What is Dengue
Dengue is the most common and most rapidly spreading mosquito-borne viral disease in the world. This global public health problem has grown in alarming proportions, with dengue infections increasing 30-fold in the last 50 years.
Four DENV serotypes
Dengue is caused by 4 distinct virus serotypes (DENV-1, DENV-2, DENV-3, DENV-4). Each serotype confers lifelong protective immunity only to itself, and infection with one serotype does not give long-term protection against the others. As a result, a single individual may be infected up to four times during in his lifetime. Sequential infections put people at greater risk for dengue hemorrhagic fever and dengue shock syndrome, the severe and potentially lethal forms of the disease.
An estimated 500,000 cases of dengue hemorrhagic fever and 20,000 deaths occur annually, mostly among children.
Who is at risk?
Dengue is transmitted by mosquito bites. There are two different vectors : Aedes aegypti and Aedes albopictus (better known as tiger mosquito). Nearly half the world’s population is at risk of infection. Prevalent in tropical and sub-tropical regions of the globe, dengue is endemic in more than 120 countries. The virus is spreading to regions where it had not been seen before, and from urban to rural settings. The economic and social burden of dengue is especially high in developing and emerging countries, which are hardest hit by the disease.
What is the best strategy to control dengue?
Currently, there is no specific treatment for dengue. Efforts to check the disease through conventional vector control alone have been only partially effective.
Many new tools for dengue prevention and control are being developed. However, it is clear that no single approach will succeed if used alone. Vaccination will not provide a “magic” solution. Scientists and public health officials agree: we must combine established methods with new tools to develop creative solutions. An integrated approach is the most likely path to success:
- synergies between a dengue vaccine, once available, and control of the mosquito vector could lower the force of infection and increase the impact of a vaccine
- multiple solutions and stakeholders must come together to achieve sustainable control of dengue
What has caused this upsurge?
Our modern world is characterized by a combination of factors that contribute to the rapid rise in dengue infections:
- population growth
- environmental changes: urbanization, different lifestyles
- global transportation
- greater movement of people, animals and goods as well as pathogens
- lack of effective mosquito controls
- no vaccine until today
Why has it taken so long to develop a vaccine?
Scientists began working on a vaccine over 60 years ago, but several challenges stood in the way of its development. First, it must prevent all four serotypes of the virus and secondly, there is no animal model to guide research.
But things are changing quickly. We are now entering an exciting era in which several vaccine candidates are in the pipeline and the very first dengue vaccine has just been licensed in Mexico, the Philippines and Brazil.
- 3.6 billion people at risk
- 400 million people infected each year
- More than 2 million people develop severe dengue (90% of them children under age 15)
- 20,000 deaths a social & economic burden
- No treatment no effective method of prevention
- 120 countries where dengue is endemic
- 30-fold increase in the incidence of infections over the last 50 years
- 9 billion dollars global economic burden