Homes in landed residential estates have higher incidence of Aedes mosquito breeding. Residents face a higher risk of getting dengue and should maintain vigilance in housekeeping, even going beyond the Mozzie Wipeout  

Singapore, 30 October 2020 – As of 29 October 2020, there have been 32,806 reported dengue cases this year, with 565 cases reported last week. While the number of cases is  about five per cent lower than the week before, the rate of decline has slowed down and the number of weekly dengue cases still remains high. The adult Aedes aegypti mosquito population has increased over seven consecutive weeks, with the National Environment Agency (NEA)’s Gravitrap surveillance system detecting a 26 per cent increase in the mosquito population since the beginning of September. NEA has also found a higher incidence of Aedes mosquito breeding and dengue cases in homes in landed residential estates, compared to homes in private high-rise apartments and HDB flats. In August and September, the dengue incidence rate [1] (the number of dengue cases per 100,000 population) is estimated to be about 820 per 100,000 residents living in landed residential homes, or about three to six times higher than for residents living in private apartments and HDB flats. From January to September 2020, the number of dengue cases in landed residential homes also accounted for about 25 per cent of the total number of dengue cases in Singapore. This is proportionally higher than the percentage of landed residential homes in Singapore.

Dengue prevention measures at landed residential estates  

2          The topography of landed residential homes is more favourable for mosquito breeding than private apartments and HDB flats. This is due to the larger surface areas, and greater variety of structures and receptacle types, within landed residential homes and their compounds, which are conducive for harbouring mosquito breeding habitats. In addition to the usual domestic and ornamental containers, and plant and flower pot plates/ trays found in most residential homes, mosquito breeding are also found in water fountains, roof gutters and drains within the compounds of landed estates. A recent poll conducted in August by REACH, on the sentiments of Singaporeans towards the ongoing dengue situation, revealed that residents in landed residential homes were the most concerned about the dengue situation. Yet less than half of the residents polled in landed residential homes said that they had cleared blockages in their roof gutters and drains, and/or had put Bti (Bacillus thuringiensis israelensis) larvicide in them, in the past week.

3          During inspections in landed residential homes, NEA continues to detect a high incidence of Aedes mosquito breeding. Residents are urged to take measures to prevent mosquito breeding within their homes and compounds, and even go beyond the Mozzie Wipeout. Some additional measures include: turning over containers and storing them under shelter when not in use; covering any water storage containers and using the water in such containers promptly; maintaining water fountains regularly and scrubbing the interior surfaces of fountains to remove mosquito eggs that can attach to such surfaces; as well as clearing roof gutters and drains within the compounds, to prevent chokes and accumulation of stagnant water. Bti larvicide should also be added to stagnant water bodies that cannot be removed. Diligently carrying out all the above actions will lower the risk of being infected with dengue, and thus protect residents and their families.

Dengue cluster situation update

4          162 dengue clusters have been reported as of 29 October 2020, a decrease of fifteen clusters from the previous week. With the concerted efforts of NEA and the community and stakeholders, the following dengue clusters were closed last week:  

• 193-case cluster at Changi Road / Chiku Road
• 112-case cluster at Bishan Street 11
• 106-case cluster at Carpmael Road / Ceylon Lane
• 57-case cluster at May Road / McNair Road

5          Overall, we have closed about 94 per cent, or 2,657 of 2,819, of the dengue clusters notified since the beginning of this year. We have also observed a slower rate of disease transmission at some of the larger dengue clusters, such as the 91-case cluster at Fernvale Road, with an average of less than one case reported per day in the past two weeks.

6          However, the total number of dengue clusters reported islandwide remains high. There are still large dengue clusters at Lorong 1 Toa Payoh, Pasir Ris Drive 10, Carman Street / Elite Park Avenue, Cambridge Road and Cheng Soon Garden, where intensive vector control operations are ongoing. To combat these large dengue clusters, NEA has been working intensively with key stakeholders from various Government agencies in the Inter-Agency Dengue Task Force (IADTF), including Town Councils, on sustained environmental management efforts.

Community must work together to prevent a second dengue surge this year  

7          Even though we are moving beyond the traditional dengue peak season of May to October, the number of dengue cases is still high, hovering at around 500 to 600 cases per week for the past five weeks. Together with the increasing Aedes aegypti mosquito population, this may lead to another surge in dengue cases in the coming months. NEA and our partners in the IADTF have thus kept up inspections at dengue cluster areas, and maintained a high tempo of preventive inspections for mosquito breeding and dengue cluster operations, in order to further slow down dengue transmission. NEA also continues to work closely with Grassroots Advisers and community volunteers, to reach out to and advise residents on dengue prevention efforts.

8          It is critical that stakeholders and the public continue to work together with NEA, to arrest the rise in the Aedes aegypti mosquito population in the community and break disease transmission. Residents, especially those residing in dengue cluster areas, should do their part and carry out the three protective actions against dengue – spray insecticide in dark corners around the house, apply insect repellent regularly, and wear long-sleeve tops and long pants. All stakeholders should also continue to do the Mozzie Wipeout at least once a week, and ensure that their homes, premises and immediate surroundings are free from stagnant water.

[1] The dengue incidence rate is estimated from population data on Singstat’s webpage.

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