What is Japanese Encephalitis (JE), Causes, Symptoms and Treatment

What is Japanese Encephalitis (JE):

Each year, several thousand people are killed by Japanese Encephalitis (JE). There have also been reports of cases from the Pacific Islands and Australia, in addition to South East Asia and India. In India, Pakistan, South-East Asia, Japan, China, and Russia, encephalitis is caused by this virus. Every year, the WHO reports 10000–20,000 cases of it. In 1955 the first case of the JE virus was reported. The first indication of the virus dates back to 1952. Different parts of the country have been affected by outbreaks. The most common sources of infection are pigs and domestic animals.

What causes Japanese Encephalitis (JE):

It can be transmitted to humans by mosquitoes belonging to the species Culex (mainly Culex tritaeniorhynchus), which breed mostly found in rice paddies. A mosquito carrying Japanese Encephalitis can transmit it by feeding on pigs and wild birds carrying the disease. It cannot be transmitted from person to person. As a result of the dramatic increase in vector populations during rainy seasons, diseases are highly transmitted. There is no cure for the disease, but there are vaccines that can prevent the spread of the disease. By treating the infection, the patient is able to protect themselves from further damage and will be relieved of severe clinical signs.

What are the Symptoms of Japanese Encephalitis (JE):

It takes about 5-15 days for an infection to develop. Some of the symptoms are fever, headache, and vomiting. It is estimated that 1 in 250 infections of the JE virus progress to severe disease, including fever, headache, neck stiffness, disorientation, coma, seizures, spastic paralysis, and death. Symptomatic individuals can experience a 30-per cent fatality rate. Twenty per cent to thirty per cent of those who survive to suffer permanent neurological, cognitive, or behavioural problems such as paralysis, recurrent seizures, and speech impairments.

In childhood, infection is usually subclinical. Fewer than 1% of infections result in encephalitis.

• The initial symptoms include fever
• Malaise,
• Anorexia
• Vomiting
• Headache
• Photophobia,
• Changes in brain stem function.

As a result of an infection with the JE virus, a person may suffer from a fever and neurological symptoms such as headaches, meningitis, or encephalitis. There are several symptoms associated with this disorder, including headache, fever, meningeal signs, stupor, disorientation, coma, tremors, paralysis (generalized), hypertonia, and loss of coordination. It can occur abruptly (within a few hours), acutely (within a few days) or subacutely (2-5 days). The prodromal phase of the acute encephalitic disease is characterized by convulsions, sensorium changes, behavioural changes, motor paralysis, and involuntary motor movements. Focal neurological deficits are also noted.

The symptoms usually last a week, though complications usually prolong them. Many of those who survive will find they are able to recover to their full potential through steady improvements. Some will experience stabilization of neurological deficits, however often takes a few weeks to several months for the convalescent phase to begin. When JE virus infection presents classical symptoms that are similar to those caused by another virus that causes encephalitis, it is difficult to distinguish it from another viral infection.

In addition to encephalitis, neurological disorders such as meningitis, seizures, cranial nerve palsies, and extrapyramidal symptoms can occur. 25% of patients will die from neurological disorders. Infection of brain stem nuclei is often associated with respiratory failure in children.

Diagnosis of JE (Japanese Encephalitis):

Diagnostic tests of blood or spinal fluid are used in combination with clinical signs and symptoms. The body's immune system usually detects viral infections based on antibodies produced.
It cannot be distinguished clinically from encephalitis of viral origin, which presents similar signs and symptoms. In any event, JE can have the potential to cause encephalitis as a febrile illness of variable severity that includes neurological symptoms that range from headaches to meningitis and even encephalitis. 
In addition to the Haemagglutination Inhibition Test (HI), Complement Fixation Test (CF) and Enzyme-Linked Immuno-Sorbent Assay (ELISA) tests, JE virus antibodies can also be detected by several laboratory tests.
The method of choice for detection of IgM is ELISA provided the samples are collected within 3-5 days after infection, as there are limitations associated with various tests.
It is crucial to exclude other infectious causes of encephalitis. Hyponatremia and neutrophilia are common. Lymphocytosis and a high level of protein in the CSF are apparent. There is a CSF antigen test and serological testing may be helpful.

Management of Japanese Encephalitis: 

As a preventive measure, insecticide-treated mosquito nets are used to protect against mosquito bites and reduce vector density. Eco-management is required to reduce mosquito breeding sites as insecticides are not as effective as eco-management. It is best to keep piggeries away from human habitations. 

• A number of factors contribute to the difficulty of preventing and controlling JE.
• Vectors prefer living outdoors.
• Cases are dispersed over a wide geographic area.
• Different reservoir hosts play an important role in the spread of the disease
• Different vectors are present in different geographic and ecological regions
• Various groups of people do not have the same immune status, so identifying vulnerable groups is challenging

JEV vaccines can prevent disease in various groups. Kasauli's Central Research Institute makes the JE vaccine. A series of three doses provides immunity for a few years. The use of vaccination to control outbreaks is not recommended because antibodies are not formed until up to a month after a second dose, and outbreaks are usually short-lived. The clinical management of convulsions in the acute phase is supportive and aimed at maintaining fluid balance and electrolyte balance and controlling convulsions if any.

JE vaccination should be widely implemented across all regions where it is recognized as a public health problem, along with increased surveillance and reporting mechanisms, according to the WHO. The effectiveness of other approaches, such as mosquito control or pig exclusion, has been questioned.

• Current JE vaccines fall into four categories: inactivated mouse brain vaccines, inactivated cell-based vaccines, live attenuated vaccines and live chimeric vaccines. A purified inactivated product derived from Nakayama or Beijing strains propagated in mouse brain tissues was traditionally the most widely used vaccine. A number of countries continue to use this vaccine.
• In order to reduce the risk of Japanese encephalitis, travellers must avoid mosquito bites in areas where the disease is endemic. You can prevent mosquito bites by wearing long sleeves, coils and vaporizers, as well as using repellents.
• Protect yourself by wearing insect repellant. Apply insect repellents or oils of lemon eucalyptus when going outside. The mere act of spending time outdoors can be enough to cause mosquito bites.
• Make sure you are properly dressed to minimize mosquito bites. While outside, wear long sleeves, pants and socks. Thin clothing may be bitten through by mosquitoes, so spraying permethrin-containing repellents or repellents on clothes will provide extra protection versus the natural insect repellent. Permethrin-containing repellents should never be applied directly to the skin.
• Do not go outside during peak mosquito biting hours. In the cooler hours from dusk to dawn, mosquitoes that transmit the JE virus are most active outside. If possible, travellers should limit outdoor activities during these times when they are in high-risk areas. Travellers should use a bed net and aerosol room insecticides to reduce their risk of JE and other vector-borne diseases.

Complications are anticipated and treated in a supportive manner. Prophylactic vaccination during the monsoon season is effective for travellers to endemic areas. This vaccination is included in some endemic country curriculums for children. JE complications are primarily caused by the virus' primary effect on the central nervous system. Numerous survivors suffer from neurological disorders including impaired cognitive function, mental disorders, seizures, and poor coordination. In many Asian countries, JE is the primary cause of viral encephalitis.

According to the WHO, a few important facts about Japanese Encephalitis are as follows: 

• JEV (Japanese Encephalitis Virus ) also known as flavivirus is related to dengue, yellow fever and West Nile viruses, and this disease is caused and spread by mosquitoes.
• Approximately 68 000 clinical cases of JEV encephalitis are reported each year in several countries of Asia.
• Though Japanese encephalitis (JE) is rare when it is symptomatic, as much as 30% of those with encephalitis die. It is estimated that 30%–50% of those with encephalitis will have permanent neurologic or psychiatric problems.
• Over 3 billion people in the WHO South-East Asia and Western Pacific regions are at risk of infection due to endemic JEV transmission.
• This disease is incurable. Clinical signs are alleviated and the patient is assisted to overcome infection through treatment.
• JEV vaccines are safe and effective in preventing the disease. The World Health Organization (WHO) recommends that national immunization schedules include JE vaccination in all countries dealing with this public health issue.