Wolbachia trial dramatically reduces dengue cases

A recently released results of a randomized controlled trial published in the New England Journal of Medicine show that the incidence of dengue was reduced by 77% in areas of Yogyakarta, Indonesia where mosquitoes with Wolbachia were released. Dengue cases requiring hospitalization were reduced by 86% in the Wolbachia-treated areas. Efficacy was equivalent for all four serotypes of dengue.

The trial, “Applying Wolbachia to Eliminate Dengue (AWED)”, was conducted by the World Mosquito Program from Monash University with its Indonesia partners Gadjah Mada University and donors the Tahija Foundation. It aimed to test whether the introduction of Wolbachia (wMel) into the local Aedes aegypti mosquito population, through the release of Wolbachia-infected mosquitoes, would reduce the incidence of virologically-confirmed dengue amongst 3-to-45 year olds living in Yogyakarta, Indonesia.

More than three years after completion of mosquito releases, Wolbachia remains at a very high level in the local mosquito population. Since the trial, the Wolbachia method has been implemented across the entire city of Yogyakarta and releases have commenced into neighbouring districts, to cover a population of 2.5 million people.

The result is consistent with previous trials of the Wolbachia method, which show long-term reduction in dengue incidence once Wolbachia is sustained within the local mosquito population.^[1] Studies also show the Wolbachia method to be effective in also preventing the transmission of Zika, chikungunya, yellow fever and other vector-borne diseases.

Dengue is the most rapidly spreading mosquito-borne disease in the world, with more than 50 million cases occur globally every year^[2]. Co-Principal Investigator, Prof. Cameron Simmons from Monash University believes that these results showcase the significant impact the Wolbachia method can have in reducing dengue in urban populations. “This result demonstrates what an exciting breakthrough Wolbachia can be – a safe, durable and efficacious new product class for dengue control is just what the global community needs,” he said.

World Mosquito Program Director, Prof. Scott O’Neill said, “This is the result we’ve been waiting for – evidence that our Wolbachia method is safe, sustainable and dramatically reduces incidence of dengue. It gives us great confidence in the positive impact this method will have worldwide when provided to communities at risk of these mosquito-transmitted diseases.”

The potential for this Wolbachia method to be deployed across communities worldwide has been acknowledged by the World Health Organisation, whose Vector Control Advisory Group declared “Wolbachia demonstrates public health value against dengue” recently.^[3]

The risk of dengue fever infection in the Philippines is nationwide. According to a recent Singapore study by ValueChampion, the Philippines is considered a nation at most risk from dengue across 12 countries in Southeast Asia. Moreover, the Philippines Department of Health (DOH) reported more than 59,000 cases of dengue fever in 2020 while the DOH declared a national dengue epidemic on 2019 after more than 400,000 people were infected with the virus with over 1,000 deaths recorded

Dr. Jacqueline Deen MSc, a paediatric infectious disease specialist and a professor at the University of the Philippines – Manila, said the trial assessing the protective efficacy of Wolbachia-infected Aedes aegypti on dengue incidence and hospitalizations is well conducted and builds on years of hard work and several studies. “The latest results provide hope for the improved control of dengue in the future”, she added. An estimated 1,107 people have died of dengue during the 2019 Philippine Dengue epidemic, where almost half were children between five and nine years of age.

These results have significant implications for 40% of the world’s population at risk of dengue. The World Mosquito Program aims to work in partnership with national and local governments, corporate citizenship programs, charitable organizations and non-governmental organizations to expand Wolbachia protection worldwide. To date, the World Mosquito Program has supported releases in 11 countries in Asia, Australia, Latin America and the Pacific with an estimated 6.8 million people now benefiting from Wolbachia coverage.

In conjunction with the publication of the trial results in the New England Journal of Medicine, the World Mosquito Program released a video [LINKED] and animated short [LINKED], describing the trial, its results and the implications for combating dengue in the future.

^[1]Peter A Ryan et al., September 2019, Gates Open Research  https://www.worldmosquitoprogram.org/en/learn/scientific-publications/establishment-wmel-wolbachia-aedes-aegypti-mosquitoes-and

^[2]  Global Burden of Disease study, 2019

^[3] https://www.who.int/vector-control/vcag/meeting-reports/en/