The Aedes aegypti mosquito, carrier of dengue.
The Aedes aegypti mosquito, carrier of dengue.

25 August 2011

Leading scientific journal Nature has today published two papers describing the results of biological control field trials where wild mosquito populations were manipulated to suppress dengue virus transmission.

The results are the work of the Eliminate Dengue program, an international collaboration of scientists located in research institutes in Australia, Vietnam, Thailand, the USA and Brazil and led by Professor Scott O'Neill, former head of the School of Biological Sciences at UQ who holds a research professorship (part-time) at the Institute for Molecular Bioscience.

Professor O'Neill is now Dean of Science at Monash University, Melbourne.

The program is developing a new approach to reduce the global burden of dengue fever.

Primary Investigators in Australia and co-authors on the published papers include Professor Ary Hoffmann, The University of Melbourne and Professor Scott Ritchie, James Cook University, Cairns.

The World Health Organisation ranks dengue fever as the most important mosquito-borne viral disease in the world, with an estimated 2.5 billion people living in dengue transmission areas and more than 50 million cases annually.

UQ Deputy Vice-Chancellor (Research) Professor Max Lu congratulated Professor O'Neill and his team on the success of the trials.

"This results from the research conducted by Professor O'Neill and his team since he joined UQ in 2001 as Professor and Head of the then School of Life Sciences," he said.

Professor O'Neill said current control methods, largely based around insecticide use, were failing to stop the global dengue problem.

“We hope to develop a new control method that could provide a practical, sustainable and cost effective approach to dengue suppression around the world,” Professor O'Neill said.

The program's unique method is Wolbachia, a natural bacterium already present in up to 70 percent of all insect species and known to reduce mosquito susceptibility to dengue and other viruses.

The program team successfully introduced Wolbachia into wild populations of the mosquito that transmits dengue, Aedes aegypti, as a way to reduce the ability of these mosquitoes to transmit the virus between people.

“Years of laboratory experiments had shown that we could introduce Wolbachia into the mosquito in the lab, where it then passed from one generation to the next in the mosquito egg," Professor O'Neill said.

"The papers published today describe: the successful establishment of a particularly promising Wolbachia strain within the dengue mosquito in the lab; its subsequent ability to reduce dengue transmission potential of the mosquito; and also the successful introduction of the same Wolbachia strain into wild mosquito populations in Australia.”

In January this year, with overwhelming support from the community and regulatory approval from the Australian Pesticides and Veterinary Medicines Authority (APVMA), mosquitoes carrying Wolbachia were released in the Cairns suburbs of Yorkeys Knob and Gordonvale, in Queensland, Australia. Within a 3-month period Wolbachia had successfully invaded the local mosquito populations.

“The field trial involved releasing Wolbachia- mosquitoes every week for 10 weeks," Professor O'Neill said.

"Five weeks after the final release it was determined that 100% of the mosquitoes at Yorkeys Knob carried Wolbachia and 90% in Gordonvale. That was a great day.

“These findings tell us that Wolbachia-based strategies are practical to implement and might hold the key to a new sustainable approach to dengue control, an approach that should be particularly suited to large cities of the developing world where conventional control with insecticides is largely ineffective and prohibitively expensive.

"The method should also be compatible with vaccines as they become available.”

The program plans to undertake further trials in Cairns over the coming wet season to test how well Wolbachia will spread across less contained areas than the initial trial sites.

Following the success of the first Australian field trial regulatory approval is currently being sought for trials in Thailand, Vietnam, Brazil and Indonesia that will directly determine the effectiveness of the method in reducing dengue disease in human populations.

The research program is supported by the following organisations:

  • The Foundation for the National Institutes of Health through the Grand Challenges in Global Health Initiative of the Bill and Melinda Gates Foundation
  • The National and International Research Alliances Program of the Queensland State Government
  • The National Health and Medical Research Council of Australia
  • The Climate Health Cluster of the CSIRO Flagship Collaboration Fund

Contact:

Helen Cook, Communications Officer - 07 4040 2503 or 0439 878 070

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