Dengue is a disease that knows no boundaries. Countries have to be united to reduce the dengue burden, aptly echoed by this year’s ASEAN Dengue Day theme, United Fight against Dengue. Globally, dengue is estimated to affect 390 million individuals annually, mostly in the Western Pacific and South-east Asia regions.
The Aedes mosquito is a key risk factor for dengue transmission, and it is impossible to completely annihilate the mosquitos. Despite effective control measures in Singapore, still about 20 per cent of the population would be exposed to dengue by age 20. The three reasons inhibiting the complete eradication of Aedes mosquitoes are: the tropical climate being a perfect breeding ground, the mosquitos adapt well to the environment and control measures thus developing resistance to pesticides, and lastly, the prevalence of potential breeding grounds even with stagnant water as small as a 50-cent coin.
Early diagnosis is critical in dengue control. It alerts the relevant authorities and communities, raises awareness among primary care physicians to clinically diagnose for suspected dengue, and encourages the use of test tools to detect it more accurately. It also emphasises the importance of personal protection measures, such as avoiding dengue hot spots and applying mosquito repellent.
Community resilience is the key to mosquito control, but yet it is often neglected due to the lack of knowledge and clinical experience of primary care physicians, and of the community to adopt preventive measures.
Sustained community resilience, awareness and mobilisation against dengue remain paramount, despite the availability of a dengue vaccine and the use of Wolbachia bacteria-carrying mosquitoes.
The recent use of Wolbachia-carrying mosquitoes shows promise in reducing the mosquito population. The Wolbachia strain of bacteria inhibits the replication of viruses such as dengue in the mosquito, hence has less potential to transmit dengue to humans.
Within ASEAN, Singapore, Indonesia and Vietnam have started performing local trials to release Wolbachia-carrying male mosquitoes.
The world’s first dengue vaccine was launched in 2015 and, so far, 16 countries have approved it, including Singapore, for the 12 to 45 age group. Overall, the vaccine is effective in reducing 60 per cent of dengue. However, the vaccine’s long-term effectiveness needs further investigation as well.
Other challenges include its accessibility and availability, and the public’s awareness and acceptance of it. A high level of at least 70 per cent vaccination coverage is needed to limit dengue transmission effectively. These challenges re-emphasise the importance of educating local communities.
Global warming and globalisation facilitate dengue transmission. Global warming can increase the geographical presence, growth rate and frequency of blood feeding of these mosquitos. Whereas globalisation results in more people travelling across continents and this allows for continuous mixing of susceptible individuals among those who are infected, thus sustaining dengue transmission.
Sustained dengue outbreaks within and beyond the ASEAN regions will still inevitably occur, with the current limitations of the dengue vaccine and the use of Wolbachia-carrying mosquitoes.
Hence, more research is needed to improve community resilience and to guide whole-of-community initiatives. To win the battle against dengue, we must not let up in our community efforts, but be more aggressive.
Read more here.
Source: The Straits Times, 15 June 2017