Bite-sized information about dengue in Singapore
Ans: The Aedes mosquito is generally day-biting and most active during daylight hours with peak biting soon after sunrise and just before sunset.
However, in Singapore’s highly urbanised environment, the Aedes mosquito has been observed to have adapted to artificial lighting and can bite at night as well.
Ans: What you see are Gravitraps, that help monitor the Aedes mosquito population in the vicinity, and helps NEA prioritise resources by directing officers to search and destroy breeding habitats at locations with higher Aedes mosquito populations.
Gravitraps are designed to attract and trap female Aedes mosquitoes looking for sites to lay their eggs. These mosquitoes are not seeking a blood meal and will not bite. These mosquitoes will be captured and thus prevented from subsequently biting others. The Gravitrap also traps and prevents the emergence of mosquitoes from eggs laid in that trap. This way, it helps to reduce the number of mosquitoes emerging from other sites.
Ans: Only 2 species of mosquitos – the Aedes aegypti and the Aedes albopictus – are able to transmit dengue in Singapore.
The Aedes aegypti is the most efficient vector of dengue. It has adapted to living in close proximity to humans, thriving in urban areas, with a preference for biting humans. It typically breeds in artificial or natural water containers and bodies, like flower pot plates and trays. The risk of getting dengue is thus higher in areas with high human congregation, like urban residential areas, including parks and playgrounds.
The Aedes albopictus is commonly found in forests, and other areas with much greenery. It’s not as efficient in transmitting dengue, but has been responsible for outbreaks overseas when present in large numbers in densely populated areas. There is therefore some risk of getting dengue in our green spaces, but the risk is comparatively lower than in residential areas.
When visiting parks and other nature areas, protect yourself from mosquito bites by applying insect repellent and wearing long-sleeved, loose fitting and light-coloured clothing.
Ans: Repellents containing DEET (N,N-diethyl-m-toluamide) picaridin or IR3535 as the active ingredient are the most effective in repelling mosquitoes. These products are safe, even for pregnant women and nursing mothers. Products with less than 10% DEET are safe for young children and infants from 2 months of age.
The effectiveness of repellents based on plant-based extracts like citronella, eucalyptus and other essential oils varies from person to person and usually require more frequent application. They can generally provide some protection, but are less effective.