DENGUE cases here are expected to increase, as the population of the Aedes aegypti mosquito – which transmits dengue and other viruses – has grown by about 30% in April, compared with January, said the National Environment Agency (NEA).
The mosquito population has remained high in some residential areas across the island.
Over 2,700 dengue cases have been reported since the start of this year and there are currently 22 active dengue clusters.
Although there have been fewer dengue cases in recent weeks than in the same period last year – when a historic outbreak of dengue occurred in Singapore – the figures remain higher than those of 2017 and 2018, years that saw 2,772 and 3,285 cases respectively.
There were 35,315 reported dengue cases last year, with 28 deaths.
“As we have now entered the warmer months of the year from June to October, the increased risk of higher dengue transmission is a concern, ” the agency said yesterday.The NEA expects more dengue cases due to the accelerated breeding cycle and maturation of the Aedes aegypti mosquito vectors – meaning it takes less time for the mosquito to become a biting adult in warmer months – as well as the shorter incubation period of the dengue virus.
This refers to the time needed for the mosquito to pick up the disease and pass it on.
According to the World Health Organisation, this period is around eight to 12 days when the temperature is 25 to 28 deg C.
Since the Covid-19 phase two (heightened alert) measures began on May 16, the NEA said more people staying in and working from home could mean more “biting opportunities” for the day-biting Aedes aegypti, and potentially higher risk of dengue transmission.
Last August, a study examining the impact of the circuit breaker on the number of dengue infections found there were 50% more cases than usual.
The study, which was conducted in collaboration with the National University of Singapore’s Saw Swee Hock School of Public Health, also found that adults aged 20 to 64 made up the majority of infections since that part of the population would have normally been in the workplace during the day.
In addition, more than half of the positive dengue samples since February were due to the less common dengue serotypes 3 (DENV-3) and 4 (DENV-4).
Serotypes are distinct variations within a particular virus. There are four dengue serotypes: DENV-1,2, 3 and 4. The predominant dengue virus serotype in Singapore has been DENV-2 since 2016.
The NEA said that since DENV-3 has not been dominant for about the last three decades and the incidence rate of DENV-4 has also been consistently low, the population immunity for both serotypes is low, making people more likely to get infected. — The Straits Times/ANN