Japanese Encephalitis Virus; A Mosquitoe Borne Disease

Mosquitoes indeed cause a lot more damage than malaria, we know how dangerous malaria can be in this part of the world, but we also know that there are different breeds of mosquitoes, and some of them cause other types of infections or diseases.

The mosquito-borne flavivirus we would be talking about today belongs to the same genus as dengue, yellow fever, and West Nile viruses. Japanese encephalitis virus JEV is the most important cause of viral encephalitis in Asia.

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The first case of this virus was documented in Japan in the year 1871. It is rare but a serious form of infection that can happen to anyone, it is not found in all areas of Asia, it is believed to only exist in the rural parts and is believed not to be present in the United Kingdom also.

Most cases of JEV Infections are mild, giving no apparent symptoms, but about 1 amongst 250 cases of infections lead to serious clinical illness. The phase of incubation is within 4-14 days. When children are affected, it comes with symptoms of vomiting, and gastrointestinal pain.

There are usually no symptoms at all for most adults except for flu-like symptoms like; stomach pain, feeling sick, headache, and a high temperature. These symptoms would even likely go away on their own, but this is not always the case as some people have the infection spread to the brain causing more serious symptoms like; confusion, serious headache, stiff neck, coma seizures, paralysis, and sudden death.

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Of those who can survive this stage of chronic infection, about 20-30 percent of them end up suffering permanent intellectual, behavioural, or neurological sequelae like; recurrent seizures, paralysis, or even the inability to speak.

There is a high risk of transmission of this virus, and it is transmitted to humans through bites from an infected mosquito of the Culex species basically Culex tritaeniorhynchus. Once humans get infected, they do not develop enough viraemia to infect a feeding mosquito, the virus is transmitted in circles amongst pigs, mosquitoes, and water birds. The disease is more predominant in rural and periurban settings, where humans live at very close intervals with each other and vertebrate hosts.

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The transmission is more common during the warm season when large epidemics can happen, but in the tropics and subtropics, transmission can happen all through the year, however, intensifies itself during the rainy season and pre-harvest period.

Japanese encephalitis could be a life-threatening condition, so upon infection, there may be a need to stay at the hospital for close monitoring. There is no antiviral treatment for this case, but supportive treatments made available can help relieve symptoms and also help stabilize affected patients.

The good thing is to prevent a disease or virus from getting to you if there is a way to do that before it even happens, especially in this case where there are no antiviral treatments. There are vaccines available to help prevent the disease. The provision of immunization in all regions where the disease has been recognized makes it a public health priority, along with a strong reporting mechanism and strengthening surveillance.

Even when the number of people infected with JE is confirmed low, vaccination needs to be provided in such an environment. There are four main types of vaccine available currently;

• Inactivated mouse brain-derived vaccine.
• Inactivated Vero cell-derived vaccines.
• Live recombinant vaccines.
• Live attenuated vaccines.

Travelers going to Japanese encephalitis-endemic areas need to take caution and avoid mosquito bites, taking advantage of existing personal preventive measures including putting on long clothes and using mosquito repellants, coils, and vaporizers. In addition to this, get vaccinated also.

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who.int/news-room/fact-sheets/detail/japanese-

cdc.gov/travel/diseases/japanese-encephalitis

cdc.gov/japanese-encephalitis/hcp/vaccine

nhs.uk/conditions/japanese-encephalitis/

healthdirect.gov.au/japanese-encephalitis