Dengue case numbers to peak this year following cycle uptrend

PETALING JAYA: The rising number of dengue cases is part of a cyclical trend and is expected to peak this year, says Tan Sri Dr Noor Hisham Abdullah.

The Health director-general said this was based on national data, which shows that dengue trends follow a cyclical pattern with an epidemic being reported every four to five years.

“The recent dengue epidemics were observed in 2014 and 2019, with an average of 2,300 cases per week and 2,500 cases per week reported respectively.

“The rising number of dengue cases is partly contributed by the change in dominant circulating dengue serotype, or the ‘serotype shift’, which is a well-known reason for dengue surges.

“It has been observed that dengue cases will increase usually four to six months after a serotype shift due to the lack of immunity in the community towards the new dominant circulating serotype,” he said in a statement yesterday.

From the Health Ministry’s surveillance monitoring, there has been a shift of the circulating dengue virus serotype from DEN 3 to DEN 4 since June 2021, Dr Noor Hisham added.

Since then, the DEN4 serotype has been the dominant circulating virus serotype in the environment, he said.

In 2022, Malaysia reported 66,102 dengue cases with 56 deaths, compared to 26,365 cases with 20 deaths in 2021.

This was an increase of 150.7% in dengue cases and a 180% increase in deaths from the previous year.

Dr Noor Hisham said that other countries in the region are also seeing a rise in dengue this year.

In terms of contributing factors, he pointed out that human behaviour, such as littering, is among the main reasons for poor environmental cleanliness.

“The abundance of man-made containers (being littered) have provided suitable breeding places for Aedes mosquitoes,” he said, adding that climatic change is also an important factor, especially with alternating rainy and hot seasons.