Turning to nature to fight dengue
PETALING JAYA: A nature-based method of controlling the spread of the dengue virus has shown to be the most effective strategy in curbing dengue fever, says an expert as the scourge surges worldwide and medical authorities bank on new vaccines and drug treatments.
World Mosquito Programme CEO Scott O'Neill said there is strong evidence in trials conducted in Indonesia showing the Wolbachia method has been the most cost-effective and sustainable way at tackling the virus by preventing its spread in the first place.
'High-quality clinical trials have shown that it can be highly effective, with a large trial in Indonesia showing a 77% reduction in cases and an 86% reduction in hospitalisations once deployed,' O'Neill told The Star in an interview.
According to the World Mosquito Programme's website, the method involves releasing mosquitoes infected with the Wolbachia bacteria into the local mosquito population.
The bacteria blocks viruses such as dengue, chikungunya and zika from growing in the bodies of Aedes aegypti mosquitoes, thus reducing the insects' ability to transmit these viruses to humans.
'When Wolbachia is established in a mosquito population it results in a decreasing incidence of dengue, zika and chikungunya,' the website said, adding that the bacteria is safe for humans and the environment.
Malaysia has also adopted this strategy by setting up 34 sites to release Wolbachia mosquitoes in Selangor, Johor, Penang, Kelantan, Melaka, Pahang, Kuala Lumpur and Putrajaya.
Last year marked one of the deadliest on record for dengue, with over 14 million cases and more than 10,000 dengue-related deaths worldwide, as reported by the European Centre for Disease Prevention and Control.
In Malaysia, the Health Ministry reported 122,423 dengue cases and 117 deaths in 2024, a slight decrease from 123,133 cases and 100 deaths in 2023.
Alarmingly, from Jan 1 to June 19 this year, there have been 29,717 cases recorded, with Selangor accounting for nearly half of these with 12,749, based on the ministry's iDengue site.
This is followed by Kuala Lumpur with 3,972, Johor (3,265), Sabah (2,081), Negri Sembilan (1,946), Kedah (1,218) and Perak (1,072).
At present, there are 280 active outbreak localities and 16 deaths have been recorded as of June 15.
O'Neill is doubtful that the rollout of new dengue vaccines could be the silver bullet against the disease.
'The first vaccine had worrying safety signals when administered on those who did not have dengue before, while the second has only been evaluated in two of the four dengue serotypes.
'Both of these vaccines require multiple carefully spaced shots to be effective. Given the efficacy of current vaccines and the challenges of administering them in a public health programme, they are unlikely to represent a solution for diseases like dengue by themselves.
'They will be a useful tool, though, to contribute to dengue control together with other approaches,' he said.
Last year, Malaysia's Drug Control Authority approved the first dengue vaccine for use in the country named Qdenga.
The vaccine is said to protect against all four dengue virus serotypes.
It is particularly effective against the serotype-2 virus (DENV-2), which is currently the dominant viral strain in Malaysia.
O'Neill also does not see repurposing drugs to treat dengue as a promising strategy.
'While a lot of work has been done on the possible use of antiviral drugs to treat dengue, the problem is that most patients seek care too late after the disease has progressed for the drugs to be effective,' he said.
Health Minister Datuk Seri Dr Dzulkefly Ahmad recently revealed that repurposing drugs to treat dengue is one of Malaysia's latest approaches to fight the disease.
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