Anti-mozzie efforts and Zika scare rein in dengue

Singapore had been bracing itself for an all-time high when weekly infections of dengue topped 600 in January, in what was traditionally a low period for this mosquito-borne infectious disease. But steps to battle Zika have helped prevent dengue infe
Singapore had been bracing itself for an all-time high when weekly infections of dengue topped 600 in January, in what was traditionally a low period for this mosquito-borne infectious disease. But steps to battle Zika have helped prevent dengue infections.ST PHOTO: LIM YAOHUI

Total number of cases this year may be around 13,000, much lower than the feared 30,000

As the year draws to a close, the total number of dengue infections in 2016 is likely to be less than half of what experts were predicting just some months back. The scare caused by Zika, another mosquito- borne disease, could have contributed to reining in dengue.

The total number of infections so far this year is 12,864, which suggests that Singapore should end 2016 with around 13,000 dengue cases. This is a far cry from the 30,000 cases that experts had warned of in the early part of the year, when Singapore experienced an unusually sharp unseasonal surge in dengue infections.

The country had been bracing itself for an all-time high when weekly infections topped 600 in January in what was traditionally a low period for this mosquito-borne infectious disease.

The jump was caused by a switch in the dominant dengue serotype, which usually spells a spike in cases as the immunity in the community would be low.

This raised fears that infections could soar when the mid-year peak season came around, and that numbers would exceed the high of more than 22,000 infections in 2013, which killed eight people.

Generally, about 20 per cent of people diagnosed with dengue end up needing hospital care. This would have put a strain on public hospitals.

By April, the numbers had fallen to under 300 infections a week. But in August, they trended up again, only to fall sharply when the country went into overdrive to fight the outbreak of Zika.

The sustained campaign against mosquitoes sparked by Zika reined in dengue infections, too. There have been fewer than 100 new cases a week since the end of October, though the number has crept up slightly over the past three weeks.

A National Environment Agency spokesman said the surge in cases caused it to launch its Do The Mozzie Wipeout campaign earlier than usual, on Feb 28, to clear out mosquito breeding.

It found and destroyed 13,000 breeding spots, half of which were in homes, mainly in containers and flower pot trays, between January and December. Construction sites accounted for 5 per cent of breeding sites found.

She said: "Since then, we have observed a decline in the case numbers, and these have been fluctuating at less than 100 cases per week for the past few weeks."

This is less than half the numbers seen at this time last year. Nevertheless, total infections this year are about 2,000 more than last year.

There have also been nine deaths, including that of a young boy, compared to four last year.

A Ministry of Health spokesman said: "Deaths due to dengue are a result of individual patient factors, such as age, co-morbidity and history of previous infection. The risk of death due to dengue is highest among vulnerable individuals such as those who are elderly or have pre-existing medical conditions."

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A version of this article appeared in the print edition of The Straits Times on December 08, 2016, with the headline 'Anti-mozzie efforts and Zika scare rein in dengue'. Print Edition | Subscribe