Aedes aegypti or yellow fever mosquito. Close up a Mosquito sucking human blood,Vector borne diseases, Chikungunya, Dengue fever Rift Valley fever, Yellow fever, Zika, from Shutterstock.com

NEA does not really answer why the sudden spike of dengue cases by attributing to increase of mosquito numbers

The National Environment Agency (NEA) revealed on Friday (19 July) that the increase in population of Aedes aegypti mosquito, warmer weather and a low herd immunity are the reasons that led to high number of dengue cases recorded in the country this year.

For those who are unaware of the current situation in Singapore, on Monday (15 July), NEA stated that the figure for dengue cases in a week has hit a new 5-year high, with 665 cases recorded from 7 to 13 July.

If that is not all, the figure also surpassed the previous weekly peak of 637 cases recorded in January 2016. The highest weekly number of cases in recent years was 891 cases in July 2014.

“A total of 7,373 dengue cases have been reported this year (as of 13 July 2019), about five times more than 1,481 dengue cases we saw in the same period last year,” said the Agency.

To highlight the seriousness of this problem, 44 individuals have had the more severe dengue haemorrhagic fever, and five people have lost their lives so far – equal to the total death count in 2018 alone.

Key reasons for high dengue cases

To address this issue, NEA explained in its media advisory that based on its surveillance, it found that the number of Aedes aegypti mosquito has increased by almost three times since the last outbreak in 2013, adding that the mosquito population has been “persistently high”.

On top of that, the Agency also noted that the mean temperature for the first half of 2019 was 0.7 degrees higher than that during the same period last year.

“Warmer temperatures result in higher transmission of dengue due to the accelerated development of the Aedes mosquito and shorter incubation period of the dengue virus,” explained the Agency.

It added, “At the same time, a large proportion of our population continues to be susceptible to dengue, given our population’s low herd immunity.”

The proportion of adults who have had dengue before has reduced from 59% in 2004 to 41% in 2017.

However, based on TOC’s previous article, we have mentioned that NEA’s chart showed that the number of dengue cases were on an upward trend since March and not a sudden spike in June.

According to our sources, the Agency is also uncertain as to what caused the spike in dengue cases and is trying to figure it out.

But based on their latest explanation, it looked like they only provided reasons to justify the high number of cases recorded, but not why is there a sudden spike last month.

Although an increase of Aedes mosquitoes is a cause, it does not account for the sudden hike.

Apart from that, the temperature also did not fluctuate dramatically this year compared to last year. As such, we can’t help but wonder why the number of dengue cases shoot up so much in June.

Channel News Asia (CNA) also reported on NEA’s latest development where it included a graph of dengue cases recorded only from 2013 to 2018.

This shows the poor reporting done by the news site because if it had used the trend shown for 2019, then readers would have grasp the horror of the sudden spike in June this year which NEA has yet to account for.