10,000-15,000 people infected with Japanese encephalitis die each year
Proven effective vaccines are best control strategy
Rice paddies, prevalent throughout Southeast Asia, may make for a beautiful landscape, but they are also optimal breeding grounds for mosquitos that carry the JE virus.
Outside of Asia, Japanese encephalitis (JE) is relatively unknown but some four billion people live in areas at risk of the viral disease. JE is especially predominant in the poor rural communities of eight Gavi-eligible countries in Southeast Asia and the Western Pacific.
Often called “brain fever”, JE begins with flu symptoms, progresses to a brain infection and claims the lives of 20 to 30 percent of infected infants and children. According to the World Health Organization (WHO), annual mortality is calculated at 10,000 to 15,000 deaths each year although awareness of the disease is low and the figures may significantly underestimate the impact. In 2005, a devastating outbreak of JE killed nearly 2,000 in India and Nepal, mostly children.
JE’s lifelong toll on its survivors is even less well known. An estimated 30 to 50% of cases result in permanent neurological weaknesses, such as paralysis, recurrent seizures or the inability to speak.
The virus is hosted by wading birds like herons and egrets, which flock to rice paddy fields and by the pigs commonly raised in rural areas. It’s then transmitted to humans by mosquitoes, which breed by the tens of thousands in rice paddies.
JE cannot be transmitted from one person to another.
There is no specific treatment for JE. Prevention of the disease through proven effective and relatively inexpensive vaccines is the best control strategy.
Some Gavi-eligible countries have already initiated JE vaccination programmes, either routine or campaigns. Gavi support will allow countries to reach all population groups at risk through catch up campaigns.
Japanese encephalitis - countries or areas at risk, 2012. Source: World Health Organization
Burden of disease
The disease is endemic with seasonal distribution in parts of China, the Russian Federation’s south-east and South and South-East Asia. All year transmission is observed in tropical climate zones.
The spread of JE in new areas has been correlated with agricultural development and intensive rice cultivation supported by irrigation programmes.