Sarah Dingle reported this story on Tuesday, September 11, 2012 18:26:00

MARK COLVIN: A major clinical trial of the frontrunner in the race for a dengue fever vaccine is showing great promise.



The tropical disease infects up to 100 million people every year, burdens hospitals, kills children, and has no specific treatment.



The drug, developed by a French company, protected against three of the four types of dengue virus in Thai children.



It's not a perfect score but one scientist, currently battling enormous infection rates in Vietnam, says this means there will be a vaccine within a decade.



Sarah Dingle reports.



SARAH DINGLE: For the last 90 years, scientists have been searching for a vaccine for dengue fever.



Some say its name comes from a Swahili phrase for “cramp-like seizure caused by an evil spirit”.



Every year, the World Health Organization estimates between 50 and 100 million people are infected with the virus, and the most vulnerable are children and adolescents.



CAMERON SIMMONS: It's regarded as a neglected tropical disease. The sheer scale of the disease burden in dengue endemic countries is enormous. It's a major public health problem, places enormous strain on often fragile healthcare systems.



SARAH DINGLE: Professor Cameron Simmons is from the Oxford University's clinical research unit based in Vietnam.



In neighbouring Thailand, a major clinical trial of a possible vaccine involving 4,000 primary school aged children has just concluded.



Professor Simmons says the results show it's not a magic bullet, but it is hugely encouraging.



CAMERON SIMMONS: We were optimistic and hopeful that we would see protection against all four dengue viruses. What the study has shown us is that the vaccine seems to offer protection against three and not four of the dengue viruses.



So we've got, there's more research to be done to really try and understand why protection is not against all four but we're heading in the right direction. I think that's the important result.



SARAH DINGLE: There's no clinical difference between the four types of virus; the patient still presents with symptoms like muscle and joint pain, fever, rashes, hair loss, intense headache and extreme fatigue.



The one type of dengue not affected by the vaccine was the most prevalent type in the study's region, and there's concerns that may have dragged down the results.



But the fact that it appears to have worked on the other three has already led to speculation that that could be enough to prevent severe disease.



Professor Simmons isn't so sure.



CAMERON SIMMONS: I think a trial of that a trivalent vaccine could be possible but it's going to need a lot more research to understand from a modelling perspective what a trivalent vaccine might do to the epidemiology of dengue in an endemic setting and also very importantly the cost effectiveness of such a vaccine.



SARAH DINGLE: But Professor Simmons says even for countries like Vietnam, where child mortality rates from dengue fever are relatively low, any hope is welcome.



CAMERON SIMMONS: Yeah, the disease burden is enormous here; 10-15 per cent of the hospitalised patients in the hospital that I work in are dengue cases.



So it's one of the most important causes of hospitalisation for children. So the scale of the disease burden is enormous, public health importance is very large.



One dengue virus infection actually predisposes you to a more severe infection a second time around and so it's a complicated disease in that fashion.



SARAH DINGLE: A third stage of the trial involving 30,000 people from South-East Asia and Latin America is due to deliver results in 2014.



Professor Simmons says he's hoping for a fully fledged dengue virus vaccine within five to 10 years.



MARK COLVIN: Sarah Dingle.