Australian scientists may have found the secret to eradicating dengue fever, with a lengthy trial in Indonesia drastically reducing the incidence of the mosquito-borne virus.
- Dengue fever has been reduced by 77 per cent in the Indonesian trial areas
- The treatment lasts for years and will save lives
- Researchers say it can be rolled out in other at-risk countries
Researchers at Melbourne’s Monash University working with scientists in Yogyakarta, in Central Java have spent three years infecting local mosquitoes with a bacteria known to prevent them from transmitting the virus to humans.
Known as Wolbachia, the bacteria effectively starves the virus of food.
And as the infected mosquitoesbreed with the wild population, their offspring also have the bacteria.
The first major results from the trial show the incidence of dengue fever in areas where the infected mosquitoes have been released has dropped by 77 per cent.
“In public health, 77 per cent is a really, really big impact,” said Cameron Simmons, who heads the World Mosquito Program at Monash University.
“If this was a vaccine for COVID-19 we’d be delighted with a 77 per cent impact.
The Wolbachia bacteria has persisted at a very high level in the wild population.
“The beauty of this approach is it’s a ‘once and done’ method,” Professor Simmons said.
“After the upfront effort to establish Wolbachia in the mosquito population, it then sustains itself for years without needing more work.”
What is dengue fever and why is this trial so important?
Dengue is the most rapidly spreading mosquito-borne disease in the world.
An estimated 50 million cases occur globally every year.
It can cause bleeding, shock and death.
But other efforts to combat or control the virus have consistently failed.
Mosquitoes are bred in jars as part of the dengue eradication program.(Supplied: World Mosquito Program)
Scientists chose Yogyakarta for the trial because of its population size and because it is one of the cities worst hit by dengue each year in Indonesia, which has one of the world’s highest rates of the disease.
Every year, as many as 8 million Indonesians are infected with the virus, and several thousand die.
“When we started the project, Yogyakarta was number five in the country in terms of dengue cases, so it’s very bad,” Adi Utarini, who led the Indonesian team, said.
“But now they see a remarkable drop. Before there was a lot of local transmission of dengue and that local transmission is no longer there.”
Twenty-four areas of the city took part in the trial.
Twelve were chosen at random to receive the infected mosquitoes.
The rest continued to receive routine dengue control measures, such as regular fogging, which involves spraying chemicals where mosquitoes are known to live and breed.
More than 8,000 participants aged three to 45 from within the trial area who had developed acute fever were then tested.
Scientists then measured the efficacy of the bacteria in reducing the incidence of the disease in treated areas.
The trial could have a global impact
The research first began in Queensland 10 years ago, with lab tests and field studies eventually leading to the state being declared dengue free.
The World Mosquito Program said the results were the most compelling evidence so far the Wolbachia bacteria significantly reduced the incidence of dengue in a densely populated human setting.
Professor Simmons said it had huge ramifications for other parts of South-East Asia and Latin America.
“We’re bravely optimistic our approach can lead to the elimination of dengue in places like Yogyakarta when it’s deployed at the scale of the whole city,” he said.
“Yogyakarta, we think, is just the beginning. There are many other cities in South-East Asia, including the big cities of Bangkok, Jakarta, Ho Chi Minh, and in Latin America Rio de Janeiro, Medellin that get hit by dengue epidemics every two to three years.
“So we think the method is scalable.”
The World Mosquito Program is carrying out similar work in 11 other cities, including trials in Rio de Janeiro.
Professor Simmons acknowledged total eradication of dengue was a longer-term dream, given the time it took to breed and release the infected mosquitos, and the cost-effectiveness of such trials in smaller, rural settings, where dengue was also endemic.
But he is optimistic Wolbachia could hold the key to success.
“I think there’ll be a time when cities and some national regions might be able to declare themselves dengue-free,” he said.