Need to keep environs clean: Littering has been a major contributing factor in Aedes breeding, says Nga. Seen here is stagnant water at a dumpsite close to an apartment building in Cheras. — Filepic
PETALING JAYA: As dengue cases are expected to peak this year and fogging has not been as effective, experts say more has to be done to keep dengue under control.
Universiti Kebangsaan Malaysia’s parasitology and entomology expert Prof Dr Hidayatulfathi Othman said fogging was only effective in killing adult mosquitoes but unable to kill “immature” ones usually found in water.
“In a few days, those in the water will emerge and replace those killed. Thus, it will return to the original population if we do not search for and destroy the breeding habitats,” she said.
Mosquito control expert Dr Lee Yean Wang said conventional fogging was no longer effective in reducing the Aedes population due to behavioural changes in the species.
Commenting on the use of the Wolbachia method, Dr Lee said the project was still in the preliminary stages and could be very expensive as millions of mosquitoes were needed.
Meanwhile, Prof Dr Sazaly Abu Bakar of the Universiti Malaya Tropical Infectious Diseases Research and Education Centre said biological engineering should not be allowed in the ecosystem until it was proven that its benefits outweigh the potential risk of contaminating the mosquito’s genetic biodiversity.
“The long-term impact of the release of the Wolbachia-infected Aedes mosquito on the dynamics of the local mosquito population requires a better understanding.
“We currently have not done much research towards an understanding of our mosquito species’ genetics and their pathogen competencies,” he said.
On what is the most effective way to stopping the transmission of dengue, he said prevention was the way to go.
“The virus is spread from one infected person to the next through the bites of mosquitoes that have bitten and sucked the blood of the infected person.
“Hence, preventing an infected person from getting bitten by a mosquito is the only way to contain the spread of the disease.
“The government should consider allowing doctors to prescribe proven-effective mosquito repellent to all patients with acute dengue (dengue virus is in the blood only during the viremic phase) and allow the use of a self-test kit to detect dengue antigens early so that preventive use of repellents can be instituted faster.
“Dengue fever, while debilitating to suffer from in general, does not result in mortality, but severe dengue is a problem that needs much attention.
“Severe dengue is often the result of immune responses to a subsequent infection with a different dengue virus serotype; hence, knowing one’s dengue immune status would help one be better prepared,” Prof Sazaly added.
He said the government should also fund more serious research to study the factors influencing the outcome of dengue fever, prevention measures, the mechanisms that lead to severe dengue and treatment measures.
These studies must also cover the factors that enable the mosquitoes to survive during non-outbreak periods, factors that influence the mosquito biological vectors and behaviours influencing transmission of the virus from and to humans, and ways to do away with the use of pesticides and biological engineering of the ecosystem to control mosquitoes, he added.
A total of 31,111 dengue cases have been reported between Jan 1 and April 9.
As of April 2, 18 people had succumbed to the virus.
Health director-general Tan Sri Dr Noor Hisham Abdullah said in January that the number of cases was expected to surge in 2023 based on a cyclical pattern, while Deputy Prime Minister Datuk Seri Dr Ahmad Zahid Hamidi said last month that dengue cases in the country saw a massive 223% spike in the first quarter of the year compared with the same period last year.
