Dengue is transmitted from an infected human to a susceptible human through a mosquito bite. Hence, the risk of dengue is highest in places where there is an infected human and an efficient mosquito vector.
Over 170 species of mosquitoes have been identified in Singapore by NEA’s Environmental Health Institute (EHI) to-date, with most species found in rural forested areas. Only two species – Aedes aegypti and Aedes albopictus – are able to transmit dengue in Singapore.
Aedes aegypti is the most efficient vector of dengue and it has adapted to living in close proximity to humans, thriving in urban areas and with a preference for biting humans. It typically breeds in artificial or natural water containers/bodies, such as household water storage containers and flower pot plates/trays. The risk of dengue is thus higher in areas with high human congregation such as urban residential areas, including parks and playgrounds located therein, where there is higher likelihood of finding Aedes aegypti and infected humans, compared to forested areas where Aedes aegypti and infected humans are less likely to be present. This is in agreement with surveillance results from EHI. Whilst it is common to detect dengue virus in mosquitoes from residential areas, no dengue virus has been detected in the tens of thousands of mosquitoes collected from forested areas.
Aedes albopictus, commonly found in forests and also in parks and areas with much greenery, is a secondary vector. Though not as efficient in transmitting dengue as Aedes aegypti, it has been responsible for outbreaks overseas when present in large numbers in densely populated areas. There is therefore some risk of acquiring dengue through this mosquito in our green spaces, particularly those with higher human traffic. However, the risk is comparatively lower than that in residential areas.
When visiting parks and other nature areas, members of the public can protect themselves from mosquito bites, by applying insect repellent and wearing long-sleeved, loose fitting and light coloured clothing.
Posted on 24 May 2016 05:44 AM