More mosquitoes, warmer weather call for vigilance against dengue: NEA

The National Environment Agency says it has observed an increase in the Aedes mosquite population, and warmer year-end weather due to the El Nino phenomenon.
Channel NewsAsia 2 Dec 15;

SINGAPORE: The National Environment Agency (NEA) is urging members of the public and stakeholders to stay vigilant and continue to work as a community to prevent dengue cases from rising.

In a media release issued on Wednesday (Dec 2), NEA said it is observing an increase in the Aedes mosquito population and slightly warmer weather than is usually expected during the year-end period due to the El Nino phenomenon.

"The warmer conditions support faster breeding and maturation cycles of the Aedes mosquitoes, and shorten incubation periods for the dengue virus," the agency said.

It added that the proportion of dengue cases due to the DENV-2 serotype has increased and now accounts for half of all dengue cases in Singapore. Since March 2013, it had been the DENV-1 serotype that had accounted for most of the dengue cases.

"This change in the main circulating dengue virus may be an early indicator of a future dengue outbreak unless measures are taken to suppress the Aedes mosquito population," said NEA.

The agency said that as of Oct 31, 8,520 dengue cases have been reported, which is about 48.6 per cent lower than last year's figure of 16,569 for the same period. However, the current Aedes mosquito population is double that seen during the same period in 2014.

NEA added: "As a large proportion of our population is still susceptible to dengue infection due to the lack of immunity, an increase in the Aedes mosquito population and slightly warmer-than-usual weather could lead to a surge in dengue cases unless measures are taken to suppress the Aedes mosquito population.

"All stakeholders need to ensure that their premises are free of stagnant water which could lead to mosquitoes breeding and step up efforts to stem dengue transmission."

NEA said it will continue to closely monitor areas with active transmission of dengue and the transmission patterns, and work with the Inter-Agency Dengue Task Force, as well as Town Councils, to rid public areas and housing estates of potential mosquito breeding habitats.

It also advised the public and stakeholders to take appropriate precautions to prevent mosquito breeding by practising the five-step "Do the Mozzie Wipeout" and regular use of repellents.

- CNA/hs


More dengue-carrying mosquitoes than usual in October
Today Online 2 Dec 15;

SINGAPORE — While the end of the year typically signals a relief from the Aedes mosquitoes that carry dengue, the authorities have cautioned that the Aedes mosquito population in October was double what was seen in the same month last year.

“We are seeing an increase in the Aedes mosquito population, and are also experiencing a slightly warmer-than-usual year-end weather due to the El Nino phenomenon,” the National Environment Agency (NEA) said in a statement today (Dec 2).

Warmer weather supports faster breeding and maturation cycles of the Aedes mosquitoes and shortens the incubation period of the dengue virus. The agency urged the public to stay vigilant to prevent dengue cases from rising.

While the weekly number of dengue cases was on a downward trend this time last year, there were 284 cases last week, up from 254 the previous week and the second consecutive increase.

The NEA also noted there has been a 48.6 per cent dip in dengue cases reported in the first ten months of this year from the same period last year — 8,520 cases this year compared with 16,569 last year. However, the proportion of dengue cases caused by the DENV-2 serotype has increased.

The DENV-2 serotype now accounts for half of all dengue cases in Singapore. “As a large proportion of our population is still susceptible to dengue infection due to the lack of immunity, an increase in the Aedes mosquito population and slightly warmer-than-usual weather could lead to a surge in dengue cases unless measures are taken to suppress the Aedes mosquito population,” the NEA said.


More Aedes mosquitoes because of warm weather
Samantha Boh, The Straits Times AsiaOne 4 Dec 15;

The Aedes mosquito population has grown, coinciding with the warmer-than-usual year-end wea-ther, said the National Environment Agency (NEA) yesterday .

The proportion of dengue cases due to a variant virus - the DENV-2 serotype - has also risen and they now account for half of all cases, an increase from about 44 per cent in mid-May.

This could mark an impending shift from the DENV-1 serotype that had accounted for most of the dengue cases since March 2013.

NEA said the change in the main circulating virus may be an early indicator of a future dengue outbreak. The last serotype switch, from DENV-2 to DENV-1 in March 2013, resulted in a historic high of 22,170 cases that year.

As of Oct 31, 8,520 cases have been reported. This is about 48.6 per cent lower than the 16,569 in the same period last year. However, the Aedes mosquito population in October was double that in October last year.

NEA noted that warmer conditions caused by El Nino could result in shorter breeding periods for Aedes mosquitoes and shorter incubation times for the dengue virus.

"As a large proportion of our population is still susceptible to dengue infection due to the lack of immunity, an increase in the Aedes mosquito population and slightly warmer-than-usual weather could lead to a surge in dengue cases unless measures are taken to suppress the Aedes mosquito population," NEA said. It urged people to take measures to prevent mosquito breeding in and around their homes.

As of Tuesday, there were 48 dengue clusters.There were 284 cases of dengue in the week ended Nov 28, a slight increase from the 254 cases the week before.