While the current COVID-19 pandemic continues to capture all our attention, an arguably more deadly disease which has always been endemic in Singapore continues to wreak its havoc. This disease is so insidious that it often hides behind the symptoms of COVID-19. It is dengue.
As old as Singapore
Dengue has been endemic in our shores for as long as our history. As recent as 2019, 15,998 cases of dengue were reported and a total of 20 people died from it. As frightening as these numbers may be, they pale in comparison to the situation developing this year.
We are halfway through the year and already the National Environment Agency has reported a cumulative total of 12,539 cases of dengue and 12 people have succumbed to dengue. 1,375 cases of dengue were reported in the week ending 20th June. That is almost 200 cases of dengue every single day. The highest number of dengue cases ever reported in Singapore was 22,170 cases in 2013 and 2020 may break this unenviable record.
To make matters worse, as we enter the warmer months of the year, the breeding and maturation cycle of the Aedes mosquito accelerates. This means they will reproduce faster resulting in an increase in the number of insect vectors that transmit dengue.
To add fuel to this fire, a higher than usual rainfall and deserted construction yards due to the circuit breaker had resulted in pools of stagnant water that serve as effective breeding grounds for the Aedes mosquito. There is a shift in the strain of dengue this year from the usual strain 2 to the strain 3.
The population is more susceptible to the strain 3 dengue as they have not been exposed to it. In addition, due to the shift in the strain the risk of dengue haemorrhagic fever – the deadly form of dengue, is higher as cross-immunity to different strains are only partial.
How to prevent dengue: it starts with the individual efforts of each household. | Photo: iStock
Dengue the Insidious
To make matters even worse, it is difficult for doctors to differentiate between dengue and COVID-19.
Dengue and COVID-19 share many similar symptoms, such as fever, muscle aches, cough, sore throat, and running nose. Given the attention currently heaped on COVID-19, both the patient as well as the physician have to consciously maintain a high level of suspicion for dengue and not be prejudiced by confirmation bias. “As long as it is not COVID” – is not OK.
Furthermore, it is absolutely possible that a patient is suffering from both dengue and COVID-19 simultaneously making it even more challenging for a doctor to diagnose. As if all these were not bad enough, a final complication exists which is the blood tests for dengue are not always accurate. This was very well illustrated by a local case report of a patient who presented to his doctor with fever and muscle aches and subsequently tested positive on a dengue test.
On further testing, the patient was eventually diagnosed with COVID-19 and it was discovered his initial dengue test was falsely positive. Other supporting blood tests like platelet counts and liver function tests can also show the same abnormalities in both patients who suffer from dengue and patients who suffer from COVID-19, so are also rather unhelpful.
How Dengue Spreads
Dengue is not spread from person to person like COVID-19. A mosquito stings a dengue patient and sucks the dengue parasite along with the blood from its victim into itself. Mosquitos do not fall sick from dengue. They fly to another person and while stinging them, transmits the dengue virus. This means that while social distancing can protect us from COVID-19, it does nothing to protect us from dengue. Dengue can be spread as far as the mosquito can fly (up to 150 metres within its lifetime).
The COVID-19 pandemic has created an almost perfect storm for dengue to spread. Just like COVID-19, there is currently no effective way to cure dengue. And just like COVID-19 the solution to the pandemic is to stop its spread. Yes, you can learn how to prevent dengue.
How to Prevent Dengue, Stop the Breeding
To stop the spread of dengue, we need to stop mosquitoes from breeding. This is where we all have to play our part. As much as we would like to blame the empty construction yards, it is homes that form the bulk of mosquito breeding grounds. In a single dengue cluster in Singapore, 84% of homes were found to be breeding Aedes mosquitoes. It is up to every one of us to ensure that our homes, as well as common areas, do not serve as breeding grounds for mosquitoes.
NEA has an advisory with case data and recommendations. Learn how to prevent dengue by removing stagnant water around our homes by turning the pail, tipping vases, flipping flower pot plates, loosening hardened soil in pots, clearing the roof gutter and drains, and placing the Bacillus thuringiensis israelensis (Bti) insecticide inside such areas. Inside our homes, we can spray insecticide at dark corners, including under the sofa and bed, behind curtains, and in toilets, and use mosquito screen on windows. We can apply mosquito repellent or mosquito coils to protect ourselves from bites.
This article was contributed by Dr Tan Kok Kuan, a resident doctor at DTAP Clinic Novena.
Dr Tan Kok Kuan keeps abreast of developments in the medical world and participates at international Medical Conferences. His professional medical opinion is frequently sought after and he has contributed extensively to the local press. Dr. Tan is also active in community outreach; speaking on a variety of health topics to the general public as well as corporations.