The rate of dengue infections in Malaysia this year is alarming. In the first three weeks, (epidemiological weeks) of the year, 7,058 cases were recorded – an increase of 226 per cent compared to 2,165 cases reported during the same period in 2022.
Three died due to dengue compared to zero deaths during the same period last year.
While Malaysia is finally recovering from the Covid-19 pandemic, the dengue threat remains a major public health hazard. Based on national data, the dengue trend follows a cyclical pattern, with an epidemic reported every four to five years.
The two recent dengue epidemics were observed in 2015 and 2019, with an average of 2,300 cases/week and 2,500 cases/week respectively. Given this cyclical trend, it is anticipated to peak in 2023.
Selangor is the worst-hit state. As of Feb 11 this year, it had 6,870 cases, an increase of 141.4 per cent compared to last year.
Because all four dengue virus (DENV) serotypes co-circulate in Malaysia, the country is hyper-endemic with dengue. That means people could get infected with dengue up to four times in their lifetime. Worse, being infected with one serotype does not give protection against the rest of the dengue serotypes.
Patients who acquire a second dengue infection with a different dengue serotype are at an increased risk of severe dengue, leading to shock, internal bleeding and even death.
According to deputy director of Health (Public Health) Datuk Dr Norhayati Rusli, the change in the dominant circulating dengue serotype or the “serotype shift” is a well-known reason for the occurrence of the dengue surge.
“It has been observed that dengue cases will usually increase four to six months after a serotype shift due to the lack of immunity in the community towards the new dominant circulating serotype.
“From the MoH’s surveillance monitoring, there was a shift of circulating dengue virus serotype from DENV 3 to DENV 4 since June 2021. Since then, DENV 4 serotype has been the dominant circulating virus serotype in the environment.
“Moreover, the opening of all sectors after the Covid-19 pandemic encourages population movement from dengue-prone areas to non-endemic dengue areas,
which will introduce the dengue virus to a ‘dengue naive’ population. Furthermore, urbanisation with increased population density will aggravate the spread of the dengue virus, especially in the densely populated area.”
Climate change, she said, was another important factor, especially with alternating rainy and hot seasons.
“During the rainy season, containers or natural places, such as leaves of plant,s will be filled with water, providing places for the Aedes to breed. During the hot season, the Aedes mosquito becomes more active in its biting behaviour and it bites more humans, thus increasing the spread of the dengue virus.”
“Poor environmental cleanliness with the abundance of man-made containers provides suitable places for Aedes mosquitoes to breed. Human habits and littering are the main reasons for poor environmental cleanliness.”
“Lack of cooperation from certain households for indoor mosquito control activities will limit the effectiveness of interrupting dengue transmission in the local community.
“The inadequate coverage of indoor mosquito control activities may result in prolonged dengue outbreak in the locality.”
Dengue outbreak after flooding is also a well-known phenomenon, as the stagnant water provides favourable conditions for mosquitoes to breed. The lag time is usually around three to four weeks before the occurrence of dengue cases.
Malaysian Medical Association (MMA) President Dr Muruga Raj said the public must ensure that their homes and surrounding areas do not turn into breeding grounds for the Aedes mosquito.
“There is no point in carrying out fogging every other month or so if people aren’t doing their part.”
Dr Norhayati added: “By and large, public apathy towards health initiatives by the Health Ministry, including dengue-related activities, remain insignificant based on the warm response from the community during nationwide community engagements and dengue promotional activities.
“Besides that, the ministry’s Health Education Division has mobilised a Special Health Education Team (PAKAT) to dengue hotspots to raise community awareness about dengue prevention towards searching and destroying Aedes breeding sites.”
Integrated enforcement is being coordinated by the Health Ministry and carried out monthly in various states.
Dr Tahir Aris, the director of the Institute for Medical Research (IMR), added that the iDengue website, an initiative of the MoH and Agency Angkasa Negara, now includes data on dengue hotspots, daily and cumulative statistics, and many other helpful public resources.
“It would benefit many researchers if the serotype statistics were available on the website. Information such as current locally commercialised dengue-related products and local research breakthroughs can also be included to raise public awareness,” said Dr Tahir.
According to Dr Norhayati, advocacy events also play an essential role in getting public support.
“For example, the commemoration of Asean Dengue Day on June 15 each year was endorsed by the 10th Asean Health Ministers Meeting in 2010.
“Last year, the theme for Asean Dengue Day was ‘Asean’s Resilience Against Dengue Amidst Covid-19 pandemic’. Malaysia launched the event in Malacca with activities to encourage community participation to keep the environment clean and reduce potential mosquito breeding places.”
Additionally, advocating for the community to become volunteers of MyCHAMPION, previously known as the Communication for Behavioural Impact (COMBI) group, is essential to ensure community ownership of dengue prevention and control activities.
“The main purpose of MyCHAMPION is to act as an agent of behavioural change in the local community and to mobilise the communities to ‘search and destroy’ Aedes breeding sites in their neighbourhoods, weekly. Behavioural change of Malaysians towards maintaining a clean environment will enhance the sustainability of dengue prevention in the community.”
She added: “National cleaning campaign activities (Gotong Royong Mega Perangi Aedes Peringkat Kebangsaan) have been implemented at the national, state, and district levels to mobilise residents, along with the relevant agencies, to get rid of Aedes breeding sites.”
“In 2022, the Health Ministry organised two national campaigns, 30 state campaigns and 54 district campaigns at various locations to engage with the local community. The National-level Gotong Royong Mega Perangi Aedes was held in Melaka in June 2022, and Pahang in October 2022, respectively.” – The Health
