Bill Gates boosts fight against virus that threatens three billion

Microsoft billionaire Bill Gates has donated £27m (£16m; €22m) to step up the fight against a debilitating virus that kills one in three of its victims.

The Bill and Melinda Gates Foundation this week announced funding for a five year programme to combat Japanese encephalitis, the leading cause of viral encephalitis in Asia.

Almost half of all cases of the disease, a mosquito borne flavavirus result in long term disability, including paralysis, seizures, and mental disability.

A third of victims, mainly children aged under 15, die. The condition is untreatable but can be prevented through vaccination.

The Children's Vaccination Project at the Program for Appropriate Technology in Health (PATH), in Seattle, Washington, will use the money to accelerate development of an improved vaccine and bolster disease surveillance.

Project director Dr Julie Jacobson said it was “an absolute travesty” that so little had been done to protect people against a virus that now threatened up to three billion people in Asia.

Dr Jacobson said vaccine development had “languished on the back burner” because Japanese encephalitis was largely confined to the developing world.

“The vaccine used at the moment is expensive and in short supply. There is no economic incentive for manufacturers to develop it,” said Dr Jacobson.

She said the disease was frequently mistaken for other diseases as diagnostic tests were not readily available so public surveillance had to be improved.

The centre will work with the Global Alliance for Vaccines and Immunisation to help countries incorporate the adopted vaccine into routine immunisation campaigns. It will also try to convince manufacturers there is a market for their vaccines in affected countries.

The current vaccine is derived from mouse brain and requires one mouse to produce each dose. Three doses are needed to gain 90% efficacy, and boosters are given every three years.

China produces and uses a live attenuated vaccine that is yet to be approved by the World Health Organization because of concerns about the manufacturing process. A recombinant vaccine using a strain of the yellow fever virus was successfully tested in animals and humans, but the manufacturers have yet to commit to production.

Some 30 000 to 50 000 cases of Japanese encephalitis are reported each year, resulting in 10 000 to 15 000 deaths.

The virus is prevalent in East Asia, South Asia, and South East Asia. Recent large outbreaks in India and Nepal have raised serious concerns that the disease is spreading more rapidly. It is most commonly spread by the Culex tritaeniorhynchus mosquito, which breeds in flooded rice fields, marshes and standing water pools. Pigs and wild birds are the main virus hosts.