Here's all you need to know about Japanese Encephalitis and how to prevent it

As Indian government is trying take stock of the Japanese Encephalitis situation to contain the outbreak, here are some measures to prevent transmission of the virus.

Japanese Encephalitis | Image for representational purposes only.

After 22 people died of Japanese Encephalitis in Assam, the Centre has rushed a team to take stock of the situation and to contain the outbreak of the vector-borne disease. Here are some of the measures you can take to prevent transmission of the virus.

What is Japanese Encephalitis?

Japanese Encephalitis Virus is a flavivirus related to dengue, yellow fever and West Nile viruses, and is spread by mosquitoes. This virus is the major cause of Acute Encephalitis Syndrome (AES) in India (ranging from 5%-35%). 

AES due to JEV was clinically diagnosed in India for the first time in 1955 in Tamil Nadu. During 2018, 10485 AES cases and 632 deaths were reported from 17 states. 

Signs and symptoms

According to WHO, symptoms for most Japanese encephalitis infections are mild and include fever and headache. In many cases there aren't any apparent symptoms.

The incubation period is between 4-14 days. In children, gastrointestinal pain and vomiting may be the dominant initial symptoms.

Usually, only 1 in 250 infections results in severe clinical illness. 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 symptoms.

Of those who survive, 20%–30% suffer permanent intellectual, behavioural or neurological sequelae such as paralysis, recurrent seizures or the inability to speak.

How JEV is transmitted

JEV is transmitted to humans through mosquito bite. The virus exists in a transmission cycle between mosquitoes, pigs and/or water birds (enzootic cycle). The disease is predominantly found in rural and periurban settings, where humans live in closer proximity to these hosts.

Prevention and control

Currently, there is no antiviral treatment for patients with Japanese Encephalitis. Available treatment only helps relieve symptoms and stabilize the patient. Hence taking precautions to prevent the disease is a must.

• All travellers to Japanese encephalitis-endemic areas should take precautions to avoid mosquito bites
• Personal preventive measures include the use of mosquito repellents, long-sleeved clothes, coils and vaporizers
• Safe and effective Japanese Encephalitis vaccines are available to prevent disease

What are the available vaccinations?

There are 4 main types of JE vaccines currently used 

• inactivated mouse brain-derived vaccines 
• inactivated Vero cell-derived vaccines
• live attenuated vaccines
• live recombinant (chimeric) vaccines

Over the past years, the live attenuated SA14-14-2 vaccine manufactured in China has become the most widely used vaccine in endemic countries, and it was prequalified by WHO in October 2013. Cell-culture based inactivated vaccines and the live recombinant vaccine based on the yellow fever vaccine strain has also been licensed and WHO-prequalified.