Lek Wan Zhen Channel NewsAsia 31 Jan 19;
SINGAPORE: More than 140 blocks of Housing Board flats in Nee Soon East and Tampines West will be participating in the next phase of a study by the National Environment Agency (NEA) to reduce the Aedes mosquito population and fight dengue.
Male Wolbachia-Aedes mosquitoes, which have been infected with the Wolbachia bacterium, will be released into the expanded test sites at the two estates in phase three of the Project Wolbachia.
When they mate with female Aedes mosquitoes, the eggs the females lay will not hatch, said NEA.
The expansion in study sites follows the success of phase two of the study, which was conducted between April 2018 and January 2019, at smaller areas in Nee Soon East and Tampines West.
Phase two of the field study was designed to address the challenges posed by Singapore’s densely built-up, high-rise urban landscape, said NEA.
The release of male Wolbachia-Aedes mosquitoes from both high floors and the ground at residential blocks helped ensure a better distribution of the infected mosquitoes.
Nee Soon East had its Aedes mosquito population decrease by 80 per cent, while Tampines West saw a fall of 50 per cent.
Citing a similar study in Guangzhou, Professor Ary Hoffmann, Laureate Professor at the University of Melbourne, said that it is possible for the mosquito population to drastically decrease in the long run.
As such, the third phase of the study aims to determine the ways to continue suppressing the dengue-transmitting Aedes mosquito population in the sites where they were released.
Researchers will study the optimal number of male Wolbachia-Aedes mosquitoes to be released into the area during this period.
The third phase, which begins in February, will involve the largest study site so far, reaching over 52,000 households in Nee Soon East and Tampines West.
Source: CNA/zl(hm)
NEA to ramp up dengue research after success in field tests
Project Wolbachia to be expanded to wider areas in Nee Soon East and Tampines West
Cheryl Teh Straits Times 31 Jan 19;
The population of dengue-carrying mosquitoes in Nee Soon East and Tampines West has been cut by at least half after the release of sterile male mosquitoes, which leads to eggs that cannot hatch. And this success will see the scheme, labelled Project Wolbachia, expanded to wider areas in the two estates.
From April last year to this month, the National Environment Agency (NEA) saw an 80 per cent fall in the Aedes mosquito population in a research area in Nee Soon East. The population was halved in the Tampines West study site, the agency said yesterday.
Still, "it is not a magic bullet" that will solve the mosquito problem, said Associate Professor Ng Lee Ching, director of the NEA's Environmental Health Institute. "It will complement what we are doing: source reduction, mozzie wipeout (campaign), and removing as many mosquitoes as possible from the community."
Dengue continues to be a perennial problem for Singapore. There were 455 cases reported in just the first two weeks of this month - triple the number reported over the same two-week period in January last year.
The Wolbachia-Aedes mosquitoes' job is to control and reduce the Aedes aegypti mosquito population, the primary species responsible for transmitting dengue and Zika. Eggs produced from the union of a male Wolbachia-Aedes mosquito and the female Aedes mosquito will not hatch. This limits the number of mosquito larvae each female Aedes mosquito can produce.
Research on the project started in 2009 and the first phase of the field studies started in 2016.
The first small-scale field studies in Braddell Heights, Nee Soon East and Tampines West examined the behaviour of the Wolbachia-carrying Aedes aegypti in the urban environment, such as how far and high they fly, and how well they could compete with their wild counterparts to mate with females.
When male Wolbachia-carrying Aedes aegypti mosquitoes mate with uninfected females, the resulting eggs will not hatch.
The second phase - from April last year to this month - involved a total of 76 HDB blocks comprising about 7,000 households. The agency also released the Wolbachia mosquitoes at higher floors, as only 6 per cent of the adult male Wolbachia-carrying mosquitoes released at the ground floor were later found on the ninth floor and higher.
The next phase, which will start next month, will see a doubling of the number of HDB blocks where the Wolbachia-Aedes mosquitoes are released.
"The data that has been generated through the different phases of the field study is essential in developing an effective long-term mosquito suppression programme for Singapore," said Professor Ary Hoffmann, Laureate Professor at the University of Melbourne.
He is a member of Singapore's Dengue Expert Advisory Programme, which comprises experts on vector-borne diseases from Singapore, Australia, the United Kingdom and the United States.
Decreasing the population of Aedes mosquitoes drastically might be possible in the long run, said Prof Hoffmann, who cited the example of a study in Guangzhou, where the mosquito population was reduced by 99 per cent.
But Singapore faces different challenges, he said. Compared with the urbanised, high-rise environment here, one-to two-storey buildings are prevalent in Guangzhou, which made it easier to control the population.
In the third phase, researchers will look into how many male Wolbachia-Aedes mosquitoes should be released to maintain a low Aedes mosquito population.
The agency will also adjust the number of mosquitoes to be released along the way - to maintain the current mosquito population, or to suppress higher numbers in the expanded area.
They will also develop the production and release of these mosquitoes on a large scale.
Six of these male Wolbachia-Aedes mosquitoes are currently released weekly, for every person in the study area.
The NEA said yesterday that the improved results from phase two are due to the expanded area of study sites and the Wolbachia mosquitoes being released at higher floors, in addition to ground-floor releases.
In the third phase of the project, mosquitoes will be released weekly at 84 blocks in Nee Soon East, and 60 blocks in Tampines West.
With this expansion, the study will involve the largest number of households since it started - with 7,950 in Nee Soon East, and 5,560 households in Tampines West.
Mosquitoes will continue to be released around the HDB blocks, and along common corridors, but not in homes.
Residents at the field study sites might notice an increase in mosquitoes during the field study, but these male mosquitoes released will not bite or transmit diseases, NEA said.
More Wolbachia mosquitoes to be released in an extended test area: NEA
NEO RONG WEI Today Online 30 Jan 19;
SINGAPORE — Wolbachia-infected mosquitoes will be released around more Housing and Development Board (HDB) flats in Nee Soon East and Tampines West, as the National Environment Agency (NEA) continues its study on a technology that can help the country control the spread of dengue.
The number of HDB blocks involved will be doubled to 144 when Phase Three of its study begins next month, the agency said on Wednesday (Jan 30).
When Wolbachia-infected male mosquitoes mate with female Aedes mosquitoes, they will produce eggs that do not hatch.
Through this, NEA hopes to bring down the population of Aedes mosquitoes to prevent the spread of dengue.
In the second phase of the study, the population of Aedes mosquitoes in Nee Soon East was suppressed by about 80 per cent, NEA said.
The other study site in Tampines West had a less satisfactory result, suppressing the Aedes mosquito population by half.
This could be attributed to the discovery of 10 Aedes mosquito breeding sites in Tampines between September and December last year.
“We’re learning as we are going along. This is all part of our learning curve,” said Laureate Professor Ary Hoffmann, a member of the Dengue Expert Advisory Panel.
“We know if we can get the population down, we can then pull back on the number of mosquitoes we release.”
In the upcoming phase, researchers will explore an optimum ratio of Wolbachia-infected mosquitoes to release, in order to keep the Aedes mosquito population in the area low. They will also vary the number of mosquitoes released at different points of the study site.
Male mosquitoes do not bite, hence the mosquitoes released by NEA will not transmit any diseases or pose any health risks. They live only for up to a week as well.
The mosquitoes will be released around blocks and along common corridors, and not in homes, said NEA.
Outreach activities such as distribution of information booklets or door-to-door engagement will take place after Chinese New Year, ensuring that residents are aware of this project before it commences.
NEA can be contacted at 1800-2255-632 if the public has any enquiries or feedback on this project.
