Familiarity breeds contempt, as the saying goes, and with dengue being endemic in Malaysia, many seem to have grown complacent about the threat it poses.

Others are misled by half-truths and misinformation that create a false sense of security, leaving people vulnerable to the actual dangers of this mosquito-borne disease.

Dr Verna Lee Kar Mun, family medicine specialist at a private medical university in Kuala Lumpur, addresses five misconceptions, as follows:

1. With fogging, your worries are over

Yes, fogging in your neighbourhood kills adult mosquitoes, while getting rid of stagnant water in drains and other places helps prevent breeding sites.

But these measures are only partially effective, and also involve a lot of manpower and financial cost – to the tune of some RM777 million in 2009/2010.

There is even evidence that mosquitoes have grown resistant to the common insecticides used in fogging.

“The authorities are already testing new methods, such as the use of genetically modified mosquitoes in hotspots. And now, there is news of a vaccine being reviewed,” Lee shared.

None of this, she cautions, is an excuse to let down your guard. “All of us can help prevent mosquito bites and breeding sites. Remember, you can quarantine a person, but you can’t quarantine a mosquito.”

2. You only get dengue once

There are four dengue serotypes, which means a person can get infected up to four times. Total immunity is possible only if a person has been infected with each of the four strains.

However, before you start thinking about intentionally getting infected four times, bear in mind that each subsequent infection is likely to be more severe than the one before.

As severe dengue is a serious illness that requires hospitalisation and may lead to devastating consequences such as organ failure, repeated dengue infections are definitely the wrong way to go.

Also note that there is presently no cure for dengue, or any specific treatment that can help once you’ve been infected, not even antivirals.

3. As long as you don’t feel sick, you’re fine

There are three stages of dengue fever: firstly the febrile phase, characterised by one to two days of high fever that comes on suddenly. During this time, patients are likely to have body aches, headache with pain behind the eyes, flushed faces, and sometimes blotchy skin or rashes.

Next comes the critical phase. Ironically, this is when the fever subsides, and many people may feel they are getting better.

However, these next couple of days are when a patient can possibly go into shock if the capillaries leak plasma, leading to a sudden drop in blood pressure.

It is this phase that will determine if patients get better and proceed to the recovery phase, when they are able to reabsorb fluids and their platelet counts restabilise, or get worse.

“Many viral illnesses such as dengue are self-limiting, which means they will naturally subside,” Lee said. “The most important thing to remember is to take plenty of fluids to prevent dehydration that comes with plasma leakage.

“Anyone who gets dengue fever should aim to drink at least three litres of water daily for the first three days.”

4. Dengue is just a mild illness

While many people who get infected with dengue are able to recover at home, this does not mean it is nothing to worry about.

“An estimated 1% of patients will experience severe dengue, also known as haemorrhagic dengue, which will require hospitalisation,” Lee explained.

“Bleeding can begin in the febrile phase, usually in the skin or gums. If it is not managed well, the patient’s condition could worsen during the critical phase, which is when most people are admitted.

“Those with a healthy immune system usually recover in two days, but if there is inflammation affecting the organs such as the heart, liver or brain, it could take up to a week or longer if there are complications.”

For those with low blood pressure, the symptoms may begin earlier, while women who are menstruating may experience heavier bleeding.

Other signs of severe dengue include pain in the abdomen, persistent vomiting, rapid breathing, and blood in the vomit or stool.

5. You can only test for dengue after three days

It is true that initial symptoms can be vague, as fever can be indicative of many different illnesses. “But with dengue, the high fever usually comes suddenly, whereas with Covid-19, for example, the onset of fever is slower,” Lee said.

“The S1 dengue rapid antigen test can detect dengue from the first day, so don’t delay seeking medical advice if you suddenly develop a high fever.”

Overall, Lee reminds everyone to make a bigger effort to protect themselves and their loved ones. “Make sure your home environment is clear of any breeding sites; cover up exposed skin; and use mosquito repellents, especially during sunrise and sundown,” she concluded.