Small Bite, Big Threat: Vector-Borne Diseases in Asia

On World Health Day 2014, we focus on vector-borne diseases like dengue, malaria and lymphatic filariasis that are threatening the lives of millions across Asia and the Pacific.

Date: 07 April 2014

  • How can countries work together to fight the spread of malaria or dengue?
  • How can people protect themselves and their families from them?
  • What can be done to give these illnesses the attention and funding they need to be eradicated?

Karen Palmer: I’m your moderator, Karen Palmer, and today we’re marking World Health Day by speaking with experts from the World Health Organization and the Asia Pacific Leaders Malaria Alliance about how to promote greater vigilance and action in tackling a range of vector-borne diseases such as malaria, dengue, chikungunya, lymphatic filariasis, and schistosomiasis.

With me is Dr. Eva-Maria Christophel, Team Leader of Malaria and other Vector-borne and Parasitic Diseases at the WHO's Western Pacific Region, where she focuses on clinical and treatment aspects of malaria and other parasitic diseases.

Dr. Rabindra Abeyasinghe is Regional Entomologist with WHO’s Western Pacific Region. He has nearly 25 years of experience in malaria control including clinical management, parasitology, entomology, vector control and program management.

And finally, Dr. Ben Rolfe is Executive Secretary ad interim at the APLMA, the secretariat of which is hosted by ADB. Formerly Pacific Lead Health Advisor at the Australian Department of Foreign Affairs and Trade, Dr. Rolfe has more than 20 years of experience in supporting health initiatives across 30 countries.

Ben Rolfe: Good morning or afternoon, depending on where you are.

Dr. Rabindra Abeyasinghe: Hi, Great to join you today

Dr. Eva-Maria Christophel: It is an honour to be here on World Health Day to discuss vector-borne diseases with you and share experiences.

Karen Palmer: Let’s begin by looking at the state of vector-borne diseases in Asia and the Pacific.

Dr. Rabindra Abeyasinghe: Vector-borne diseases are reported from nearly all of the countries in Asia and the Pacific. Many of these are locally transmitted. Others are imported from affected countries in Asia and the Pacific or from outside. Malaria is possibly the most commonly occurring vector-borne disease in Asia Pacific countries. The Asia Pacific region also reports more than 75 percent of the global dengue burden. Lymphatic filariasis is endemic in over 25 countries of the Asia Pacific Region. Other vector-borne diseases are less common – such as schistosomiasis, leishmaniasis and Lyme disease.

Giovanni: Are vector-borne diseases a problem limited to the countryside, or do they affect city dwellers as well?

Dr. Rabindra Abeyasinghe: In response to Giovanni's question, vector-borne diseases affect everybody, diseases like dengue are mainly concentrated around urban centres, while malaria is predominantly rural.

Guest: May I ask, why is it that some of these diseases get so close to elimination, only to resurge? What happens to bring them back?

Ben Rolfe: The key is sustained commitment, and that means commitment from a number of players. It means commitment from the Ministry of Finance to make sure both prevention and treatment are prioritized. It means commitment from donors to fill financing gaps, and commitment from health service providers and communities to fight disease at the community level.

Dr. Eva-Maria Christophel: Economic development projects can contribute to the resurgence of malaria, such as hydroelectric power projects, unless they are adequately managed including health impact assessments and provision of health services to affected populations and migrant workers.

Dr. Rabindra Abeyasinghe: One of the lessons learnt during the malaria elimination in countries is the need for continued investment, until elimination is reached and certified. Consider the experience of Sri Lanka during the malaria eradication efforts of the late 1950s and early 60s, Sri Lanka nearly eliminated the disease. But a premature withdrawal of funding and change in approach resulted in a massive resurgence of malaria in 1967/8. This outbreak continued until an interruption of transmission in October 2012.

Ben Rolfe: If we take Vanuatu for example, a small country in the South Pacific; they have made huge gains in fighting malaria. Thousands of lives have been saved by the combined efforts of many people. The key is to make sure Donors, Governments and communities don't stop working when malaria cases reduce. You have to keep on the pressure.

Buzz Quito: WHO and others have been sounding the alarm about malaria parasites getting increasingly resistant to the most effective antimalarial drugs. How bad is the situation? What can be done to stop it from getting worse? And what is the back-up plan -- if parasites get resistant to the best current drugs, are there new drugs in the pipeline to act as a potential future safety net?

Dr. Eva-Maria Christophel: Antimalarial drug resistance is a great challenge for malaria control and elimination. For example: Thanks to good quality malaria drug resistance monitoring, the emergence of artemisinin resistance in the Greater Mekong Subregion was discovered early. Artemisinin being one of our most important antimalaria medicines, as one of the drugs in artemsinin-based combination therapy, operations were started quickly by national programmes, supported by the international community, to contain/eliminate resistant parasites. These efforts are ongoing and are an unprecedented response to malaria drug resistance. There are very few other malaria medicines in the pipeline.

Sian Powell: I would like to ask about the cost of control, bacteriological, vaccine, insecticide. Is it prohibitive for developing nations? Is there any rough way of gauging the cost, i.e. per capita annually? And what is the cost of these diseases to GDP etc?

Dr. Rabindra Abeyasinghe: In response to Sian's question, the vector-borne diseases have significant cost implications to developing countries, significantly retarding economic progress. The cost other the investment in elimination would be less in most countries, than the cost of having to control diseases over several decades. This, mind you, is just the economic impact, not to mention the human cost and possible loss of life.

Sophy: Hi, my question focuses on malaria. The eradication of malaria was a specific goal among the MDGs. One could argue that this has led to a narrow approach to tackling malaria. How can initiatives such as APLMA contribute to ensure that the eradication of malaria is going to be addressed in the larger context of sustainable development?

Ben Rolfe: Sophy, that's an excellent question. We are extremely fortunate that the global Public Health community are now coming together to address these threats under the banner of Universal Health Coverage. Initiatives like the Asia Pacific Leaders Malaria Alliance are able to contribute to this broader objective. Malaria is actually a great example because it affects some of the most poor and vulnerable people on the planet - building political support to meet the needs of neglected populations has lots of benefits in terms of a broader push for equitable access to health services.

Callum Thirkell NZ: Do you think we are likely to get close to eradication like we are with polio? And if we do are we likely to face the same issues with the final push, both in terms of the massive finances involved and the massive logistical and political push required?

Dr. Rabindra Abeyasinghe: Yes, the political commitment and financial resources required to ensure elimination of vector-borne diseases will undoubtedly be significant. However, the long term gains and associated socio economic development following the elimination of these diseases are significant. Several studies have illustrated a many fold return on investments made to eliminate vector-borne diseases.

Buzz Quito: Ben, you said that the key is to ensure that donors, governments and communities don't stop working when malaria cases reduce. However, despite the recent impressive gains against malaria, or perhaps because of them, there seems to be a complacency that we've got this thing licked. The Global Fund's malaria spends are declining too. How do we ensure that adequate resources are invested well into the future so the gains of the past and present are not squandered?

Ben Rolfe: Buzz, yes, thats a critical point. Certainly in Asia Pacific there are a lot of actors that have critical roles in maintaining the push,and the finance. The Asia Pacific Leaders Malaria Alliance is an excellent example of an initiative that came out of the region, and represents a regional response to the regional problem. The APLMA is working to help leaders, ministries of Health and Finance, and Regional Organizations think about and act on these issues. Long term sustainable financing is a key issue that leaders have asked us to investigate.

Wowie: Does the Philippines remain among the countries with the highest malaria cases? if it has reduced the number of cases, how did the country do it? If not, what still needs to be done?

Dr. Eva-Maria Christophel: The Philippines has in fact one of the lowest malaria morbidity rates in the Western Pacific Region. Tremendous progress has been achieved, and some provinces have been declared as malaria free by the national programme. How was this achieved? This includes political commitment, financial investments (both from the national budget as well as externally), effective interventions such as LLIN (long lasting insecticidal nets), artemisinin-based combination therapy and malaria diagnostic testing down to the barangay level, rolled out with a high coverage, and technical support.

Tan: With regards to the interventions provided by international organizations (e.g. Global Fund for medicines, nets, and insecticides), how does APLMA plan to engage in the region? I learned that this will be through innovative financing - but what will be the focus of resulting fund?

Ben Rolfe: Tan, you are absolutely right, the APLMA has been tasked with exploring innovative and sustainable financing solutions to what will be a long term issue. It's important to note that APLMA is not a fund; however, we will be helping Asia Pacific countries come together to identify new ways of working. Malaria, and particularly drug resistant malaria, is a truly regional issue - no one country can tackle it alone. What's exciting about this issue is that for the first time, we are seeing a real appetite for nations to cooperate at regional and sub-regional levels. Working out how this cooperation can be financed is a critical area for innovation. We are looking forward to supporting the debate.

Sian Powell: Do you expect a vaccine for dengue or malaria any time soon?

Dr. Rabindra Abeyasinghe: Sian, thanks for the question. Yes, vaccines are being developed for both dengue and malaria. The results of trials so far have been quite encouraging and it is hoped that the world would have effective vaccines for both diseases in the near future, hopefully within the next few years.

Guest: Ben, can you tell us a bit more about the task forces being set up by the APLMA?

Ben Rolfe: To help the region work through these issues, the APLMA will facilitate two Task Forces; the first on Access to Quality Medicines - a critical issue in ensuring the most vulnerable are reached and drug resistant malaria quashed. The second is on sustained financing. There is a lot of interest in creating the financing infrastructure to support the region to respond with its own financing.

Sophy: vector-borne diseases represent only one health issue. Do countries prioritise right if they allocate large amount of spendings to solve this problem instead of others, let's say maternal health?

Dr. Eva-Maria Christophel: It is not an either or. For one, in some countries some vector-borne diseases are a significant public health problem with suffering and possible disability, for example lymphatic filariasis or schistosomiasis. We have relatively easy and cost effective interventions available, such as preventive chemotherapy, where most of the medicines used are in fact donated by manufacturers to WHO. To many of these diseases, women and children and poor communities are especially vulnerable. Many on these interventions can be integrated into mother and child health programmes. On the other hand, diseases control programmes contribute a lot to strengthening health systems, such as surveillance, laboratory, and case management.

Guest: Moving to neglected diseases, what are the priorities? Which diseases need the most attention and what are the simple actions that can be taken to control, if not eliminate, these diseases?

Dr. Eva-Maria Christophel: One of the priority diseases in this region, affecting 22 countries, is lymphatic filariasis, a mosquito-borne parasite infection that causes disfiguring, disabling and stigmatizing disease that present as limb or scrotal swelling. An elimination programme in many endemic countries is underway with the main strategy being preventive chemotherapy, that is delivered by a combination of two free drugs annually, for at least five years. With good coverage rates, mass treatment can help eliminate this disease in 4 to 6 years. Our global goal is elimination of filariasis as a public health problem by 2020.

Sian Powell: How is climate change affecting the spread of disease-carrying mosquitos around the world?

Dr. Rabindra Abeyasinghe: Sian, Climate-change has a significant impect both on the distribution of mosquitoes and on the spread of vector-borne diseases. Climate change in many areas result in an increase of ambient temperature. Increases in temperature results in a more conducive environment for mosquitoes. It has now already been shown that increases in temperatures results in a geographical expansion of disease affected areas, including the reporting of diseases such as malaria from higher elevations. Additionally higher temperatures result in shorter development times for disease causing agents within mosquitoes and longer life spans for mosquitoes, thus resulting in more efficient transmission. This also makes control of these diseases more difficult.

Haiku: Is there a time of the year when vector-borne diseases are most prevalent?

Dr. Rabindra Abeyasinghe: Hi Haiku, vector-borne diseases are more prevelent during warmer periods of the year. Of course this depends on where you reside, but in most countries that have a cold season, disease transmission rates generally decline during the colder seasons. This is because the life spans of mosquitoes is affected by colder climates and pathogen development in vectors take longer. So disease transmission becomes less effective.

Wowie: thanks, ms. christophel. glad to know that the philippines is among those with lowest malaria morbidity rates. in terms of implementation of APLMA and WHO programs and projects, who is more difficult to deal with - the governments (national, provincial, local) or the people/communities? how do you overcome challenges? do you tap the media for information dissemination?

Dr. Eva-Maria Christophel: We have to work with all stakeholders to make the programmes work. The Philippines is a great example for political leadership and national investments in malaria, but also for good community mobilization. There are always ways to address and overcome challenges. Media play an important role to disseminate information, for health promotion and community mobilization. They are also very much used for the social marketing approach, as it is for example used in Cambodia to promote early malaria diagnosis and correct treatment of malaria in the private health sector.

Sian Powell: Which nation in Asia is the most significantly affected by dengue and malaria, say per head of population?

Dr. Rabindra Abeyasinghe: Sian, in the region, malaria is a big issue in the Pacific countries that currently have malaria transmission. On the other hand, we have several Mekong countries, as well as some Pacific countries, where dengue is endemic, meaning they literally have a high number of cases almost every year. On the other hand, we also have countries that experience explosive outbreaks of dengue in a given year and then don't have such outbreaks for 3 - 4 years, especially in Pacific Island countries.

Tan: Thanks for answering my question, Ben. To clarify, the Task Forces will act as the nations' advising bodies with regards to the relevant matter. How will the nations work after a sustainable financing model is agreed upon? Will APLMA continue its advisory role to the governments?

Ben Rolfe: Tan, it's an important point and very much up to the nations concerned. The APLMA will work with nations in the region, drawing on some of the best expertise the region has to offer, to present options. The nations and regional organizations will then be able to decide what options to adopt, pilot or dismiss. The key advantage of the APLMA is the ability to engage regional leaders in a debate that sometimes get lost in rather technical discussion.

Guest: How can people protect themselves and their families from these diseases?

Dr. Rabindra Abeyasinghe: Most of these vector-borne diseases are preventable, if exposure to the vector can be prevented or minimized. Self-protection is a key message for individuals – whether you are travelling to other countries or you are at home. Using insect repellents, for example, or bed nets treated with insecticides to protect yourself and your families from bites of vectors. Making sure there is no standing water in or around the home that contribute to vector breeding and reducing vector abundance results in reduced exposure to their bites.

Guest: What's the role of vaccines in vector-borne diseases?

Dr. Eva-Maria Christophel: Japanese encephalitis (JE) occurs in the islands of the Western Pacific in the east to the Pakistani border in the west, and from Korea in the north to Papua New Guinea in the south. JE distribution is very significantly linked to irrigated rice production combined with pig-rearing. There exists a vaccine for JE, and vaccination prevents this potentially serious disease. Currently vaccines are being tested for dengue and malaria, and preliminary results have been promising.

Tan: Which countries in the region would APLMA be working with in the next few years?

Ben Rolfe: Hi Tan, the APLMA aims to work as broadly as possible across the Asia Pacific region. The initiative was endorsed by the East Asia Summit, we have also been engaging with the Secretariat of the Pacific Community. We have had fantastic engagement in the first Task Force meeting, so I feel very positive about the impact of the initiative and the collaboration in these fairly early days.

Sian Powell: Thank you Dr Abeyasinghe. So, to clarify, last year, per head of population, which Asian nation had the most cases of dengue and which had the most of malaria, and which had the highest number of dengue fatalities and which the highest number of malaria fatalities?

Dr. Rabindra Abeyasinghe: Sian, the capacity of countries to report disease incidence is not equal. Hence it is difficult to provide accurate number of dengue or malaria cases per head of population.

Dr. Rabindra Abeyasinghe: Also the coverage across countries for reporting disease burden and indeed diagnosis is not uniform. So if we consider the number of reported cases, the highest number of malaria cases among countries in the region were reported from Papua New Guinea. As regards to dengue the highest number of cases reported was from Philippines. However we need to recognize that both these countries have relatively large populations.

Tan: Does APLMA welcome private sector engagement? such as sharing best practices, conducting case studies, and other collaborations? What are your ideas for the private sector at this stage?

Ben Rolfe: Tan, absolutely. The private sector has a huge role in so many ways. From investing in research and development, to manufacture and distribution of commodities, and providing treatment at community level. Some industries have also shown real leadership on this issue, for example Oil Search in PNG - very interesting work and a good example for the region.

Tan: Sounds really exciting, Ben!

Guest: What's the role of the private sector and industry in terms of contributing to elimination of some of these diseases?

Dr. Eva-Maria Christophel: There are priority vector-borne neglected diseases affecting the people in the poorest communities that are targeted for elimination. Lymphatic filariasis and schistosomiasis caused by parasitic worms and causing significant morbidity are targeted for elimination through mass drug administration using anthelminthics generously donated on a large scale to endemic countries by the manufacturers from the private sector. This drug donation to countries is coordinated by the WHO.

Guest: What are some of the success stories in Asia. Have any countries come close to eliminating any of these diseases? How did they do it?

Dr. Rabindra Abeyasinghe: There are many success stories with regards to the control of vector-borne diseases in Asia. Several countries have already eliminated malaria - Singapore and the Maldive Islands are examples. More recently Sri Lanka has interrupted malaria transmission with no locally transmitted cases reported since October 2012. The countries which achieved elimination were able to do this due to strong political commitment and adequate investment. Several other countries have eliminated Lymphatic Filariasis - the People's Republic of China, Solomon Islands and Republic of Korea among these.

Guest: Ben, how will we know if an initiative like the APLMA is having an impact?

Ben Rolfe: The political leadership in the region have acknowledged the urgent need to accelerate progress toward the 2015 World Health Assembly target of 75% reduction in malaria cases and deaths. Also, to address the critical issue of artemisinin resistant malaria. The APLMA is an important part of that effort. It will support the co-chairs, the Prime Ministers of Australia and Viet Nam, in bringing together some of the most knowledgeable and influential people in the region to identify solutions and see them through to fruition. I would hope and expect that we will see some new thinking, and more importantly renewed energy and commitment to tackle this really nasty disease.

Guest: Great, thanks so much.

Karen Palmer: I'd like to thank our experts for being with us today - I really enjoyed this discussion in celebration of World Health Day.

Ben Rolfe: Thanks, it was great to be asked to participate - some great questions. Please keep in touch via the APLMA website at aplma.org or find us on Twitter.

Dr. Eva-Maria Christophel: Last words...Diseases spread by vectors kill a million people every year and more than half of the world's population is at risk. Take simple measures to protect yourself, your family, and your community.

Dr. Rabindra Abeyasinghe: Thank you Karen and everybody who joined in this discussion. Let's continue our fight with the vector-borne diseases, let's protect ourselves and our families from the bites of vectors.

Karen Palmer: A transcript of this talk will be posted soon on ADB.org. Thanks again!

Ben Rolfe
Ben Rolfe is Executive Secretary ad interim at the APLMA, the secretariat of which is hosted by ADB. Formerly Pacific Lead Health Advisor at the Australian Department of Foreign Affairs and Trade, Mr. Rolfe has more than 20 years experience in supporting health initiatives across 30 countries.
Dr. Eva-Maria Christophel
Dr. Eva-Maria Christophel is Team Leader of Malaria and other Vectorborne and Parasitic Diseases at the WHO's Western Pacific Region, where she focuses on clinical and treatment aspects of malaria and other parasitic diseases. In 2003, Dr. Christophel became WHO Medical Officer for the Western Pacific Region. More recently, as Team Leader she has been focusing on the clinical and treatment aspects of malaria and other parasitic diseases.
Dr. Rabindra Abeyasinghe
Dr. Rabindra Abeyasinghe is Regional Entomologist at the World Health Organization's Regional Office for the Western Pacific based in Manila, Philippines. He has nearly 25 years of experience in malaria control including clinical management, parasitology, entomology, vector control and programme management.
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