Dengue fever cases cut by 77% and hospitalisations by 86% in groundbreaking study

ITV News Correspondent Rebecca Barry has the details of the 'major step forward' in tackling Dengue

Dengue fever cases have been cut by 77% and hospitalisations by 86% in a trial which has marked a "major step forward" in tackling, what the World Health Organization (WHO) has described as, one of the top 10 threats to global health.

The viral illness, also known as "break bone fever" because it causes severe muscle and bone pain, is transmitted by mosquitoes in tropical climates and can cause death and overwhelm hospitals.

Around 390 million people each year are infected with the disease, 25,000 of who die.

In a groundbreaking study, scientists infected Aedes aegypti mosquitoes which can pass dengue viruses on to humans with a bacteria called Wolbachia.

Not only does Wolbachia prevent mosquitoes from being infected with dengue viruses it also spreads very quickly and does not harm its host.

The bacteria compete for resources and make it much harder for dengue virus to replicate, so the mosquito is less likely to cause an infection when it bites again.

Scientists divided a 10square mile section of Yogyakarta City, on the island of Java in Indonesia, into 24 districts.

The province consistently ranks in the top 10 in Indonesia for yearly dengue rates.

Measures such as fumigation only prevent dengue fever outbreaks in the short-term. Credit: AP

In a random selection of 12 districts they released Aedes aegypti mosquitoes infected with Wolbachia bacteria, while in the other 12 they carried on with routine dengue control measures, so essentially carried on as before.

The trial used five million mosquito eggs infected with Wolbachia.

Eggs were placed in buckets of water in the city every two weeks and the process of building up an infected population of mosquitoes took nine months.

People who consented to be part of the study and who developed a fever during the time the trial took place were then tested for dengue.

All four dengue virus serotypes (version) were detected among trial participants and efficacy was similar across them all. 

Such was the impact of Wolbachia on dengue rates that after the study was completed, mosquitoes carrying the bacteria were released across the rest of central Yogykarta - an area home to 400,000 people.

It's now being expanded into surrounding provinces, with the aim of protecting four million people by the end of next year. It is estimated that this could prevent an estimated 10,000 dengue infections annually.

The World Mosquito Programme hopes that in years to come, this could result in local elimination of dengue viruses.