping seizures, impaired reflexes, paresis and signs of meningitis. [flexikon.doccheck.com]

  The most common side effects following JE vaccination are injection site pain, headache, fatigue and generally unwell with most symptoms resolved within 3 days. [conditions.health.qld.gov.au]

  Symptoms include high fever, chills, headache, and fatigue. Japanese encephalitis can rapidly lead to infection of the brain. According to the DOH, 3 out of 10 individuals who experience severe illness from the disease will die. [rappler.com]

• Vomiting

  Fever, headache, and vomiting were the most common symptoms in both the E30 and the JEV groups. [ncbi.nlm.nih.gov]

  Initial symptoms often include fever, headache, and vomiting. Mental status changes, neurologic symptoms, weakness, and movement disorders might develop over the next few days. Seizures are common, especially among children. [web.archive.org]

• Nausea

  A 58-year-old woman presented with high fever, headache, nausea, vomiting, and consciousness disturbance. [ncbi.nlm.nih.gov]

  Symptoms include high fever, headaches, weakness, nausea, vomiting, paralysis, personality changes, and coma, possibly leading to neurological damage or death. [rarediseases.org]

  Typical encephalitis symptoms include nausea and vomiting, seizures, headaches and confusion. The Japanese encephalitis virus affects the human brain and can lead to inflammation and swelling in the brain. [onlinedoctor.superdrug.com]

  The flu-like symptoms include fever, chills, fatigue, headaches, nausea and vomiting. The virus can also affect the CNS, causing encephalitis with reduction of consciousness, cramping seizures, impaired reflexes, paresis and signs of meningitis. [flexikon.doccheck.com]

• Hypertension

  Eclampsia is clinically characterised by encephalopathy, seizures, headache and cortical blindness and occurs in the setting of pre-eclampsia that comprises hypertension, proteinuria and peripheral oedema. [ncbi.nlm.nih.gov]

  […] in a patient who had mononucleosis ; one case of urticaria, hepatitis, respiratory failure, eosinophilia, and pulmonary effusion and infiltrate; respiratory and renal failure in a patient with acid fast bacilli in sputum and pulmonary infiltrate; and hypertension [drugs.com]

  Seven patients had history of chronic diseases, such as hypertension and diabetes; there was no evidence of any immune compromising condition. The number of comorbidities was significantly different between the two groups. [frontiersin.org]

  Those with greater outdoors exposure Individuals > 50 years of age Children History of chronic conditions such as History of solid organ transplant Cochlear implants, ventriculoperitoneal shunts and other devices impinging on the central nervous system Hypertension [tdtmvjournal.biomedcentral.com]

  Hypertension, diabetes mellitus, and coinfection with other virus may further deteriorate the infection and can worsen the condition of infected persons by increasing neurological complications which may happen due to facilitation of virus across the [intechopen.com]

• Tachycardia

  Bulbar poliomyelitis was initially considered due to the clinical features of aseptic meningitis, respiratory paralysis, pharyngeal paralysis with pooling secretions in the pharynx, tachycardia and elevated blood pressure. [ncbi.nlm.nih.gov]

• Photophobia

  It may also involve photophobia, hyperexcitability and focal and neurological signs, including dull, mask-like faces, muscular rigidity, cranial nerve palsies, tremulous eye movements, coarse tremors of the extremities generalized and localized paresis [futuremedicine.com]

  These may be followed by a combination of nuchal rigidity, photophobia, altered consciousness, hyperexcitability, masked facies, muscle rigidity, cranial nerve palsies, tremulous eye movements, tremors and involuntary movement of the extremities, paresis [dx.doi.org]

  […] manifestations of the disease depend on which part of the nervous system is affected and include early symptoms, such as nonspecific febrile illness, viz. diarrhea and rigor, followed by symptoms such as reduced levels of consciousness, seizures, headache, photophobia [doi.org]

• Headache

  Non-encephalitic disease : acute febrile illness with headache, myalgia and/or rash OR 2. [health.gov.au]

  Fever, headache, and vomiting were the most common symptoms in both the E30 and the JEV groups. [ncbi.nlm.nih.gov]

  • Most infections are mild (e.g., fever and headache) or without apparent symptoms. [vaccineinformation.org]

• Seizure

  CONCLUSION: Seizure and behavioral abnormality are common features in HSE whereas focal reflex loss is commoner in JE. In a patient with acute encephalitis, thalamic lesion suggests JE and temporal lobe involvement HSE. [ncbi.nlm.nih.gov]

  In some cases, patients with Japanese encephalitis can be given anti-seizure medicines to prevent seizures and corticosteroid drugs to reduce brain swelling. The incubation period for Japanese encephalitis is typically five to 15 days. [wikihow.com]

  In the severe cases, the treatment aims to manage seizures and raised intracranial pressure (due to brain inflammation) and support breathing. [encephalitis.info]

• Confusion

  Initially, a flu-like illness may occur, which may progress to brain swelling, resulting in symptoms such as high fever, confusion, convulsions, headache, neck stiffness and paralysis. [londontravelclinic.co.uk]

  Mental retardation, nausea Onset of mental issues like seizures, confusion, disorientation, tremors and hallucinations. 50 to 60 percent people, who suffer from this disease can not survive it. [oneindia.com]

• Meningism

  We therefore aimed to identify reliable clinical methods to differentiate E30 and JEV acute meningitis/encephalitis. A retrospective, cross-sectional study was conducted to compare E30 and JEV acute meningitis/encephalitis cases. [ncbi.nlm.nih.gov]

  Clinical signs may include meningeal signs, stupor, disorientation, coma, tremors, generalised paresis, hypertonia, and loss of coordination. [health.gov.au]

  The virus can also affect the CNS, causing encephalitis with reduction of consciousness, cramping seizures, impaired reflexes, paresis and signs of meningitis. In about 20% these cases lead to the death of the patient. [flexikon.doccheck.com]

• Paresis

  Clinical signs may include meningeal signs, stupor, disorientation, coma, tremors, generalised paresis, hypertonia, and loss of coordination. [health.gov.au]

  The virus can also affect the CNS, causing encephalitis with reduction of consciousness, cramping seizures, impaired reflexes, paresis and signs of meningitis. In about 20% these cases lead to the death of the patient. [flexikon.doccheck.com]

  […] erythema nodosum, joint swelling, respiratory distress, hypotension, and collapse. [ Ref ] Nervous system Nervous system side effects have rarely included encephalitis, encephalopathy, seizures, peripheral neuropathy, transverse myelitis, cranial nerve paresis [drugs.com]

  […] epidemic viral encephalitis, it has an incidence of ± 0.5/1000; JE is often fatal or crippling, especially in Thailand Clinical Abrupt onset with fever, headache, meningeal irritation, convulsions, muscular rigidity, mask-like facies, coarse tremor, paresis [medical-dictionary.thefreedictionary.com]

  The case fatality rate in patients with severe disease is 20- 30% and about 30% of the patients surviving the illness have significant neurological sequelae (motor paresis, spasticity, movement disorders, chronic seizures, and developmental delay). [ecdc.europa.eu]

After clinical research done on affected patients it was found that the diagnosis for virus cannot be obtained through clinical specimens and thus is done by testing the serum or the cerebrospinal fluid (CSF) for virus specific IgM antibodies. This is the standard test to confirm Japanese encephalitis [5].

Other tests include complete blood counts showing leucocytosis along with thrombocytopenia. MRI scans shows lesions in the thalamus with abnormalities in the basal ganglia, putamen, cerebellum and spinal cord.

Electroencephalography (EEG) reveals changes in the spike pattern and slowing of delta waves.

• Hyponatremia

  Poor prognostic factors include low Glasgow coma scale (GCS), hyponatremia, and age younger than 10 years. See Prognosis for more detail. [emedicine.com]

There is no specific treatment for Japanese encephalitis. The reason for mortality in children is delay in immediate nursing care. The aim is to restore airway, breathing and circulation. Basic life support and nutrition is taken care through intravenous fluids. Special care is necessary to avoid any rise in the intracranial pressure.

Mannitol is administered in a lower dose especially in children having a Glasgow coma score (GSC) less or equal to 8. Control of seizures is done by giving antiepileptic drugs such as phenobarbitone. Rectal diazepam also can be administered if necessary. Fluids and sodium infusion or feeds are given amply to restore the hydration and nutrition [6].

Japanese encephalitis has a high mortality rate especially in children. Several studies showed that children with high fever, leucocytosis in CSF and coma had a bad prognosis. Cases which had a tumor necrosis factor (TNF) concentration of more than 50 had a fatal outcome as opposed to those who had a high concentration of Japanese encephalitis virus antibodies in the CSF.

There are many long standing after-effects or changes in those who survive. These are speech defects, motor deficits, memory loss and Parkinsonism.

Japanese encephalitis is caused by a flaivirus. Flavivirus belongs to the family flaviviridae. The shape of this virus is spherical and is 40-50 nm in diameter. It is a single stranded RNA virus. It has 3 structural and 7 non structural proteins. These proteins have an outer layer of a domaine which does the attachment, haemagglutination and neutralization.

This virus is transmitted to humans through a bite of an infected mosquito. The mosquito usually breeds in marshy areas or rice fields. It is a non contagious infection.

Japanese encephalitis (JE) – has been frequently found in Asian countries, its incidence has been increasing in India as well. The pediatric age group of 5-10 years has been most widely affected. The Japanese encephalitis infection is suspected to be one of the major health problems across India with a mortality rate of 20 to 50 %. Statistics show that in southern India, children less than 15 years are affected and in northern India, children affected are above 15 years of age.

It is necessary to provide vaccines to protect the individual from the disease; while it is also necessary to immunize the pigs (hosts) to prevent the disease transmission [2]. It has been observed that in all epidemics, males are affected more than females.

Japanese encephalitis is a type of infection in which the host in unable to produce any antibodies against this virus, thereby allowing it to cross the blood brain barrier and produce brain infestations. Japanese encephalitis develops after an incubation period of 5-15 days in patients during which the virus multiplies within the leucocytes of the host [3].

In the acute stage, there is congestion, thrombus formation, severe damage to the nerve cells, injury to the brain parenchyma such as minute necrosis, softening and perivascular cuffing. The areas of the brain affected are the diencephalon, mescencephalon, parts of the brain stem, cerebral cortex and the cerebellum.

In the subacute stage, the congestion and inflammation is less but the degeneration of nerve cells and proliferation of the glial cells is more dominant and the lesions are more localized. In the final or the chronic stage, there is marked destruction resulting in disappearance of the nervous tissue, local necrosis, vascular thickening especially in the substania nigra [4].

Protection from mosquito bites by using an insect repellent, mosquito nets, pesticides and environmental sanitation.

Vaccination is encouraged in children of the age group of 2 to 15 years. The Japanese encephalitis vaccine is a formalin inactivated vaccine obtained from the brain of mice. Studies say protective immunity is achieved after numerous doses. Two doses are given at an interval of 7-14 days. Thereafter a booster injection is given after a gap of 4 weeks.

Japanese encephalitis is a vector borne viral disease caused by Japanese encephalitis virus that is transmitted by an infected mosquito commonly called culex tritaeniorrhynchus [1].

This disease was first discovered in India in the year 1955, in Tamil nadu. It is still prevalent there, along with other states like from Uttar Pradesh, Karnataka, Assam, Bihar, Pondicherry, West Bengal, Andhra Pradesh, Manipur, and Goa and recently new cases have also been reported from the states of Kerala and Maharashtra.

Japanese encephalitis infection is a viral infection caused by Japanese encephalitis virus. It is transmitted to humans via infected mosquito. This infection is commonly found in Asian countries and children of 2 to 15 years are largely infected.

This disease affects one’s nervous system. The symptoms are mainly fever, headache, vomiting, and neck stiffness. Convulsions muscle rigidity, loss of consciousness is seen as the disease progresses.

There is no specific treatment of this infection. The patient requires immediate hospitalization to secure his breathing and circulation. Vaccination and protecting from mosquito bites is the main step for preventing such a disease.

1. Erlanger T, Weiss S, Keiser J , Utzinger J, et al. Present, and Future of Japanese Encephalitis. Emerg Infect Dis. Jan 2009; 15(1): 1–7
2. Kabilan L, Rajendran R, Arunachalam N, Ramesh S, Srinivasan SSamuel PPDash AP . Japanese encephalitis in India: an overview. Indian J Pediatr. 2004 Jul; 71(7):609-15.
3. Tom Solomon, Le Thi Thu Thao, Nguyen Minh Dung, Rachel Kneen et al. Rapid Diagnosis of Japanese Encephalitis by Using an Immunoglobulin M Dot Enzyme Immunoassay. J Clin Microbiol. Jul 1998; 36(7): 2030–2034.
4. Masashi Miyake. The pathology of Japanese encephalitis*Revised version of a paper submitted to the Seminar on Japanese Encephalitis and Other Arthropod-borne Virus Infections convened in Tokyo in October 1962 by the WHO Regional Office for the Western Pacific. Bull World Health Organ. 1964; 30(2): 153–160.
5. Debapriya Ghosh and Anirban Basu. Japanese Encephalitis—A Pathological and Clinical Perspective. PLoS Negl Trop Dis. Sep 2009; 3(9): e437.
6. Tiroumourougane SV, Raghava P, Srinivasana S, Badrinath. Management parameters affecting the outcome of Japanese encephalitis. J Trop Pediatr. 2003 Jun; 49(3):153-6.