13 dengue deaths in first half of 2024, more than double last year's total
As of Jul 22, the total number of reported dengue cases stood at 10,141 for 2024
A total of 13 people died from dengue in the first half of 2024, more than double the total for last year. Figures from the National Environment Agency's (NEA) latest dengue surveillance data, published on Wednesday (Jul 24), showed that six people died from April to June. Seven deaths were reported in the first quarter of this year.
Singapore recorded six dengue deaths last year and 19 in 2022, when there was a dengue outbreak. More than 10,100 cases have been reported so far this year, exceeding the total number recorded for the whole of 2023. The threshold was crossed in the week of Jul 14 to Jul 20, when 236 cases were reported. Dengue cases tend to peak from May to October. According to NEA's report, there were 4,090 dengue cases in the second quarter of this year, a 20.8 per cent decrease from the preceding three months.
Results of positive dengue samples tested between April and June showed that dengue virus serotype 2 (DENV-2) accounted for 52.2 per cent of the infections. It is followed by DENV-3, at 33.2 per cent. In the last quarter, NEA identified 432 clusters, down 16 per cent from the first three months of this year. Of the 432 clusters, 360 were closed in the same period. NEA also detected about 4,800 mosquito breeding habitats in the second quarter, a 5 per cent decrease from the preceding three months.
related:
Over 10,000 dengue cases so far in 2024, exceeding total number of infections in 2023
Singapore’s dengue case tally in 2023 stood at 9,949, which was far lower than the 32,173 cases recorded in 2022
Dengue case numbers in 2024 have crossed the 10,000 mark, surpassing the number of cases logged for the whole of 2023. According to latest figures by the National Environment Agency (NEA), there were 267 dengue cases between July 14 and July 22, and that took the total number of local infections this year to 10,141.
The dengue case tally in 2023 stood at 9,949, which was far lower than the 32,173 cases recorded in 2022. In March, NEA warned of a surge in dengue infections after numbers shot up ahead of the traditional peak dengue season from May to October. NEA at the time said the number could go up in the coming months, given the high Aedes aegypti mosquito population here and the low population immunity to dengue.
As at July 22, Singapore has recorded 70 active dengue clusters. They include 10 red-alert clusters, which are high-risk areas with 10 or more cases. The largest active cluster stands at 410 cases in a housing estate in Bukit Panjang, off Cashew Road. It is followed by a cluster in Jurong West with 103 cases and another cluster in the Pioneer area, near Benoi Road, with 47 cases.
Dengue Cases
237 dengue cases were reported in the week ending 20 July 2024, 54 cases fewer than in the previous week. The weekly number of reported dengue cases remains consistently high. It is important to note that the day-to-day numbers fluctuate, as they depend on the number of cases notified each day. Therefore, weekly numbers are a better reflection of actual trends.
70 active dengue clusters, of which 10 were with red colour alert (i.e. cluster with 10 or more cases), were reported as of 22 July 2024. Fast rate of dengue transmission has been observed at the 103-case cluster at Jurong West Avenue 1/Street 42. Persistent dengue transmission is noted at the 410-case Gangsa Road cluster and 47-case Benoi Road cluster. The 52-case Hindhede Walk cluster has closed on 19 July 2024, while the 103-case Jurong Lake Link/Jurong West Street 41 cluster and 66-case Jurong East Avenue 1/Street 31 cluster have closed on 22 July 2024.
There are four Dengue virus serotypes circulating in Singapore. Dengue virus serotype 2 (DENV-2) has been predominant since September 2023, with prior periodic dominance of DENV-1 and DENV-3 in 2023. Our population’s immunity to all four Dengue virus serotypes remains low. The continued presence of all these dengue risk factors may lead to a surge in dengue cases in the coming months, if insufficient action is taken. There are currently no Zika clusters. Nine isolated Zika cases have been reported in 2024 to date.
How Mosquitoes Work
Mosquitoes have been around for over 30 million years
In this article, we'll take a close-up look at mosquitoes -- how they breed, how they bite, what diseases they carry and what you can do to control them. Up close, mosquitoes are insects that have been around for more than 30 million years. And it seems that, during those millions of years, mosquitoes have been honing their skills so that they are now experts at finding people to bite. Mosquitoes have a battery of sensors designed to track their prey, including:
- Chemical sensors - mosquitoes can sense carbon dioxide and lactic acid up to 100 feet (36 meters) away. Mammals and birds gives off these gases as part of their normal breathing. Certain chemicals in sweat also seem to attract mosquitoes (people who don't sweat much don't get nearly as many mosquito bites).
- Visual sensors - if you are wearing clothing that contrasts with the background, and especially if you move while wearing that clothing, mosquitoes can see you and zero in on you. It's a good bet that anything moving is "alive", and therefore full of blood, so this is a good strategy.
- Heat sensors - Mosquitoes can detect heat, so they can find warm-blooded mammals and birds very easily once they get close enough.
Something with this many sensors sounds more like a military aircraft than an insect. That's why mosquitoes are so good at finding and biting you. As we'll see later, one of the only ways to stop mosquitoes from finding you is to confuse their chemical receptors with something like DEET. Like all insects, adult mosquitoes have three basic body parts:
- Head - This is where all the sensors are, along with the biting apparatus. The head has two compound eyes, antennae to sense chemicals and the mouth parts called the palpus and the proboscis (only females have the proboscis, for biting).
- Thorax - This segment is where the two wings and six legs attach. It contains the flight muscles, compound heart, some nerve cell ganglia and trachioles.
- Abdomen - This segment contains the digestive and excretory organs.
- So you have a sensor package, a motor package and a fuel processing package -- a perfect design!
Mosquito
Mosquitoes, the Culicidae, are a family of small flies consisting of 3,600 species. The word mosquito (formed by mosca and diminutive -ito) is Spanish and Portuguese for little fly. Mosquitoes have a slender segmented body, one pair of wings, three pairs of long hair-like legs, and specialized, highly elongated, piercing-sucking mouthparts. All mosquitoes drink nectar from flowers; females of some species have in addition adapted to drink blood. Evolutionary biologists view mosquitoes as micropredators, small animals that parasitise larger ones by drinking their blood without immediately killing them. Medical parasitologists view mosquitoes instead as vectors of disease, carrying protozoan parasites or bacterial or viral pathogens from one host to another.
The mosquito life cycle consists of four stages: egg, larva, pupa, and adult. Eggs are laid on the water surface; they hatch into motile larvae that feed on aquatic algae and organic material. These larvae are important food sources for many freshwater animals, such as dragonfly nymphs, many fish, and some birds. Adult females of many species have mouthparts adapted to pierce the skin of a host and feed on blood of a wide range of vertebrate hosts, and some invertebrates, primarily other arthropods. Some species only produce eggs after a blood meal.
The mosquito's saliva is transferred to the host during the bite and can cause an itchy rash. In addition, blood-feeding species can ingest pathogens while biting, and transmit them to other hosts. Those species include vectors of parasitic diseases such as malaria and filariasis, and arboviral diseases such as yellow fever and dengue fever. By transmitting diseases, mosquitoes cause the deaths of over 725,000 people each year.
related:
