What is a vector-borne disease?

A vector borne disease is one that is transmitted to humans via insects.

For example, dengue or malaria are borne by mosquitoes, which get infected by biting humans who carry the virus and, in turn transmit the disease to healthy humans by biting them. Mosquitoes know no borders and typically thrive in a warm, humid environment, which means climate change may help them spread to new countries.

The dengue vaccine takes another step forward

Asia has been endemic for dengue for some time. And by following the World Health Organization (WHO) guidelines, Asian countries have made some significant advances in the fight against the disease. Indonesia, for example, has reduced its case fatality rate from 41% in 1968 (when dengue was first reported) to 0.9% in 2013.
But despite the improved case management, integrated vector control and community participation, the incidence of dengue across Asia is still too high, and spreading very fast.

Eagerly awaiting a dengue vaccine

Prof Sri Rezeki Hadinegoro, paediatrician and senior lecturer at the Dr Cipto Mangunkusumo hospital in Jakarta, hopes the introduction of a dengue vaccine will dramatically reduce the incidence and mortality of dengue across Asian endemic countries. “We are eager to add it to our dengue control and prevention strategy here in Indonesia,” she adds.
The long awaited dengue vaccine has recently made a gigantic leap closer. The analysis into the efficacy and interim long-term safety of Sanofi Pasteur’s dengue vaccine candidate has been made available. Published in The New England Journal of Medicine with the title “Efficacy and Long-Term Safety of a Dengue Vaccine in Regions of Endemic Disease” (Hadinegoro et al.), the study pools and analyses data across three clinical trials in dengue-endemic countries within the Asia-Pacific and Latin America.

CYD14 Indonesian Study Team, image courtesy of Prof Sri Rezeki Hadinegoro

CYD14 Indonesian Study Team, image courtesy Sri Rezeki Hadinegoro

93.2% protection against severe dengue

As one of the study’s authors, Prof Hadinegoro discussed its results with us. “The pooled study results showed consistently higher efficacy for preventing symptomatic dengue and an acceptable post-vaccination safety profile for individuals aged nine and older,” she reveals. “For this age group the results showed the vaccine provided 65.6% protection against symptomatic dengue of any severity and 93.2% protection against severe dengue. They also showed that it prevented 80.8% of dengue hospitalizations during the 25-month follow-up period.”
Prof Hadinegoro explained the importance of protecting the pre-adolescent to adult population in dengue endemic countries: “The older age groups – of nine years old and above – represent a significant segment of the population experiencing the bulk of dengue cases. The candidate dengue vaccine is expected to provide a positive public health impact on dengue disease burden in these individuals in dengue-endemic areas – contributing to WHO objectives to decrease dengue-related mortality by more than 50% and morbidity by more than 25% by 2020.”

Vaccination, image courtesy of Prof Sri Rezeki Hadinegoro

Vaccination, image courtesy, Sri Rezeki Hadinegoro

Ongoing surveillance

The results amongst the younger trial participants were not so spectacular. Efficacy among children younger than nine years was much lower at 44.6%, with 44.5% protection against severe dengue, and 56.1% of dengue hospitalizations prevented. Prof Hadinegoro notes: “Additional surveillance data is needed to provide more information on the overall impact of the vaccination in children in this younger age group.”

Physical examination before vaccination, image courtesy of Prof Sri Rezeki Hadinegoro

Physical examination before vaccination, image courtesy of Prof Sri Rezeki Hadinegoro

She also highlighted that it was important to continue the long-term safety follow-up of the vaccines in the most recent phase three trials.
Another important role played by surveillance – this time during the trials – was in highlighting the under-reporting of dengue cases. Active surveillance during the clinical trials allowed the study teams to confirm the magnitude of under reporting of dengue cases in each participating country. “This highlights the importance of having a good surveillance system in place in each country,” adds Prof Hadinegoro.

The long road ahead

Once the vaccine becomes available, each country must embark on a journey of potentially several years before reaping the benefits of the vaccine. Prof Hadinegoro notes that the most important step will be approval of the vaccine by the National Regulatory Authority in that country. She comments: “Only after the vaccine has been registered and licensed can it go to the market.”
Regulations will be needed before the vaccine can be introduced into national immunization programs. “These regulations will depend on the plan from the Ministry of Health, Ministry of Finance, and Parliament,” reveals Prof Hadinegoro. The first market to use the vaccine once it becomes available will be the private sector, she believes. Unfortunately, it only covers around 10% of the target population. Prof Hadinegoro concludes our discussion by expressing her hopes that the Indonesian government will accept this dengue vaccine and introduce it into a national program faster than other vaccines to help achieve the goal of reducing mortality and morbidity by 2020.
Do you think the dengue vaccine will allow us to win the fight against the growing burden of dengue? Share your thoughts with us!

About Prof Sri Rezeki Hadinegoro:
Prof Sri Rezeki HadinegoroProf Sri Rezeki Hadinegoro has been a paediatrician and senior lecturer at Department of Child Health, Division of Infection and Tropical Pediatrics, Faculty of Medicine, University of Indonesia, Dr Cipto Mangunkusumo hospital in Jakarta since 1983. She has since taken an active role in dengue control at the hospital, and the Indonesian Ministry of Health. She has been actively managing the Immunization Task Force at the Indonesian Pediatric Society for 15 years, supporting the government’s national immunization program. The Ministry of Health promoted her to chairman of the Indonesian Technical Advisory Group on Immunization (ITAGI).
In 1996 Prof Hadinegoro earned a PhD from the University of Indonesia, studying “The role of endotoxin in Dengue Hemorrhagic Fever, with focus on cytokine activation”. The university promoted her to professor in 2000. Today she is chairman of the Pediatric Research Center at the Department of Child Health in the university’s hospital. She also gives lectures at many hospitals around Indonesia and has written books for doctors on diagnosing dengue.

Spreading dengue fever: Tales of a well-travelled virus

Spreading dengue fever is easier than ever before. Dengue may be new to many parts of the world, but is not a new disease to most. In fact, dengue fever first got the eyes of health authorities back in the 1950s when outbreaks raged throughout Southeast Asia. Since then, the virus has made its way around. The scary thing is that the virus became a global health problem in only a matter of decades.

Dengue travels well, and easily. Since the 1970’s the world’s fastest growing vector-borne disease has spread its reach from only being found in nine countries in tropical regions, to having a presence in over 120 tropical, and non-tropical countries worldwide.  With more than 1/2 of the global population at risk, many may ask… How can dengue spread so quickly, putting vast amounts of the global population at risk over such a short time-period?

Check out our comic below and see just how easy spreading dengue fever can be.

Is low-cost travel spurring dengue outbreaks?

Image of a comic that shows various ways of spreading dengue fever while traveling.

Are you carrying an extra passenger?

Click here to learn more about the true costs of dengue 

United against dengue at UN Headquarters

Student leaders break the silence on dengue at the UN

I attended the 7th Annual Millennium Campus Conference (MCC) at the United Nations Headquarters in New York, organized by the Millennium Campus Conference. This annual conference gathers some of the brightest university student leaders from over 50 countries, all of them highly interested in solving some of the most pressing development problems around the world.
The event was particularly important because the main topic targeted the new Sustainable Development Goals (SDGs), and the young people’s input on their implementation. For Break Dengue, this was the perfect time to share our global campaign against dengue, a disease that the international community aims to end by 2020. Young leaders at the conference helped raise awareness by bursting a balloon, as a symbol of “breaking the silence” on dengue disease control.

MCC15 delegates getting ready to break the silence on dengue

MCC15 delegates getting ready to break the silence on dengue

The importance of the SDGs for the Break Dengue community

One of the main outcomes of the Rio+20 Conference was the UN Member States agreement on launching a process to develop a set of SDGs, which will build upon the Millennium Development Goals (MDGs), focusing on the post-2015 priority areas for the achievement of sustainable development. In practical terms, the sustainable agenda moved to focusing on 17 concrete SDGs, to be achieved by 2030.
During MCC15, Dr. Jeffrey Sachs (@JessDSachs), Director of The Earth Institute and Special Advisor to the UN Secretary-General on the MDGs, pointed out that “we are at the start of the age of sustainable development and we have to start doing things differently.
The third and sixth SDGs are directly related to Break Dengue’s global cause: they focus on health and well-being for all, and on ensuring access to water and sanitation for everyone. The event therefore allowed us to highlight that dengue – the fastest-growing mosquito-borne disease, which has the potential to impact up to 40% of the world’s population – needs to be specifically targeted within that goal, similarly to malaria, tuberculosis and polio, in order to achieve sustainability.
From the perspective of the international community, the momentum around the SDGs brings forward the fact that dengue is also directly related to other sustainability issues such as access to clean water and sanitation (as dengue mosquitoes thrive in stagnant water), as well as climate change (as temperature rises, dengue may become more prominent). Neglecting dengue means neglecting our sustainable future, outlined in the UN goals.
During the MCC15, I had the great opportunity to personally meet Mr. Mogens Lykketoft (@Lykketoft), President-Elect of the 70th session of the United Nations General Assembly, and former Minister of Denmark. He joined us at the event, recognizing our efforts in achieving the SDGs as young people. I got the chance to chat with him about our online community as a tool to join forces in defeating dengue. He was happy to support us by holding the Break Dengue balloon as a symbol of breaking the silence.
In his speech to all delegates, Mr. Lykketoft acknowledged the great responsibility of young people in the sustainable development agenda of 2030, emphasizing the importance of a “pragmatic and action-oriented outcomes” when it comes to solutions and innovations in the sector.

President-Elect Lykketoft supported our initiative on breaking the silence around dengue

President-Elect Lykketoft supported our initiative on breaking the silence around dengue

Other interesting dengue-related initiatives led by young people

One substantial part of the event was the opportunity to meet other organizations and campaigns working on global health issues.
The END7 (@END7) campaign of the Global Network for Neglected Tropical Diseases aims to end several neglected tropical diseases (NTDs): whipworm, hookworm, roundworm, trachoma, river blindness, elephantiasis and schistosomiasis. These diseases infect over one billion people worldwide.
The Global Brigades (@GlobalBrigades) is the largest student-led social responsibility movement, working in four developing countries to resolve global health and economic disparities. They run education campaigns on dengue prevention in different communities.
Undoubtedly, the MCC15 was the perfect opportunity for young people who share a passion for sustainable development to see how they can change the world. On our side, we are breaking the silence around dengue, believing that together we can bring change. You can help us by signing our online petition.
Our special thanks goes to all the people who supported Break Dengue during the MCC15 at the United Nations in New York.
Read more about the MCC15 participants’ sharing the struggles of their communities as well as the testimonial of Colombian delegate Gabriel, who managed to overcome dengue.

What we could do better when it comes to vector control

Malaysian Public Health Entomologist in vector control Dr. Moh-Seng Chang talked about how little vector control has changed since the 70s. In this article, he shares what he feels could be done better when it comes to fighting outbreaks of dengue fever and other diseases like Zika and chikungunya spread by the Aedes aegypti mosquito.

“Local authorities should be handed the responsibility for house inspections, education, law enforcement, use of insecticides, and community mobilization…”

Image of Kuala Lumpur, a city in Malaysia struggling with vector control and dengue outbreaks
Doing it better 

Dr. Chang has some clear views on how things could work better. “Local authorities should be handed the responsibility for house inspections, education, law enforcement, use of insecticides, and community mobilization,” he tells us. Central government agencies would provide technical help and operational research support.

This would work better because:

  • Resource allocation is more effective at a local level where the manpower and equipment actually is.
  • Vector control can easily be incorporated into basic sanitation, rubbish collection, and other environmental programs already run by the local authorities, making dengue prevention and control more sustainable.
  • Many of the sites where the mosquitoes are harbored and active during the peak biting hours of the day – such as public parks – are already owned and managed by the local authority.
  • Community mobilization and interagency involvement are more effective with community leaders and villagers more closely associated with the local authority.

Dr. Chang also stresses the need for the involvement of the private sector. He gives an example of a recycling opportunity. A tire recycling plant would significantly reduce the number of abandoned automobile tires and the stagnant water breeding grounds they hold. “Private sector involvement is needed to provide the investment required for buying the machines for breaking down the tires and for creating the new materials,” he says.

Proper evaluation vital to success  

At a time when many vector control programs run in isolation without involving other relevant organizations, Dr. Chang agrees that integrated vector control management is the way forward.

He highlights the importance of good planning and management. “Integrated vector management needs good planning that spells out the details of who, how, when, and where. The communities and other sectors involved will need to clearly understand their roles, which must be relevant to them to ensure they maintain their commitment. Coordination and better program management are the keys.”

Vector control tools, and options need to be scientifically sound. Transmission sites and seasonality, community perception and acceptance, and insecticide susceptibility level, among many other things, need to be understood. Without proper evaluation upfront and monitoring along the way, vector control programs risk failure.

Vector control

Image courtesy of Dr. Chang

Dr. Chang believes too many community vector control tools developed are abandoned after a short period of time simply because they don’t take the desires and behaviors of participants into account. “If they are going to accept and contribute to a vector control operation, communities and participating agencies need to be interested and willing to take ownership,” he comments. “For this they need to both understand and benefit from it.”

A way forward  

There are some key steps that Dr. Chang believes we should be taking to prevent dengue outbreaks now to improve the situation:

Improve disease surveillance

Make low cost, rapid test kits more widely available to ensure dengue cases are discovered and reported quickly. Early diagnosis and treatment prevents death, while early notification enables emergency vector control to be initiated – meaning outbreaks are more likely to be contained.

Enhance environmental management and sanitation 

Encourage recycling schemes for plastic containers along with environmental maintenance and cleaning programs. Ensure contractors on green projects understand the implications for dengue and minimize the risk.

Plan for the vaccine

Understand how it should be used and how it can be delivered to the wider community. But even with the vaccine, prevention and vector control still has a role to play. The two should work together in parallel.

Evaluate new techniques

New innovations are emerging. We need to understand the role they will play and how they can be incorporated with on-going initiatives.

  • Genetically modified mosquitoes
  • Mosquitoes infected with Wolbachia that blocks dengue transmission
  • Attractants that lure the female mosquito to lay eggs, then kills them
  • Insecticide-treated screens and materials that form toxic resting sites

Furthermore, Dr. Chang is working on gaining a better understanding of the relationship between urbanization and dengue; on understanding the impact of development and changes in vector ecology. He’s also on the lookout for other potential Aedes mosquitoes that could potentially transmit dengue as ecology changes.

“Today, dengue prevention and control is solely relying on vector control and the programs have a long way to go. In any vector control program, monitoring and evaluation should be an integrated part of vector control elements. Vector control tools used should be integrated, evidence-based, use community approaches, and must be preemptive – anticipating outbreaks. Even when the dengue vaccine becomes operationally available in the near future, vector control programs will still have a role to play,” concludes Dr. Chang.

Furthermore, Dr. Chang is working on gaining a better understanding of the relationship between urbanization and dengue; on understanding the impact of development and changes in vector ecology. He’s also on the lookout for other potential Aedes mosquitoes that could potentially transmit dengue as ecology changes.

Dengue prevention and control is solely relying on vector control and the programs have a long way to go. In any vector control program, monitoring and evaluation should be an integrated part of vector control elements. Vector control tools used should be integrated, evidence-based, use community approaches, and must be preemptive – anticipating outbreaks. Even when the dengue vaccine becomes operationally available in the near future, vector control programs will still have a role to play,” concludes Dr. Chang.

Click below to join Dengue Track and put your data to work.


How well do you know dengue? Take our quiz!

ThinkstockPhotos-475326870With so many myths about dengue, isn’t it time to set the record straight? We need your help to share the facts and dispel the myths.

But do you really know dengue as well as you think you do? Take our dengue quiz to find out.

Vector control: Little changed since the seventies

image of Dr. Chan, vector control expert at work.

Image courtesy of Dr. Chan

Managing tomorrow’s disease using yesterday’s methods

The time for improving vector control to prevent dengue outbreaks is now. “Dengue is the disease of the future,” comments Malaysian Public Health Medical Entomologist Dr. Moh-Seng Chang. “And it’s going to become more and more of a global health problem as international travel, urbanization, and transportation increase.”

With more than 40 years working in dengue vector control (which is one of the methods of dengue prevention), Dr. Chang has seen little advancement. He firmly believes that better evaluation, monitoring, and management are the keys to improving the outcome of vector control interventions. We spoke with him about vector control and his experiences in the last 40 years.

Dengue vector control in the 1970s

The year 1975 saw the US Watergate scandal, the manned American Apollo spacecraft, and the manned Soviet Soyuz spacecraft orbiting, and the last naturally occurring case of smallpox.
1975 - Metal number.It was also the year after a major dengue epidemic in Malaysia and other Southeast Asian nations; and the year when Dr. Chang started work as a medical entomologist at the Ministry of Health in Sarawak, Malaysia. Back in 1975, Dr. Chang had studied the mosquito vectors but, like many people knew very little about vector control operations.

Then, like now, there were two main sides to dengue vector control:

  1. Breeding site reduction Governments were using radio, TV, newspapers, and leaflets to broadcast the call to clean up and to manage water storage. But their methods were falling on deaf ears. Unengaged, communities failed to act.
  1. Chemical control: mounted on trucks or using fogging and larvicide Insecticide sprays weren’t reaching the inside of homes where mosquito vectors were latent and people, especially children, were found resting during the day. Vector mosquitoes simply built up resistance to common insecticides use – and continue to do so today. And the use of insecticides for larval control simply failed because there were too many cryptic breeding sites around and many of them couldn’t even be found during house inspections.

These vector control methods were not sustainable. One of the key problems, then and now, was that they were not properly evaluated or monitored. “The trucks continued spraying areas even after mosquitoes had built up resistance or were spraying in the wrong areas at the wrong times,” recalls Dr. Chang. “To be sustainable and effective, dengue vector control programs should be community-based. Dengue control programs must first evaluate each method’s suitability and acceptability, and then monitor its effectiveness over time. Dengue control needs to be preemptive – it needs to be implemented before outbreaks actually happen.”

Evaluation of larval and adult mosquito densities during the post-spraying operation was almost non-existent at that time – and still today. It’s not surprising that teams fighting dengue fever continue to spray insecticide without any thought as to whether they were actually having an impact.

Cheap, simple and accepted

Over the years Dr. Chang has come across some often quite simple vector control interventions that have worked well and recommended them for further field evaluation on a larger scale:

  • Encouraging farmers to cut the ends off the cocoa pods they split in half during harvesting not only stops the pods from filling with water; it makes it easier for the farmers to extract the cocoa seed.
  • Adding two guppy fish to water storage tanks or cement jars ensures any mosquito larvae are eliminated – eaten by the predacious fish – before they have the chance to mature. The guppies live for more than a year.
Image of vector control examining potted plants for mosquito eggs

Image courtesy of Dr. Chang

  • In certain rural areas, where water supply is a problem and communities have to depend on rainwater from the roof, selling water tanks with a mosquito-proof cover stops the mosquito breeding cycle in its tracks. If a mosquito lays any eggs on the cover or in the roof gutters, they cannot fall into the water tank, while any mosquitoes that do mature within the tank cannot escape through the net.

These vector control methods worked because they were cheap, simple, and well-accepted by the community: they were sustainable. Another method, which didn’t work quite as well, was a program providing covers for smaller round water jars.

The netting covers were expensive and didn’t last long enough – less than a year in fact – making them too costly. “If the community could make the covers themselves or if the private sector became involved and came up with a cover that could be sold, with the jars at an affordable price, it would make this method much better,” adds Dr. Chang.

Image courtesy of Dr. Chang

Dr. Chang has some clear views on how things could work better. Check out our next article, to find out more…

Can we win the battle against mosquitoes?

August 20 is World Mosquito Day

World Mosquito Day, a perfect time to take stock of mankind’s ongoing battle against mosquito – one of our most deadly foes.


Mosquitoes spread diseases such as malaria, dengue fever, Japanese encephalitis, West Nile virus, chikungunya, and yellow fever. Malaria alone kills around 600 million people every year, most of whom are African children.

With climate change, these diseases are traveling to more areas and affecting more people than ever. Dengue fever, for example, will affect around 390 million people this year, mostly in the least developed countries on earth.

What is World Mosquito Day?
In 1897, a British doctor named Sir Ronald Ross made a discovery which ultimately led to smarter ways to prevent dengue fever – even if that wasn’t his primary intention at the time.
It was Ross who found that female mosquitoes (of the Anopheles genus) were to blame for transmitting the malarial parasite. And he won the Nobel Prize for Physiology or Medicine in 1902.
Since then, his discovery has been celebrated on August 20 every year – World Mosquito Day.

But this year, there is reason to be cautiously optimistic that the tide may be turning our way. The new vaccine should help turn things for the better and it will be one more tool that will help with the management of mosquito-borne diseases.

New vaccine

Last month, the European Medicines Agency (EMA) approved the first ever malaria vaccine. While the vaccine is not effective in all cases, it is a major breakthrough. Malaria kills 1,200 children per day. Even if the new jab only protects a fraction of those at risk, the potential for saving lives is enormous.

As recently as a decade ago, leading scientists believed that malaria vaccines would remain elusive. Now, a game-changing vaccine has the green light from regulators and researchers continue to work on other malaria vaccines too.

So what about dengue fever? Well, the first dengue vaccine is on the way. A new paper published in the New England Journal of Medicine (NEJM) shows lower rates of dengue-related hospitalization among children.

Experts say there are still a few more hurdles for the vaccine to clear before it is recommended for use but it is looking likely that by next World Mosquito Day there will be a dengue vaccine. But we mustn’t forget that a coordinated and integrated approach to addressing these diseases is necessary. After all, mosquitoes don’t stop at borders.

Read what the WHO has to say about dengue vaccine development.

Outwitting vector-borne diseases

ThinkstockPhotos-152127228Dengue is spreading fast

It’s clear we have to do more – and soon. But how can we when resources are already stretched beyond the limit? When we’re also fighting malaria, chikungunya, and a whole wealth of other vector-borne diseases?

To shake away these diseases we’re going to have to outsmart them. We’re going to have to take whatever tools we have and target them where they’ll have the greatest impact on all of them.

A plan of action

To make this work we’ll need a plan of action, and a clear picture of what diseases and vectors needed to be tackled and where.

The World Health Organization (WHO) has just the plan. Known as Integrated Vector Management (IVM), it’s a completely new approach to vector control that will help countries use the tools and resources they have at their disposal to tackle multiple diseases simultaneously.

Take for example insecticide-treated nets. Have you ever considered how they do more than just protect against malarial vectors? They also provide protection from dengue and a host of other vector-borne diseases. They’re just one small example of protecting people against a number of vector-borne diseases in one fell swoop. Smart, right?

But IVM isn’t just about using one tool to combat multiple diseases; it’s also about using multiple tools and resources against each vector and disease. It shows how, by sharing resources and expertise, the health, agricultural, and education sectors can control vectors more effectively.

A toolkit to guide you through

IVM transforms traditional vector control. It makes it more evidence-based, more integrated and more participative. It will lead to changes in roles and responsibilities as the health sector and local government build new links with other sectors and local communities. In essence, it requires a very different way of working and a different way of thinking, and that isn’t always easy.

So, to help, the Bill & Melinda Gates Foundation is funding a collaboration between WHO and Durham University to produce a series of IVM toolkits. These practical guidebooks – there will be one focused on the sub-Sahara and Africa, one on the Americas, and one on Asia – will provide the detailed information countries need to plan and implement IVM in their own specific situation.

The toolkits aren’t quite ready yet, but they will be ready for next year (they’re due to be published by the first quarter of 2016). They’ll include everything from suggestions on setting up organizational structures for deciding who does what among the public and private sector and community organizations to maps of where up to 10 different vector-borne diseases and their vectors are present. They’ll also explain which tools are effective in the control of each vector.

And there’s more. The toolkits will also help with vector surveillance and monitoring disease progression, which, in turn, will help countries measure the effectiveness of IVM.

Communities are the key to IVM success

ThinkstockPhotos-470801532Health, education, and government organizations will struggle to maximize IVM’s value if they don’t work with the support of local people. In fact, communities play some of the most crucial roles in IVM, by helping identify where the vectors are and the impact they’re having.

If applied with a collaborative and widespread approach, WHO believes IVM will improve outcomes and save lives. With governments, organizations and communities working together, do you think we can outsmart vector-borne diseases? Share your thoughts with us and join the Dengue Tribe!