AEDES AEGYPTI CARRYING WOLBACHIA BACTERIA A BIOLOGICALLY VIABLE TOOL FOR DENGUE CONTROL

AIN FATIHA ABDUL KARIM
KUALA LUMPUR, Nov 22 (Bernama) -- Scientists have reported an effective and environmentally sustainable way to block the transmission of the mosquito-borne dengue virus, in field trials carried out in Malaysia. Wolbachia, a widespread bacterial symbiont of insects, has emerged as a viable tool to control Aedes borne diseases. 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), Ministry of Health Malaysia (MOH), together with the Universities of Glasgow (UK) and Melbourne (Australia) were successfully able to reduce cases of dengue at dengue hotspot sites in the state of Selangor. Their data, published on 21 November 2019 in the peer-reviewed journal Current Biology, shows 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%. Besides dengue, the wAlbB strain of Wolbachia is also effective in blocking transmission of other mosquito borne viruses including Zika and chikungunya. Previously, scientists elsewhere, have carried out successful 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 in Malaysia. In Malaysia, over 100,000 dengue cases were reported in 2016 with an annual cost estimated at USD 175 million. For 2019, the total number of dengue cases between January to 16 November 2019 reached 114,745 cases which is an increase of 48,175 cases (72.4%) compared to 66,570 cases during the same period in 2018. Severe disease occurs in around 1% 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 rapidly spreading globally. Researchers released batches of Aedes aegypti mosquitoes carrying the wAlbB strain of Wolbachia into the environment in 6 different sites initially, namely AU2 Keramat, PKNS AU2 Keramat, Shah Alam Section 7, Flat PKNS, Jalan Plumbum 101/103 Shah Alam, Mentari Court and Pusat Komersial Section 7 with previously high levels of dengue transmission. The Wolbachia carrying mosquitoes – both male and female – then went on to mate with the wild mosquito population, resulting in the spread and establishment of the virus-inhibiting bacteria. In some sites, Wolbachia-carrying mosquitoes were measured at over 90% frequency more than a year after the mosquito releases ended. The success of lowering dengue cases at these sites has led to a cessation of insecticide fogging in these areas, highlighting both the environmental and economic benefits of this method. 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 are now recruiting Aedes aegypti carrying Wolbachia operationally and extending this approach into different dengue persistent hotspots in Selangor, Kuala Lumpur and Penang. With sincere appreciation, we proudly recognise and honour the outstanding contributions of the members of the community in the trial sites, who with their dedicated efforts and generous cooperation helped to ensure the success of the project. The paper, ‘Establishment of Wolbachia strain wAlbB in Malaysian populations of Aedes aegypti for dengue control’ is published in Current Biology and available at https://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 Ministry of Health Malaysia. DATUK DR. NOOR HISHAM BIN ABDULLAH Director General of Health Malaysia 22 November 2019 SOURCE: Ministry of Health Malaysia FOR MORE INFORMATION, PLEASE CONTACT: Name: Baharudin bin Mohamad Ministry of Health Malaysia Tel: 03-88834536 / 017-2635008 --BERNAMA