Increase in dengue cases due to warmer year-end weather: Expert

An expert says the dengue virus follows the mosquitoes' breeding cycles, which have shortened. As a result, more people are infected.
Liyana Othman Channel NewsAsia 12 Dec 15;

SINGAPORE: October is when the traditional dengue peak period ends. Yet, the number of cases recorded this October and November were higher than those in the same months last year.

Figures from the National Environment Agency (NEA) show 274 cases of dengue reported so far this week, even before the week ends on Sunday. This is 13 cases more than the previous week. Similarly, statistics on the Health Ministry website show an up trend in the number of dengue cases from October onwards, compared to the same period last year.

This has been attributed to slightly warmer than usual year-end weather, due to the El Nino phenomenon.

Said Dr Leong Hoe Nam, Infectious Diseases Specialist, Mount Elizabeth Noeva Hospital: "The weather is getting warmer. The virus follows the mosquitoes' breeding cycles, which have shortened, and because of that, it infects more people. What we're more worried about is that we're going into 2016, and the mosquito transmission rate is so high. So come next year, the number of dengue cases might even be higher."

Earlier this week, a 59-year-old Singaporean woman died from the virus. She lived at Jalan Minggu, which is part of a cluster identified by NEA as a high-risk area. The cluster includes Jalan Chegar, Jalan Isnin, Jalan Khamis, Jalan Rabu, and Block 23 Sin Ming Road.

Residents Channel NewsAsia spoke to expressed their concerns and shared measures to deter the Aedes mosquitos from breeding in their homes.

"We make sure that the water is cleared, especially the potted plants," said one resident, while another said they keep their containers covered before going away on holiday.

"Make sure there's no stagnant water around. I myself have gotten dengue three times in my life, so I'm quite cautious," said a third resident.

Currently, the top hot spot is a cluster spanning Tampines Ave 3, Ave 4, Street 81 and Street 91, with 109 cases since the start of the cluster.

Authorities also urge the public to check their surroundings regularly and take measures to eradicate any mosquito breeding habitats.

- CNA/dl

Dengue cases hit unusual year-end high
Yuen Sin, Straits Times AsiaOne 16 Dec 15;

A total of 361 dengue cases were reported last week, the highest weekly number recorded so far this year, the National Environment Agency (NEA) said yesterday.

While higher weekly numbers have been recorded in the past two years, with a weekly high of 891 cases last year and 842 in 2013, these were recorded around June and July - not towards the end of the year.

Four people have died of dengue fever this year, three in recent months.

Last Wednesday, a 59- year-old woman died at Khoo Teck Puat Hospital. She lived in Jalan Minggu, in Upper Thomson, an active dengue cluster.

On Nov 28, a 79-year-old man died a few days after being admitted to Tan Tock Seng Hospital.

The other victims were a 60-year-old from India who was visiting her son here in September, and a 53- year-old woman from China who died in February.

Dengue outbreaks are usually triggered by the interplay of weather conditions and a change in the dengue strain, according to Professor Annelies Wilder-Smith, who studies infectious diseases at the Lee Kong Chian School of Medicine.

While the number of dengue cases in the first 10 months of this year fell by about half compared with the same period last year, the Aedes mosquito population has doubled.

The NEA said warmer than usual year-end weather caused by the El Nino phenomenon could result in shorter mosquito breeding periods and shorter incubation times for the dengue virus.

The DENV-2 serotype, which had been the dominant strain before 2013 until it was replaced by DENV-1, has now returned.

Dengue cases due to the DENV-2 serotype have increased, accounting for half of all cases here.

A switch in the dominant strain usually signals a higher number of infections as fewer people would have immunity.

A total of 10,142 dengue cases were reported as of Dec 12. In the whole of last year, there were 18,335 cases with five local deaths.

There were 60 active dengue clusters as of Monday, with 114 cases recorded in the largest cluster of Tampines Avenue 3 and Avenue 4, and Tampines Street 81 and Street 91.

Twenty-three of the cases were identified with the DENV-2 strain.

The longest-existing cluster, which has been around since Oct 13, is at Eastwood estate in Bedok.

IT surveillance consultant Eric Lee, 47, was hospitalised for five days after contracting dengue early last month.

The Eastwood Way resident suspects that he contracted the disease within his housing estate.

"Mosquito breeding in this estate is still prevalent," he said.

The NEA said anyone infected with dengue should apply mosquito repellent to prevent mosquitoes from biting them and infecting others, and that those with symptoms should consult a doctor.

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