A decade ago, in my previous capacity at the Indian Council of Medical Research (ICMR), we published a paper, “Dengue in Kerala: A Critical Review”, which highlighted the status of dengue fever in Kerala in the light of factors that have forced a sylvatic mosquito like Aedes albopictus to seek a new breeding habitat near habitation and facilitate transmission of dengue virus in a virtually non-immune population. Cut to 2016, where an article ( The Hindu , May 19) forewarns of the hyperendemic form that dengue may take in the State this year, posing a huge threat to public health.
Unfortunately, the prophecy has come true. This year, Kerala has recorded 4,060 dengue cases, the highest in the country. With a situation at hand in a State like Kerala, which has been acclaimed for having a well-coordinated and effective health-care system, highest life-expectancy, pride in personal hygiene and, above all, a near-universal literacy; it may as well be said that vector control in isolation is not enough to curb the growing incidence of dengue.
Sadly, Kerala is not battling dengue alone, making it essential for us to look at an integrated and comprehensive prevention and control strategy inclusive of an effective vaccine.
In recent decades, dengue is being reported in explosive proportions globally, bringing with it a substantial socioeconomic impact on individuals and society. The truth is that no drugs are available to treat dengue. Mortality from dengue still prevails in developing countries, forming a formidable threat to public health.
India has reported an annual average of 20,474 dengue cases (2006-12). However, it surged to 40,571 with 137 deaths in 2014. Last year, there were 100,000 cases and 220 deaths. Today, urban hubs like the national capital New Delhi, and State capitals like Kolkata and Bengaluru are struggling to fight the endemic form of dengue. India is bearing an estimated total annual economic cost of $1.11 billion due to dengue, which includes direct medical costs of $548 million.
Vector control Among the interventions for dengue prevention, vector control takes centre stage. However, community-level implementation of small interventions to prevent water accumulation in coolers, manhole lids, tyres and water tanks along with general cleanliness particularly in the urban areas are far from optimal. It is also observed that dengue mosquitoes are found inside homes; hence impregnating indoor curtains with insecticides such as Pyrethroid has proved efficacious.
A comprehensive strategy is deemed necessary due to absence of a specific antiviral therapy for treatment of dengue. Solitary vector control is unable to yield a satisfactory reduction in viral transmission, Therefore, these makethe implementation of a safe, efficacious and cost-effective dengue vaccine remains a high public health priority.
In the past decade, substantial progress has been made towards developing an effective dengue vaccine, which one candidate completing all stage of development. The vaccine by Sanofi Pasteur has been licensed after Phase III trials and approved by some national regulatory authorities. It has been introduced in Philippines and a few other endemic countries. The results are expected soon and keenly awaited. This candidate vaccine has also been recommended by SAGE, a WHO body which looks at various vaccines for infectious diseases. The vaccine against dengue at the moment can be used only for those between 9 – 45 years of age.
Similarly, the NIH vaccine made in Brazil by Butantan has been successfully tested in Brazil. Parallel evaluation is under way in Brazil and Mexico. Two Indian companies, the Serum Institute of India and Panacea Biotech, are also developing this vaccine. The Takeda vaccine has a promising design and undergone trials in Singapore and currently in the Phase III evaluation.
The World Health Organisation ((WHO) and Dengue Vaccine Initiative (DVI), an international consortium supported by the Bill and Melinda Gates Foundation — which formalises research, policy and advocacy with scientific evidence to fight dengue fever — have been working together in collaboration with vaccine manufacturers and national regulatory bodies to accelerate dengue vaccine development. The position paper on dengue vaccine by the World Health Organisation (WHO) released on July 29, 2016 comes as a significant step to expedite the availability of a dengue vaccinelike India.
In fact, WHO has recommended that countries should consider introduction of the dengue vaccine in geographic settings where epidemiological data indicate a high burden of disease.
Despite these promising efforts, a more comprehensive approach towards effective vaccine introduction, vector control techniques, robust and accurate surveillance, modelling studies, heat maps of global data and release of sterile mosquitoes need to be seriously taken into consideration.
N.K. Ganguly is the former Director General, ICMR. Dr. Mukhopadhyay is Senior Program Officer for Policy Centre for Biomedical Research.
Corrections & Clarifications:
The article had incorrectly carried a wrong photograph of Ms. Bratati Mukhopadhyay. The error is rectified.
