What is Japanese Encephalitis?
Japanese Encephalitis (JE) is a viral disease that infects animals and humans through the bite of infected culex mosquito. Clinically a case of Japanese Encephalitis is described as a case of fever of variable severity, associated with neurological symptoms. It takes 5-15 days after the bite to start developing the symptoms which is called the incubation period. Mild infections may present with only fever and headache or without any apparent symptoms. Around 1 in 200 infections result in serious disease which is marked by sudden onset of high fever, headache, neck stiffness, disorientation, coma, tremors, paralysis, stiffness, or loss of coordination. Even among survivors, the nervous system can suffer lasting damage. JE affects all age groups and especially children under 15 years of age.
What is its cause and how is it spread?
JE is caused by the bite of virus infected Culex mosquitoes. The virus primarily infects animals (especially pigs) and birds, and can be spilled over into humans. Rice fields (also shallow ditches and pools) where mosquitoes breed and accompanied by pig rearing are very common places for transmitting the infections, especially in South East Asia. The virus gets amplified in the blood systems of pigs and birds, but there is no human to human transmission.
What is the diagnosis and management of JE?
A clinical diagnosis is made by a doctor basing on the history and clinical presentation. A definite diagnosis is through laboratory test for JE antigen or antibody in blood (serum) or cerebrospinal fluid. The test is available at District Hospital Dimapur. Only a few of the infected people develop the disease, but there is no definite treatment for JE. Intensive supportive treatment and good nursing can reduce deaths significantly. Case fatality rate ranges from 0.3 to 60%. About 30% of those who survive may suffer from varying ranges of neurological deficits.
How do we prevent JE?
There is a vaccine for JE. However, immunization is not included in the routine immunization and is carried out in select areas as per sero-epidemiological data. The best way to prevent JE is through control of mosquito vectors. Stagnant water bodies should be drained or filled up, and surroundings kept clean and dry. Rice fields can cover wide areas and chemical control may not be feasible. In such situations, water management measures like alternate wetting and drying may be applied to reduce vector population. During pre-monsoon when water bodies are confined to small ponds and tanks, vector control measures can be planned. Personal protection through use of repellents and mosquito nets are effective control measures. Bed nets treated with insecticides are being distributed. Indoor Residual Spray, and fogging in outbreak areas are chemical control measures to reduce vector population. Introduce larvivorous fishes in the paddy fields and other stagnant bodies to eat up the mosquito larva. Larvivorous fishes are available at Urban Malaria Scheme, Chief Medical Officer office, Dimapur. It is discouraged to rear pigs near human dwellings as the virus gets multiplied and amplified in the pigs which can be transmitted to humans. Culex mosquitoes can fly long distances (1-3 kms or more) and it is advised that piggeries be kept 4-5kms from human dwellings. Spread of awareness is important for prevention and also to detect and treat patients early to increase chance of survival and reduce long term mental deficits after recovery.
In case of any illness which resembles the symptoms of JE, visit your nearest health centre/district hospital for sample collection/transportation and treatment of cases. District Control Rooms have been set up in all the District Headquarters for reporting, investigation, and control of outbreaks.
