April 2012
March results reach 68% Wolbachia infection in Machans Beach and 76% in Babinda
Wolbachia levels continue to rise in Machans Beach with the third monthly measurement showing that 68% of all Aedes aegypti mosquitoes are now carrying the bacteria. Dengue Field Trial Update 11 - Machans Beach [PDF] and Dengue Field Trial Update 12 - Babinda [PDF]
March 2012
Wolbachia read remains high in Babinda and increases in Machans Beach
The second monthly read for Wolbachia-infected Aedes aegypti shows an increase in Machans Beach to 60% with the measurement in Babinda remaining high at 73%. Dengue Field Trial Update 9 - Machans Beach [PDF] and Dengue Field Trial Update 10 - Babinda [PDF]
February 2012
First results for wMelPop
After two weeks of releases in Machans Beach and three weeks in Babinda our first data results are in. Both results have exceeded our expectations with Machans Beach recording 49% Wolbachia-infected Aedes aegypti on 18th January and Babinda recording 75% on 23rd January. Dengue Field Trial Update 7 - Machans Beach [PDF] and Dengue Field Trial Update 8 - Babinda [PDF]
November 2011
Wolbachia after the winter and further trials in 2012
With Wolbachia levels maintained over a very dry winter we are now focusing on further trials for the coming wet season in Cairns with a different strain of Wolbachia. Dengue Field Trial Update 5 [PDF]
25 August 2011
Wolbachia levels reach 100% with the results published in scientifc journal Nature
Five weeks after the last release Wolbachia levels reached 100% in Yorkeys Knob and 90% in Gordonvale. Dengue Field Trial Update 4 with FAQs [PDF]
14 April 2011
Wolbachia levels reach 76% in March
Wolbachia levels continue to increase with overall frequency measurements of 76% recorded for Yorkeys Knob and 68% for Gordonvale in March. Dengue Field Trial Update 3 with Wolbachia breakdown by block [PDF]
17 March 2011
Continuing on track, February results reach 49%
Our second measurement to see how many mosquitoes in the two trial sites of Yorkeys Knob and Gordonvale have Wolbachia has now come in. Monitoring traps collected on 21st February from Gordonvale showed that overall 49% of Aedes aegypti mosquitoes contained Wolbachia. The results for Yorkeys Knob, from traps collected on 16th February, showed a slightly lower rate of 38%. Dengue Field Trial Update 2 [PDF]
15 February 2011
Field trial first results, 20% in January
Since the first release of Wolbachia infected Aedes aegypti mosquitoes on 4th January the project team has been releasing weekly at the trial sites in Yorkeys Knob and Gordonvale. At the same time as releasing we are setting small traps in yards within the trial sites, that mosquitoes lay eggs in. These traps are monitored to see how many mosquitoes in the two suburbs have Wolbachia.
Our first measurement has just come in from mosquito eggs collected soon after the experiment started in January. These results show that roughly 20% of the Aedes aegypti mosquitoes in both suburbs at that time (19th January) had Wolbachia, whereas none did when the trial began. Dengue Field Trial Update [pdf]
4 January 2011
Field trials commence in far north Queensland
On 4th January the Eliminate Dengue project commenced a 12-week field trial in the Cairns suburbs of Yorkeys Knob and Gordonvale. With the support of residents in the suburbs approximately 40 Wolbachia mosquitoes, produced at James Cook University, Cairns will be released from every fourth house over the trial period.
The team will monitor how well the Wolbachia is spreading into the wild mosquito population through small traps placed in selected yards. Cairns residents will be provided with regular updates on how the research is progressing with results distributed through the project newsletter, local media articles, presentations, meetings and this website.
Professor Scott O'Neill releases the first Wolbachia Aedes aegypti at Yorkeys Knob, 4th January 2011.
September 2010
Regulatory approval to commence field trials in far north Queensland
Following rigorous assessment of the project’s safety to humans and the environment, approval from the Federal Government’s Australian Pesticides and Veterinary Medicines Authority (APVMA) has been given to commence field trials of the control method in the communities of Yorkeys Knob and Gordonvale, near Cairns in far north Queensland.The first field tests will commence in January 2011 and aim to determine how well Wolbachia spreads into mosquito populations under different release conditions and whether the anti-dengue properties are evident in wild mosquito populations. Download the updated project brochure [pdf]
May 2010
Wolbachia is common in our environment
Wolbachia occurs naturally in the environment living inside the cells of many insect species and being passed from one generation to the next inside the insect egg. If you would like to see some examples of common Australian insects that naturally contain Wolbachia click here
December 2009
A Wolbachia Symbiont in Aedes aegypti limits infection with Dengue, Chikungunya and Plasmodium
In a recent scientific breakthrough published in the journal Cell, our team has shown that Wolbachia infection directly inhibits the ability of a range of human pathogens to infect Aedes aegypti. This Wolbachia-mediated pathogen interference effect will work synergistically with the life- shortening strategy proposed previously to provide a powerful approach for the control of insect transmitted diseases - a very exciting discovery. [PDF] [supplemental data] [Video Summary]
October 2009
Other science results supporting our approach
An interesting paper was published in Science in October 2009 that has bearing on our program. Dr Steve Sinkins from Oxford University used Wolbachia infected Aedes aegypti to show that they were resistant to the nematode that causes lymphatic filariasis. The idea that Wolbachia infected mosquitoes are resistant to a range of human pathogens will be useful to control a range of diseases in addition to dengue. [PDF].
17-18 September 2009
Cairns Risk Assessment Workshop on Release of wMelpop Aedes aegypti
A risk assessment of the proposed release of Ae. aegypti carrying wMelpop Wolbachia is being undertaken by the CSIRO. They held an expert opinion workshop in Cairns in September with the aim of combining scientific and community opinion on the likelihood of different hazards occuring in the project. This data is being modelled to evaluate the risk of a pilot release and the risk that wMelpop Ae. aegypti will increase the likelihood of harm beyond that currently being experienced.
August 2009
Wolbachia infection reduces feeding ability in the dengue mosquito
We have shown that the blood feeding behaviour of Ae. aegypti is altered by the presence of Wolbachia infection. As the Wolbachia infected mosquitoes age, it becomes more and more difficult for them to obtain blood from a human host. When these mosquitoes are examined closely it appears that their proboscis (mouthpart structure) does not function correctly. Instead of successfully inserting their stylet into the skin, the entire proboscis bends in half when the infected female mosquito presses it against human skin. This change in feeding may further reduce the time window of a female mosquito's life when she could transmit dengue virus. (See Project Publications page publication link.) Video
August 2009
Cytoplasmic incompatibility (CI) in populations with overlapping generations - the mathematics of the project
CI-causing infections produce a frequency-dependent reproductive advantage for infected females. However, many such infections impose fitness costs, such as life-shortening, that lead to unstable equilibrium frequencies below which the infections tend to be eliminated. An idealized model of overlapping generations with age-independent parameters produces a simple expression showing how the unstable point depends on the population growth rate, the intensity of CI, and the infection's effects on development time, longevity and fecundity. (See Project Publications page publication link.)
July 2009
Community Engagement - ESC Grant
Recently our community engagement activities have expanded in Vietnam through the award of an additional grant from the University of Toronto that is focused on our Ethical, Social and Commercial activities in this country. The first introduction workshop was held in Hanoi on Tuesday 28 July to educate senior Ministry of Health officials on the concepts and future planning of the Wolbachia project.
June 2009
Regulatory Approval
We have begun the process of obtaining Australian government regulatory approval for an open field test of the Wolbachia method. This has involved the commissioning of an independent and comprehensive risk assessment report by CSIRO in Australia. This risk assessment will form the basis of our submission to State and Federal government agencies for regulatory approval to begin field testing of the method.
6 February 2009
Characterization of the Aedes aegypti population on an island field site in Vietnam
We have now assessed the long-term seasonal abundance and spatial distribution of Ae. aegypti as a precursor to the development of a vector control strategy based on the release of wMelPop transinfected mosquitoes. For the small island field site of approximately 600 households, we estimated an upper Ae. aegypti population size of 26,000 adult female mosquitoes. Therefore, for a Wolbachia-based intervention, we envisage that multiple, broad scale releases from numerous locations in the village (as opposed to a few, focal releases) will most likely be required – this will counteract any spatial heterogeneity, dampen the effect of transient key premises and enhance movement rates of Wolbachia.
10 January 2009
Official launch of GCGH field cage in Nha Trang, central Vietnam
A purpose built GCGH field cage for studying the survivorship of Aedes aegypti under field conditions in Vietnam was officially launched during a field visit by GCGH project partners. The field cage was specifically designed to recreate the peri-domestic environment in which Aedes aegypti mosquitoes live, and includes a two bedroom house typical of those in central Vietnam, and also water storage jars which are key breeding sites for Aedes aegypti mosquitoes. Current experiments aim to validate age grading methodologies on local strains of Aedes aegypti, and then use these tools to define mosquito longevity under field conditions.
2 January 2009
Life-shortening Wolbachia transferred to Aedes aegypti
Research describing the stable introduction of a life-shortening Wolbachia infection into the primary dengue vector Aedes aegypti was published in this week’s edition of Science (2 January 2009). This milestone piece of work conducted by researchers at The University of Queensland used embryonic microinjection to successfully generate two lines of Aedes aegypti each carrying heritable life-shortening Wolbachia bacteria. The Wolbachia infection halves mosquito lifespan under laboratory conditions, and induces strong cytoplasmic incompatibility needed for the bacteria to spread into natural populations. These two infected mosquito lines are currently being mated in the laboratory to a genetically diverse Aedes aegypti populations from Australia and Vietnam in preparation for their use in contained field cage trials to further evaluate the efficacy of our proposed strategy.
12 November 2008
Application of popcorn Wolbachia for the control of other diseases
Studies are underway to determine if life-shortening Wolbachia strains can be introduced into Anopheles farauti, a mosquito vector of malaria. This work will allow us to evaluate this strategy for use against malaria, a major source of mortality and morbidity throughout the tropics. Initial experiments are being carried out to determine if life-shortening Wolbachia can co-exist with other strains of Wolbachia in Drosophila flies. These studies will help determine the likely outcome of introducing life-shortening Wolbachia into mosquito species that are naturally infected with other strains of Wolbachia.
3 November 2008
How does Wolbachia cause life-shortening in insects
In order to identify which gene or genes are responsible for the life-shortening induced by popcorn Wolbachia in mosquitoes, we have now sequenced the complete genome of the popcorn Wolbachia using next generation sequencing technologies. This sequence is now being compared to other Wolbachia genomes currently available, in particular those of related strains which are not able to reduce insect lifespan. This comparative analysis will allow the identification of the genetic basis of life-shortening.
22 October 2008
Wolbachia shown to directly interfere with RNA virus replication in insects
In a new discovery published in Science in October 2008 22(5902):702 it is shown that the presence of Wolbachia in fruit flies leads to a reduction in viral replication when flies are challenged with pathogenic RNA viruses. This exciting result might have implications for our project. If Wolbachia infections in mosquitoes result in reduced replication rates of dengue viruses, this should act to increase the extrinsic incubation period, and act synergistically with the proposed life-shortening strategy. Experiments with mosquitoes are currently underway to see if the results generalize to Aedes aegypti.
10 October 2008
Improvement of age-grading methodologies
Being able to determine the age of wild-caught mosquitoes is crucial in order to assess the efficacy of our life-shortening approach and the success of mosquito control strategies. In follow-up work from our recent studies (Cook et al.2006 PNAS) we have used microarray analysis to identify additional novel gene candidates that show a strong transcriptional relationship with age. This work represents an improvement to the age-grading model developed previously in the lab and will soon be evaluated in the field.
16 November 2006
Development of new mosquito age-grading technique
A new method for age-grading mosquitoes using transcriptional profiles was published this month in the Proceedings of the National Academy of Science. This work was the result of collaboration between research groups at The University of Queensland, Queensland Institute of Medical Research and James Cook University. The development and evaluation of this method was an early milestone for this project and a valuable technique for the broader mosquito research community.