Dengue Field Trial Update · aegypti mosquitoes in these suburbs ... encourage you to register your...
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First hurdle reached – I am delighted to report, on behalf of the Eliminate Dengue team, that the first field trials of our method to control dengue, carried out in Yorkeys Knob and Gordonvale earlier this year, successfully achieved what we set out to do, with the results of the work recently published in the prestigious scientific journal Nature (25th August 2011). Our goal for this first field trial was to see if we could introduce Wolbachia into the wild population of Aedes aegypti mosquitoes in these suburbs and if we could introduce it, within the course of the wet season, then monitor how well it would spread. From early January mosquitoes carrying Wolbachia were released once a week for 10-weeks from properties where residents had given prior permission. One week after the first release mosquito egg traps were deployed in volunteer properties and monitored for Wolbachia infection. Five weeks after the final (10th) release our monitoring recorded 100% of the Aedes aegypti mosquitoes in Yorkeys Knob carried Wolbachia and 90% in Gordonvale – as shown on the graphs (right). So what does this mean? – Years of laboratory work have shown that when Wolbachia is introduced into mosquitoes they become more resistant to getting infected with the dengue virus. If mosquitoes don’t become infected with dengue, they can’t transmit the virus between people. While we have good lab results the next challenge for us was to determine if we could actually deploy Wolbachia into the field. What the results from these first field trials tell us is that Wolbachia- based strategies can be deployed as a practical approach to dengue suppression. But before we get too excited we still have a lot of work to do. We still need to determine how well Wolbachia will persist in the mosquito population, how easily it will spread and how big an impact it might have on dengue transmission under field conditions – which are often quite different than lab conditions. The next hurdle – The Cairns field team is continuing to monitor traps in and around Gordonvale and Yorkeys Knob to see if the Wolbachia has stayed in the mosquito population over the dry season. If this is the case, we will then use these sites as ‘nurserys’ to provide eggs that carry Wolbachia – since it is passed from mother to offspring through the eggs – for further field trial sites in Cairns over the coming wet season. The project team will soon be engaging with residents and other stakeholders in further Cairns suburbs and with the support of these communities begin planning the next trials. At the same time new trials are beginning in neighbouring countries where dengue is a much bigger problem than Cairns. The main purpose of these trials will be to directly measure the impact of the method on reducing dengue cases. Dengue Field Trial Update By Professor Scott O’Neill, Program Leader 25th August 2011 E: [email protected] www.eliminatedengue.com Ph: 1800 811 054 % Aedes aegypti mosquitoes found in Yorkeys Knob (13 th April) and Gordonvale (18 th April) with Wolbachia 100% 0% 19th Jan: 20% 16th Feb: 38% 16th Mar: 76% 31st Mar: 98% 100% 1 3 s t A p r 2 0 1 1 100% 50% 0% 19th Jan: 20% 21st Feb: 49% 21st Mar: 68% 5th Apr: 77% 90% 1 8 t h A p r 2 0 1 1 Mosquitoes with Wolbachia Mosquitoes without Wolbachia Your help – To all those residents in Yorkeys Knob and Gordonvale, and neighbouring suburbs who have helped us with the first field trials, on behalf of the Eliminate Dengue team around the world, may I say ‘thank you’ – but not ‘good- bye’, we need your continued support, and the team will be in-touch soon. To all other residents in Cairns who would like to assist in our research we encourage you to register your support by sending your residential or business details to [email protected] or phone us with any questions or concerns on 1800 811 054. We look forward to hearing from you. Gordonvale Yorkeys Knob
Transcript of Dengue Field Trial Update · aegypti mosquitoes in these suburbs ... encourage you to register your...
First hurdle reached – I am delighted to report, on behalf of the Eliminate Dengue team, that the first field trials of our method to control dengue, carried out in Yorkeys Knob and Gordonvale earlier this year, successfully achieved what we set out to do, with the results of the work recently published in the prestigious scientific journal Nature (25th August 2011).
Our goal for this first field trial was to see if we could introduce Wolbachia into the wild population of Aedes aegypti mosquitoes in these suburbs and if we could introduce it, within the course of the wet season, then monitor how well it would spread.
From early January mosquitoes carrying Wolbachia were released once a week for 10-weeks from properties where residents had given prior permission. One week after the first release mosquito egg traps were deployed in volunteer properties and monitored for Wolbachia infection. Five weeks after the final (10th) release our monitoring recorded 100% of the Aedes aegypti mosquitoes in Yorkeys Knob carried Wolbachia and 90% in Gordonvale – as shown on the graphs (right).
So what does this mean? – Years of laboratory work have shown that when Wolbachia is introduced into mosquitoes they become more resistant to getting infected with the dengue virus. If mosquitoes don’t become infected with dengue, they can’t transmit the virus between people. While we have good lab results the next challenge for us was to determine if we could actually deploy Wolbachia into the field.
What the results from these first field trials tell us is that Wolbachia-based strategies can be deployed
as a practical approach to dengue suppression. But before we get too excited we still have a lot of work to do. We still need to determine how well Wolbachia will persist in the mosquito population, how easily it will spread and how big an impact it might have on dengue transmission under field conditions – which are often quite different than lab conditions.
The next hurdle – The Cairns field team is continuing to monitor traps in and around Gordonvale and Yorkeys Knob to see if the Wolbachia has stayed in the mosquito population over the dry season. If this is the case, we will then use these sites as ‘nurserys’ to provide eggs that carry Wolbachia – since it is passed from mother to offspring through the eggs – for further field trial sites in Cairns over the coming wet season.
The project team will soon be engaging with residents and other stakeholders in further Cairns suburbs and with the support of these communities begin planning the next trials. At the same time new trials are beginning in neighbouring countries where dengue is a much bigger problem than Cairns. The main purpose of these trials will be to directly measure the impact of the method on reducing dengue cases.
Dengue Field Trial UpdateBy Professor Scott O’Neill, Program Leader 25th August 2011
www.eliminatedengue.com Ph: 1800 811 054
% Aedes aegypti mosquitoes found in Yorkeys Knob (13th April) and
Gordonvale (18th April) with Wolbachia
100%
0%
19th Jan: 20%
16th Feb: 38%
16th Mar: 76%
31st Mar: 98%100%
13st Apr
2011
100%
50%
0%
19th Jan: 20%
21st Feb: 49%
21st Mar: 68%
5th Apr: 77%
90%
18th A
pr 20
11
Mosquitoes with Wolbachia
Mosquitoes without Wolbachia
Your help – To all those residents in Yorkeys Knob and Gordonvale, and neighbouring suburbs who have helped us with the first field trials, on behalf of the Eliminate Dengue team around the world, may I say ‘thank you’ – but not ‘good-bye’, we need your continued support, and the team will be in-touch soon.
To all other residents in Cairns who would like to assist in our research we encourage you to register your support by sending your residential or business details to [email protected] or phone us with any questions or concerns on 1800 811 054.
We look forward to hearing from you.
Gordonvale
Yorkeys Knob
What is Dengue fever? – Dengue is caused by a group of closely related viruses that are transmitted between people by the Aedes aegypti mosquito.
The World Health Organisation (WHO) ranks dengue as the most important mosquito-borne viral disease in the world occurring in over 100 countries with an estimated 50-100 million cases each year. Currently there is no cure for dengue or effective way to control the spread of the virus, other than attempting to reduce breeding sites and applying insecticides.
The Eliminate Dengue Program – The program was established in 2005, and is an international collaborating effort involving research institutions in Australia, Vietnam, Thailand, the USA and Brazil.
The program’s aim is to stop the Aedes aegypti mosquito from passing dengue virus between humans and hopes to do this by introducing a naturallyoccurring bacterium called Wolbachia into the existing wild mosquito population. The effect of Wolbachia is to reduce dengue virus transmission by the mosquito to people.
Program Funding – The program is funded primarily by the Foundation for the National Institutes of Health through the Bill & Melinda Gates Foundation’s Grand Challenges in Global Health Initiative.
Funding for the Cairns field trials has also been provided by the Queensland Government through the ‘National and International Research Alliances Program’ and the Australian Government through the ‘National Health and Medical Research Council’.
Q1: What is Wolbachia?
A: Wolbachia are bacteria that only live inside insect cells. This bacterium occurs naturally in up to 70 per cent of all insect species, including well-known insects like the Cairns Birdwing Butterfly, (pictured below) as well as many mosquito species that bite people but do not transmit disease.
Q2: How were the field trials regulated?
A: The Cairns trial underwent rigorous lab testing and received regulatory approval (APVMA permit 12311) from the Australian Government through the Australian Pesticides and Veterinary Medicines Authority (APVMA). The Eliminate Dengue program also commissioned an independent risk assessment by the CSIRO who gave it the lowest possible rating of ‘negligible’ risk to people and the environment. Before any further trials are held in Cairns the program will seek an additional permit from the APVMA.
Q3: Are Yorkeys Knob and Gordonvale now dengue-proofed?
A: It is hoped that all emerging Aedes aegypti mosquitoes in Yorkeys Knob and Gordonvale will have Wolbachia and this will make it difficult for dengue, if it is brought into these suburbs, to be transmitted between people.
However this method will not prevent dengue from occurring in residents that might be bitten by mosquitoes outside of these areas. We expect that the presence of Wolbachia in the local mosquitoes will make it harder for local transmission to occur in these suburbs. The full extent of the protection being provided is still to be measured. Residents should continue to protect themselves from all mosquito bites and carry out dengue protection as they normally would.
Q4: Which suburbs might the trials go to next?
A: In our second round of trials we plan to test how well Wolbachia may spread across a more populated and less contained area, unlike the contained areas of Yorkeys Knob and Gordonvale. Over the coming months the project team will be engaging with the community in Cairns suburbs where dengue outbreaks have previously occurred and with the support of residents and businesses we would hope to commence the second trial in two or three identified areas at the beginning of the next wet season.
Q5: What do the Cairns field trial results mean to the future of the Eliminate Dengue Program?
A: If further trials prove successful in Australia and Asia the Eliminate Dengue method would be a sustainable approach to dengue control which could benefit an estimated 2.5 billion people currently living in dengue transmission areas.
Q6: How can the Cairns community help?
Call the Cairns office on freephone 1800 811 054 to register your support or email your details to [email protected]
For more ‘Frequently Asked Questions’ (FAQs) go to www.eliminatedengue.com or to put a question to the team email [email protected]
Visit the Cairns project office at: Suite 11/36 Grafton St, Cairns. Open Monday - Friday 8.30am – 5.00pm. Visit the program website www.eliminatedengue.com for progress updates
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