Japanese Encephalitis

Japanese encephalitis (JE) is a virus that can infect both humans and animals. In humans, the virus creates a swelling reaction in the membranes surrounding the brain, potentially causing long-term brain damage to nerves and tissues. The disease is transmitted through mosquito bites, similar to West Nile Virus. In the southern and southeastern regions of Asia, the disease proliferates when rice paddies are irrigated or flooded by rains. At this time, mosquito populations increase and animals and birds often become infected with the disease. When this happens, the disease can be passed to humans living nearby.

Symptoms

When Japanese encephalitis strikes, it usually causes mild symptoms or none at all. Some people might experience a fever or headache without any other symptoms. According to the World Health Organization (WHO), Japanese Encephalitis causes severe symptoms in approximately one out of every 200 infections. A severe case of the disease includes a quick onset of symptoms such as fever, headache, disorientation, stiffness around the neck, seizures, coma, paralysis, and in extreme cases, death. When disease symptoms become apparent, the likelihood of a fatality is approximately 60%. Amongst those who survive after showing symptoms, 30% will have brain damage. However, this occurs primarily in young children who have never been exposed to the disease. In regions where JE is prevalent, most of the older population have already been infected with the virus and therefore possess immunity.

Causes

The virus that causes JE is spread through mosquitoes that live and breed in rice fields that have been flooded with an excess of water. This particular virus can be spread to birds and animals initially. If spread to pigs, it is a signal that it might also be spread to humans. However, this usually only happens when the mosquito population is excessively large. In most cases, the specific strain of mosquitoes carrying the disease prefer to bite and draw blood from animals. When the population grows too large, they also bite humans, thereby infecting them as well. Mosquitoes are most likely to bite during the cool hours of the day, including dawn and dusk. The disease occurs primarily in sub-tropical regions of Southeast Asia, including Indonesia, China, Thailand, Laos, Vietnam, and Cambodia, according to seasonal patterns and rainfall.

Prevention

You only need to worry about preventing JE if you are traveling to an area of risk as there is little to no risk of contracting the disease in the United States. There is a vaccine available; however, many people opt not to get it because it is costly and requires dosages in advance of the time of travel. If possible however, the vaccine can provide immunity against the disease to those who get it. Countries including Korea, China, Japan, Taiwan, and Thailand have prevented epidemics through the use of the vaccine.

There are certain precautions that travelers might take if they want to reduce their risk of contracting the disease. These include covering up with clothing at night, sleeping under a mosquito net, and bringing bug repellent. If possible, stay indoors at peak hours. The less bites you get, the more likely you are to reduce your risk of getting the disease.

It’s always a good idea to monitor your health while you are traveling. In addition, keep up to date on local news; newspapers and radio stations might be able to inform you of areas where outbreaks have occurred. Plan to avoid those areas on your trip if possible. If you suspect you have symptoms, you should contact a health professional immediately.

Treatment

There are no defined treatments for overcoming Japanese encephalitis. Since most cases are mild, it is recommended that patients get a lot of rest and take in fluids. Some pain relievers might be prescribed as needed or in case of fever. In other cases, patients are hospitalized in order to monitor their condition. But treatment is always based on how severe the symptoms are.

In severe cases, treatments include assisted feeding, breathing tubes, and seizure medication. Patients do not need to be quarantined but their condition does require constant observation.