Singapore headed for worst dengue year, with 30,000 cases projected

LOUISA TANG Today Online 19 Feb 16;

SINGAPORE — The ongoing El Nino phenomenon, along with a change in the type of dengue virus circulating among Singapore’s population, have led the authorities to forecast a historic high of 30,000 dengue cases this year, nearly a third higher than the previous record of 22,170 cases in 2013.

And with the looming threat of the Zika virus — also spread by the Aedes aegypti mosquito — adding greater urgency to the need to control the mosquito population, the authorities will be taking early action.

In a media briefing by the National Environment Agency (NEA), the Ministry of Health (MOH) and People’s Association (PA) on Thursday (Feb 18), the authorities announced that the annual Mozzie Wipeout Campaign, held usually around April, will be launched on Feb 28.

The PA has roped in more than 5,000 grassroots leaders and volunteers for house visits targeting areas with a high number of dengue cases, adding to the more than 5,800 NEA-trained volunteers who will advise residents on anti-mosquito breeding and dengue prevention tips.

An NEA spokesperson also said the agency would be implementing more stringent enforcement measures, such as increasing the frequency of inspections at major construction sites from quarterly to monthly. In preparation for the surge in cases, the NEA, which provides dengue diagnostic services to primary healthcare clinics and hospitals, has increased the number of laboratory staff and extended operating hours, by mobilising staff from other research groups.

In an article on the dengue outlook for the year in MOH’s epidemiological news bulletin published last month, researchers noted that the effects of El Nino will contribute to a rise in cases in the coming months.

After El Nino peaked in December 1997, there was a spike in dengue cases in January 1998, followed by another in August.

The latest episode of El Nino, which quickens the breeding and maturation cycles of the Aedes mosquito, began last year, which saw over 11,200 reported dengue cases.

There has been a 50 per cent increase in Aedes mosquitoes caught in the NEA’s Gravitraps in January compared to the same period last year. Household inspections also turned up 50 per cent more breeding sites as compared to the same period last January, with top breeding spots being domestic containers and flower pot plates or trays.

In addition, the DENV-2 virus serotype now accounts for two-thirds of all dengue cases, replacing DENV-1 as the predominant strain. Historically, a change in the predominant virus serotype is usually followed by a spike in dengue cases. The last serotype switch — from DENV-2 to DENV-1 — in 2013 was followed by a sharp dengue outbreak that year.

Associate Professor Ooi Eng Eong, deputy director of the Duke-NUS Medical School’s Emerging Infectious Disease Programme, said that while dengue forecasting “is an imperfect science as we don’t fully understand all the determinants”, a high number of cases is to be expected this year based on dengue trends so far.

Infectious diseases professor Annelies Wilder-Smith from Nanyang Technological University’s Lee Kong Chian School of Medicine, concurred that the unusual climate conditions, combined with the virus serotype switch, have set the stage for a high epidemic year.

“Furthermore, Singapore has had further population growth. Population density enhances the biting rates and facilitates transmission of dengue virus. With an increasing population size, the absolute numbers of dengue also increase, even if the incidence remains the same,” she added.

More than 3,600 dengue cases have been reported in Singapore since January, with two deaths so far.

In previous years, the NEA has stepped up inspections when the number of dengue cases spiked. In 2014 — when there were 18,335 reported cases — the NEA deployed 850 dengue inspectors who conducted more than 3.5 million inspections and destroyed over 18,400 mosquito breeding habitats. Last year, In 2015, the NEA conducted more than 1.4 million inspections and uncovered more than 19,000 instances of mosquito breeding.

More mosquito traps, manpower to combat possible dengue epidemic: NEA
Singapore's National Environment Agency puts forth an enhanced dengue outbreak response plan in view of a record-breaking number of dengue cases expected in 2016.
Justin Ong Channel NewsAsia 18 Feb 16;

SINGAPORE: The National Environment Agency (NEA) on Thursday (Feb 18) unveiled a stepped-up, six-pronged dengue outbreak response plan after it was announced there could be a record 30,000 dengue cases in Singapore this year.

Firstly, the number of mosquito traps will be increased from 4,000 to about 30,000 across 5,000 public housing blocks, with another 20,000 traps to be rolled out to the remaining 3,000 blocks by June.

NEA also said that the expected increase in dengue cases will see a corresponding surge in diagnostic requests at primary healthcare clinics and hospitals. To deal with this, there will be an increased number of laboratory staff - mobilised from other research groups - and extended operating hours. NEA will also continue to perform serotyping and sequencing of dengue cases to help detect any emergence of the Zika virus - recently declared an international public health emergency.

Third, since 2015, NEA has increased dengue control efforts against construction sites - which are susceptible to breeding mosquitoes with high density of larvae. These include stepping up the inspection frequency of dedicated construction site teams from quarterly to monthly and publishing online a list of sites issued with stop-work orders. NEA will also request temperature screening regimes for workers, encourage them to apply insect repellent as well as to sleep under bed-nets or in air-conditioned sick bays to ward off mosquitoes.

NEA also revealed it was intensifying its outbreak preparedness by bringing forward its annual mobilisation of Inter-Agency Dengue Task Force members to conduct source reduction and killing of adult mosquitoes.

Fifth, NEA said it has been successfully trialing the use of radio-controlled aerial inspection crafts (RAIC) to survey roof gutters elevated beyond safety limits for its officers. There are plans to expand the trial to include an RAIC that can deposit larvicide to destroy mosquito larvae.

Finally, NEA said it will be engaging additional temporary officers to augment its workforce and better manage a dengue outbreak. These officers will help out with the likes of ground inspection, logistics and trap deployment.


NEA has also released a list of recommended practices for members of the public.

Practice the five-step “Mozzie Wipeout” on alternate days
Apply repellent and wear long-sleeved shirts and pants
Spray insecticide in dark corners of the home such as under the bed and sofa, and behind curtains
Cover up toilet bowls, sinks and gully traps and ensure there is no stagnant water at home before going on vacation
Seek medical treatment early if feeling unwell
Participate in dengue prevention campaigns in the neighbourhood
- CNA/jo

More than 30,000 dengue cases expected in Singapore this year: NEA, MOH
Authorities warn that factors such as warmer temperatures and a growing mosquito population could result in a record-breaking number of dengue cases in 2016.
Justin Ong Channel NewsAsia 18 Feb 16;

SINGAPORE: The number of dengue cases in Singapore this year may exceed 30,000, higher than the record of 22,170 reported in 2013, the National Environment Agency (NEA) and Ministry of Health (MOH) said on Thursday (Feb 18).

This is due to factors such as warmer conditions brought about by the El Nino weather phenomenon, faster breeding and maturation cycles of the Aedes mosquito population and a change in the main circulating dengue virus, said both agencies at a joint media briefing.

Singapore has seen more than 3,400 dengue cases reported since January, with two deaths so far.

NEA said the number of Aedes mosquito breeding found in homes has increased by 50 per cent compared to the same period in January 2015, with majority of breeding found in domestic containers and flower pot plates and trays.

The dominant dengue virus has also switched from DENV-1 to DENV-2. Historically, any change in predominant dengue virus serotype is usually followed by a spike in dengue cases, said NEA.

The environment agency also noted that the Zika virus is transmitted via the Aedes mosquito as well. MOH said its proposed Clinical Advisory Group for the Zika virus has already been set up and held its first meeting on Wednesday. The Group will advise medical practitioners on how to answer questions from concerned pregnant mothers. The Zika virus can spread from an infected mother to a foetus, possibly causing brain damage and microcephaly.


Authorities stated that they will continue with efforts to suppress the increasing Aedes mosquito population by closely monitoring and acting on dengue-active public areas and potential mosquito breeding habitats.

More than 126,000 inspections have been conducted islandwide since Jan 31, uncovering more than 1,900 instances of mosquito breeding.

Authorities also urged members of the public to play their part to keep dengue cases down.

Hence, the annual “Do the Mozzie Wipeout” campaign has been brought forward ahead of the traditional mid-year dengue peak season, announced NEA.

The campaign will be launched island-wide next Sunday (Feb 28), and calls on the community to take appropriate precautions to prevent mosquito breeding over a two-week period to cover two rounds of the mosquito breeding cycle.

More than 5,000 People's Association grassroots leaders and volunteers will conduct house visits in dengue cluster areas to disseminate prevention messages in the months ahead.

NEA said it has trained more than 5,800 Dengue Prevention Volunteers so far to help advise residents on anti-mosquito breeding and dengue prevention tips. More dengue alert banners will also be put up in cluster areas.


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