KUALA LUMPUR: The Health Ministry (MOH) is looking at expanding the use of Wolbachia-infected mosquitoes to biologically control the spread of dengue in persistent hotspots in Selangor, Kuala Lumpur and Penang.
This follows the success of the programme which was introduced at six different sites earlier this year — AU2 Keramat, PKNS AU2 Keramat, Shah Alam Section 7, Flat PKNS, Jalan Plumbum 101/103 Shah Alam, Mentari Court and Pusat Komersial Section 7.
Health director-general Datuk Dr Noor Hisham Abdullah said these locations had previously had high levels of dengue transmission.
He said by using a strain of the bacteria Wolbachia, which inhibits mosquitoes from transmitting viruses to human, researchers at the medical entomology unit, Institute for Medical Research (IMR), MOH, together with the Universities of Glasgow (United Kingdom) and Melbourne (Australia) had successfully reduced the incidence of dengue at hotspots in the state.
Dr Noor Hisham said studies showed that mosquitoes carrying the wAlbB strain of Wolbachia, when released into the environment, had the effect of reducing the incidence of dengue cases by at least 40 per cent.
The Wolbachia carrying mosquitoes — both male and female — mate with the wild mosquito population, resulting in the spread and establishment of the virus-inhibiting bacteria.
He said at some sites, Wolbachia-carrying mosquitoes were measured at over 90 per cent frequency, more than a year after the mosquito releases ended
He said the data was published in the peer-reviewed journal, Current Biology, on Nov 21.
The paper, Establishment of Wolbachia strain wAlbB in Malaysian populations of Aedes aegypti for dengue control, was published in Current Biology and available at //www.cell.com/current-biology/fulltext/S0960-9822(19)31446-0.
The study was funded by the Wellcome Trust, National Health and Medical Research Council of Australia Awards and the MOH.
He said the success of lowering dengue cases at these sites had also led to a cessation in insecticide fogging in these areas, highlighting both the environmental and economic benefits of the biological method.
Besides dengue, the wAlbB strain of Wolbachia is also effective in blocking transmission of other mosquito borne viruses, including Zika and chikungunya, he said.
“Seeing the promising impact in the initial releases and impressed by the evident success of this trial, the MOH’s Disease Control Division together with IMR, National Public Health Laboratory, Health Education Division, Institute for Health Behavioural
Research, state Health Departments, district health offices, local authorities, state governments and communities were now using Aedes aegypti carrying Wolbachia operationally and extending this approach into different dengue persistent hotspots in Selangor, Kuala Lumpur and Penang.
He said previously scientists elsewhere had successfully carried out mosquito releases using a different strain of Wolbachia, but while this strain was effective in some conditions, it did not appear to be suitable for use in the hot tropical conditions experienced inMalaysia.
More than 100,000 dengue cases were reported in the country in 2016 with an annual cost estimated at RM729.7 million.
From Jan to Nov 16, this year, 114,745 dengue cases were recorded. This represents an increase of 48,175 cases (72.4 per cent) compared with 66,570 cases during the same period last year.
Severe disease occurs in around one per cent of cases, including life-threatening haemorrhage or shock syndrome.
In the absence of an effective vaccine and anti-viral treatment, the scourge of dengue is spreading rapidly globally.