Singapore set to avert record number of dengue cases

TAN WEIZHEN Today Online 23 Nov 16;

SINGAPORE — With the number of dengue cases steadily declining, Singapore looks set to avoid the worst-case scenario of a record 30,000 cases predicted by the authorities at the start of the year, when cases spiked alarmingly.

The number of cases this year is at 12,708 as of Wednesday (Nov 23) — worse than the 11,200 of last year, but nowhere near the levels in 2013 when the number of cases reached a record 22,170.

The latest weekly figures for reported cases, provided by the National Environment Agency (NEA), showed that there were 72 cases for the week ending Nov 19. The numbers have been falling progressively, from 107 cases for the week ending Oct 22.

Although this period is traditionally the low season for mosquitoes, the latest numbers are still lower when compared with the same period in previous years.

Earlier this year, there was an alert from NEA that the number of dengue cases in 2016 may exceed 30,000 “unless immediate action is taken”. Its spokesman said that the Do the Mozzie Wipeout campaign against mosquito-breeding was launched and an inter-agency dengue taskforce was activated to get more public agencies to help monitor breeding sites.

“Since then, we have observed a decline in the case numbers, and these have been fluctuating at fewer than 100 cases per week for the past few weeks,” the spokesperson added. The authorities also roped in a large number of volunteers to lead the fight on the ground.

In February, the People’s Association said that it had gathered more than 5,000 grassroots leaders and volunteers for house visits, targeting areas with a high number of dengue cases.

In April, the NEA said that it would train 5,000 more dengue-prevention volunteers this year, to nearly double the pool of 5,800 such volunteers who educate the public on getting rid of breeding sites.

There was a S$200 fine implemented earlier this year for owners of homes found to have breeding spots, regardless of whether they are situated in a dengue cluster. Member of Parliament Louis Ng (Nee Soon GRC) said: “I think the fine made people realise that the crackdown on dengue was getting serious. So, together with the campaigns, more started to take responsibility (to keep) their homes free of breeding grounds.”

Incidentally, the Zika scare and the subsequent control measures also played a part in the fight against dengue. In August, Singapore had its first locally transmitted case of the mosquito-borne Zika virus, and MPs and infectious diseases experts observed that people had become more vigilant about clearing potential breeding places in their homes because of this.

Professor Tikki Pang, adviser of Asian Dengue Vaccination Advocacy group, said that the intensified vector control by the authorities would have had an impact on controlling dengue as well. The MPs and experts said that it is now possible for the low number of cases to be sustained, but this hinges on people continuing to do their part to prevent mosquito-breeding.

“It is about whether the public can be on high alert continuously, especially now that the Zika scare has worn off,” Prof Pang said.

The visiting professor at the Lee Kuan Yew School of Public Policy said it is also possible that the dengue type could change next year. “If it changes to dengue type 3, then we might have an increase in the number of cases.”

In the week ending Nov 19, the number of reported Zika cases had tapered off to just three. As of yesterday, three clusters remain — two of which have no new cases reported in the past two weeks.
Dr Chia Shi-Lu, MP for Tanjong Pagar GRC, said: “I do feel optimistic. The results have shown that if everyone plays their part, it does make a significant impact. Then, if we have other measures like Wolbachia and dengue vaccines, it could curb the spread. All these measures will have additional impact.”

Last month, Singapore started a Wolbachia trial, where male Aedes aegypti mosquitoes carrying the naturally occurring Wolbachia bacteria were released in Braddell Heights housing estate (followed by Tampines West and Nee Soon East) as part of a field study to control the mosquito population and the spread of diseases such as dengue.

When female Aedes aegypti mosquitoes mate with the Wolbachia-carrying males, their eggs will not hatch because they are biologically incompatible.