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Bacterium trials could stop spread of dengue

Update: June, 13/2013 - 09:58

by Gia Loc

HCM CITY (VNS)— The Wolbachia bacterium, which is being used in Viet Nam on a trial basis, could become an effective bio-control strategy to control not only dengue fever but also other insect-borne illnesses, according to expert.

Professor Scott O'Neill, head of the Eliminate Dengue team and dean of science at Australia's Monash University, said the transmission of dengue fever between humans could be stopped by the use of Wolbachia-infected mosquitoes.

O'Neill spoke at a seminar on Monday held by the Australian Embassy and Consulate-General on the occasion of the 40th anniversary of diplomatic relations between Viet Nam and Australia.

Begun in 2005, the Eliminate Dengue programme is being carried out in Australia, Brazil, China, Indonesia and Viet Nam.

It is funded by the Foundation for the National Institutes of Health through the Bill & Melinda Gates Foundation's Grand Challenges in Global Health Initiative.

O'Neill is the programme leader for the research programme, which is an international collaboration involving experts from around the world.

The Wolbachia bacterium occurs naturally in up to 70 per cent of all insect species, but not in the dengue-carrying mosquito Aedes aegypti. It is passed from one generation to the next through insects' eggs.

"In our research, we have demonstrated that we can transfer the bacterium from the fruit fly into the Aedes aegypti mosquitoes, and by doing this, also demonstrate that when Wolbachia is present, the ability to transmit dengue viruses is reduced," O'Neill said.

The first outbreak of dengue fever in Viet Nam was recorded in 1963.

Over the past 10 years, it has increased significantly due to changes in household water-supply infrastructure, urbanisation and an increasingly mobile population.

Current control methods have focused on community-education campaigns and response to dengue outbreaks through insecticide spraying in affected areas.

The Eliminate Dengue Viet Nam programme began in 2006 with oversight by the Ministry of Health.

In 2007, Tri Nguyen Island of central Khanh Hoa Province was chosen as the first trial site in Viet Nam, but only preliminary work has been done since then.


In April, the team for Eliminate Dengue deployed the strongest dengue-blocking Wolbachia strain-wMelPop- by releasing resistant insects that had been infected with the Wolbachia bacterium.

Within four weeks, the number of Wolbachia-infected mosquitoes on the island accounted for 36 per cent of the total number, O'Neill said.

"This is a positive result," he said, adding that if the Wolbachia strain were present in all mosquitoes on the island, dengue transmission would be disrupted.

Trials at other sites in Viet Nam will be conducted if the one carried out inn Khanh Hoa Province is successful.

O'Neill said that if all the trials worldwide were successful, this method would help reduce the risk of dengue fever for the 2.5 billion people that live in those areas. — VNS

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