Introduction

Japanese encephalitis is an infection transmitted through the bite of a mosquito which carries the virus.¹ While rare in the UK, it is prevalent in Eastern and Southern Asia, particularly in the rural areas of Japan, China, India, South Korea and Indonesia.^1,2 Each year, an estimated 40,000 cases have been identified, with 10,000 deaths. However, some may argue that the true impact is much more severe, with 175,000 cases annually.¹ 

Due to the nature of the disease and its neurological consequences, which will be explored later, it is the leading cause of childhood viral neurological disability in Asia.¹ This is why timely management is very important. 

Japanese encephalitis has been recorded since 1871, but the first outbreak occurred in 1924 in Japan with a mortality rate of 60%.¹ While the mortality rate has since decreased, the long-lasting neurological consequences can affect people for life. In some cases, patients may become paralysed, develop seizures or be unable to return to university/employment.³ The impact of Japanese encephalitis is greater in rural areas, where people may lack proper medical care and support. This is why it is crucial to discuss how the disease can be managed in said rural areas.

Impact of Japanese encephalitis in rural areas

In most cases, Japanese encephalitis begins as an asymptomatic infection.² If the disease remains asymptomatic, there is a greater chance that the patient will make a full recovery. Severe cases of the disease are characterised by rapid onset of high fever, neck stiffness, disorientation, coma, seizures and eventually death. For these patients, the mortality rate can be as high as 30%. In the group of patients who survive, a portion suffer from long-lasting neurological symptoms, such as seizures, hearing loss, vision loss, problems with communication, speech and memory, and weakness of the limbs⁴. 

Japanese encephalitis is commonly transmitted through mosquito bites. However, it can be contracted through close contact with domestic pigs and water birds as well. Outbreaks tend to occur in rural areas, where people may live in close contact with domestic pigs and do not have access to vaccination programmes. The World Health Organisation recommends the implementation of vaccination programmes in all countries affected affiliated with Japanese encephalitis. They advise prioritising vaccinating humans and eventually including pigs as well, given their role as a vector of the disease.⁴ 

Another risk for the transmission of the disease is rice farms, where the water reservoir attracts mosquitoes. The mosquitoes may settle and lay their eggs, putting the nearby human population and domestic pigs at risk.⁵ 

Although accurate information on the burden of Japanese encephalitis in each affected country is lacking, the Australian government pledged $69 million for its response to the virus. A breakdown of the budget highlights the significant burden of Japanese encephalitis in regions with high case numbers: $28.18 million for the purchase of new vaccines, $17.5 million to implement mosquito surveillance activities, $5 million for public health education and communication, $3.5 million to enhance laboratory testing capabilities, $4 million to map affected areas, and $10 million to support agricultural departments.⁶ 

All of these are essential steps that highlight the significant resources required to manage the disease, illustrating why it may be challenging for every affected country to fund these prevention measures. In the next section, we will discuss how to manage Japanese encephalitis from both a medical and a societal standpoint.

Management of Japanese encephalitis in rural areas

The management of Japanese encephalitis involves a range of initiatives, including medical, governmental and environmental measures. It is important to tailor these management plans to rural areas, bearing in mind that clinics and vaccination centres may not be accessible to everyone. They should also address the challenges people face to decrease the disease burden.

Globally, the main strategy to reduce the number of cases of Japanese encephalitis is vaccination. The vaccine can be given to children and adults, followed by two booster doses. It has a few side effects that are common among individuals, such as diarrhoea, fever and abdominal pain.⁷ There are two main variants of the vaccines: JEspect and Imojev. They are considered to be 94- 96% effective in preventing the disease.⁸ However, being vaccinated doesn’t mean you are completely safe from contracting the virus. Furthermore, the vaccine is expensive, which may mean that people in rural areas may not be able to afford it, or travel to a vaccine clinic.⁹ It is important that vaccines be readily accessible in rural areas, and educational programmes be implemented to impress the importance of getting vaccinated.

Another strategy to manage Japanese encephalitis in rural areas is reducing the exposure to mosquitoes. Mosquitoes are the main vector of disease, and as such, need to be targeted. Some simple measures to avoid mosquitoes are wearing long clothing, installing mosquito nets and spraying them with insecticide, and wearing insect repellent.¹⁰ These measures keep mosquitoes away. However, in areas such as rice farms, where the risk of mosquito bites remains high due to the proliferation, vaccination continues to be the safer option.

Another form of management is to employ resources to organise and deliver educational programmes on Japanese encephalitis. People in rural areas may not be as informed about the disease and its severity, symptoms or how to get help if the disease progresses. It is important that they are given accurate information to prevent contraction and reduce the disease burden. It is also important to support people in rural areas in making agricultural changes to avoid attracting mosquitoes and protect the domestic pigs.¹¹ 

Lastly, there is currently no specific medical treatment for Japanese encephalitis. Treatment plans focus on managing symptoms and helping people in their recovery. Further investigation is needed to find an appropriate treatment, but several drugs of interest are already being studied. 

For instance, a study looking at different types of steroids in the management of Japanese encephalitis found that minocycline had promising results.¹¹ Although it didn’t reduce the mortality rate of the disease, it helped reduce symptoms and overall outcome in patients who survived the first day of hospitalisation. The study had some limitations, such as a small population group from one specific geographical area. Finding a drug that helps reduce symptoms and aids recovery is encouraging for the management of Japanese encephalitis.¹²

FAQs

How do I know if I am at risk of contracting Japanese encephalitis?

If you live in the UK, you are not considered to be at risk of catching Japanese encephalitis. However, if you are planning to travel to Eastern or Southeast Asia, specifically rural areas, you may be exposed to the virus.

How do I avoid contracting Japanese encephalitis if I travel to rural areas in Asia?

• Get vaccinated, if possible
• Use insect-repellent spray on your skin
• Sleep under a mosquito net treated with insecticide
• When possible, wear clothes that cover your skin
• Avoid domestic pigs

What is the incubation period of Japanese encephalitis?

Typically 6-8 days, but it can range from 4-15 days.¹³

Summary

Japanese encephalitis is an infection primarily carried by mosquitoes. It is prevalent in South and Eastern Asia, particularly in rural areas. They suffer the devastating consequences of the disease, which can lead to neurological disability, problems with memory and speech and movement. Management of Japanese encephalitis can be a challenge and expensive. However, it is important to reduce the burden of the disease. Some strategies to manage the disease in rural areas include implementing vaccination programmes, enforcing environmental and education measures, taking preventative actions to avoid mosquitoes, and conducting research to discover potential treatments, such as minocycline.