Japanese Encephalitis (JE) is the leading cause of viral encephalitis in Asia. It is a mosquito-borne flavivirus that is related to dengue, yellow fever and West Nile viruses, usually found in rural and peri-urban settings.
In India, 24 states are endemic for JE, with Uttar Pradesh contributing more than 75% cases in the recent past. During 2014, 10863 Acute Encephalitis Syndrome (AES) including JE cases and 1717 deaths were reported from many parts of the country. Number of cases and deaths of AES have been steadily increasing every year, burdening the health care system and creating confusion, fear and anxiety in the minds of affected communities.
JE outbreaks do not cover large areas and mostly occur in periurban and urban populations, lasting not more than couple of months
Seasonality of illness varies by country, with transmission starting mostly in April/May and lasting till September/October
In some tropical and subtropical areas, incidence peaks during and shortly after rains. Whenever a particular region is temperate with seasonal rain caused by monsoon, it becomes the perfect place for mosquitoes to breed.
JE occurs when the virus is brought into the peridomestic environment by mosquito bridge vectors where there are pigs serving as amplification hosts
Where irrigation permits mosquito breeding through the year, transmission can occur even in the dry season.
• JE virus transmission occurs primarily in rural agricultural areas, often associated with rice production and flooding irrigation
• Patients infected with JE/AES mostly hail from poor socio-economic backgrounds with illiteracy, poverty and other socio-demographic factors; large proportion of afflicted patients are malnourished
• These patients live in settings that have unfavourable environmental conditions and virtually no sanitation facilities
Most JE virus infections are mild (fever and headache) or without apparent symptoms, but approximately 1 in 250 infections result in severe disease characterised by rapid onset of high fever, headache, neck stiffness, disorientation, coma, seizures, spastic paralysis and death
Infections in humans are generally more severe in infants and the elderly and can lead to disorientation, tremors or convulsions (especially in infants), paralysis and coma
The JE virus usually causes disease in horses, donkeys and pigs; other animals too can be infected though typically but they do not show signs of illness
Among patients who develop encephalitis, 20-30% die
Although some symptoms do improve after acute illness, 30-50% survivors continue to have neurologic, cognitive or psychiatric symptoms
There is no specific treatment for JE. Patient management focuses on supportive care and management of complications. Treatment is symptomatic with rest, fluids and use of pain relievers and medication to reduce fever and thereby relieve some symptoms
No specific treatments have been found to benefit patients with JE but hospitalisation for supportive care and close observation is generally required
PHFI/RCZI has just completed a 3-year study (2011-13) in three blocks of Kushinagar, namely Padrauna, Kaptanganj and Khadda, chosen in accordance with JE/AES disease burden
The cross-sectional study: “Identifying Sources, Pathways and Risk Drivers in Ecosystems of JE in an Epidemic Prone North Indian District” was conducted in 12 villages, adopting an EcoHealth approach that studied vector-animal-human interactions along with other environmental, economic, cultural and social factors that influence JE transmission.
The quantitative and qualitative findings will establish greater understanding of the connectedness of economic, cultural, and biological determinants of JEV transmission and disease; and develop recommendations based on comprehensive understanding of disease ecology
JE outbreaks are being reported from previously unknown foci. Further, encephalitis outbreaks of other aetiologies in endemic areas have only added to their complexity. For programme managers, researchers and community health professionals, access to accurate and updated information is key to planning interventions and other relief measures.read more