As 2016 draws to a close, the year’s total number of dengue infections is likely to be less than half of what experts were predicting just months ago.

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 early this 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 viral 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 fell to under 300 infections a week.

But in August, it 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.

The spokesman 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 been nine deaths, compared with 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.”

salma@sph.com.sg

This article was first published on Dec 8, 2016.
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