Examination of mosquitos for supporting a change of thinking and practice to eliminate vector diseases
Expert view: Why We Need to Focus on Integrated Efforts for Malaria Elimination in Asia Pacific

From Parasites to People: Bridging the Transmission Gap

WHO and regional National Malaria Control Programmes (NMCPs) in Asia Pacific have set a target to eliminate malaria by 2030. But without a more targeted shift in thought and practice, many programs are unlikely to reach elimination targets, argues Latifeh Dahmash, Technical Specialist for Vector Diseases at the international non-profit Malaria Consortium in Bangkok, Thailand.

Standing among peers in the busy foyer of a conference hall in Bangkok, Thailand, experts gather to reflect on the successes, current progress, and remaining challenges for malaria control measures across the region. 

This tropical disease is endemic to many of the countries here, and although some have managed to achieve elimination status, malaria continues to be a leading cause of death and disability for many others: The World Health Organization (WHO) reported 14 million cases across the region in 2017 alone (around five percent of cases globally), although recent evidence strongly suggests this number to be grossly underestimated. The region thus continues to carry the second highest burden of the disease outside of the African continent. However, whilst malaria transmission within many of the endemic countries across the African continent is largely holo-endemic – spread throughout the country, placing the majority of the population at risk – for Asia Pacific, transmission is primarily hypo- or meso-endemic: concentrated in smaller, defined locations, where is it assumed that surveillance and control interventions can be more easily targeted and implemented. Subsequently, WHO and regional National Malaria Control Programmes (NMCPs) have ambitiously set a target to achieve elimination of the disease by 2030.

Latifeh Dahmash
Credit: Latifeh Dahmash, Bayer AG

 

 

 

Latifeh Dahmash, Technical Specialist, Vector Diseases, at the Malaria Consortium in Bangkok, Thailand.

Remaining Challenges are Diverse, and often Unseen

The region has made, and continues to make, considerable progress to bring down the number of new malaria infections. This has largely been a result of increased investment in targeted case detection methods, expansion in the deployment of essential diagnostic tools and treatment packages, and improved access to essential health services for more isolated population groups, often most at risk of the disease. Nevertheless, overcoming the remaining challenges will be no easy feat. Southeast Asia remains the epicenter of drug-resistant malaria strains, stalling progress particularly within the Greater Mekong sub-region. The predominant disease parasite circulating within many Asia Pacific countries, plasmodium vivax, is difficult to detect with current diagnostic tools, and can survive undetected in hosts for many years after they have been infected. This means that people can both carry and transmit the disease even if they show no signs of symptoms of its presence. Moreover, controlling transmission in border and forested regions – the high risk ‘hot spot’ areas for malaria transmission- remains problematic as health systems struggle to capably track and reach the many mobile and migrant populations living and crossing these areas with necessary prevention and treatment services. 

One crucial component of malaria control that has often been difficult to apply in practice is that related to the infected mosquitoes responsible for carrying and spreading the disease. These mosquitoes vary in their biology, characteristics, and behavioral traits, and this variation can affect how and where they are able to spread the disease, as well as how they respond to the various vector control measures deployed. For the Asia Pacific region, there are concerns that insecticide treated bednets, a core preventive intervention, are having limited effectiveness in many areas: we are seeing increasing evidence for malaria mosquitoes preference for biting outdoors and during daytime hours when people are not protected by bednets, and where alternative interventions are inappropriate and/or unavailable.

Entomologist conducts surveillance activities for Anopheles mosquitos
Credit: Latifeh Dahmash, Bayer AG

 

 

A Vietnamese entomologist conducts surveillance activities for Anopheles mosquitoes – those with the potential to spread malaria.

 

Building Partnerships, Developing Strategies and Finding Solutions

Recognition of these constraints has prompted a recent call from technical and program specialists alike for a renewed focus on the need for appropriate, practical and sustainable approaches to entomological surveillance and response across the Asia Pacific. To date, few countries across the region have developed and deployed guidelines to employ this in practice. Without paying closer attention to the shifting role of the vector in the transmission cycle, we are missing a critical opportunity to better focus our strategy, investments, and tools to collectively and vigorously drive the disease closer to elimination. 

So, how can we realistically and purposefully bridge the gap between people and parasite transmission in order to strengthen the response to malaria and other vector-borne disease threats? First and foremost, generating evidence for strengthening vector control or entomology activities within current control and surveillance efforts needs to be firmly articulated, encouraged, and guided by national programs. Partnering with research and civil society organizations to conduct both lab-based and operational research can enable National Malaria Control Programme personnel in the Asia Pacific region to better understand why, where, and how vector control initiatives may be failing and identify what alternative strategies are needed instead. Given the rising cases of other mosquito-borne diseases for many countries across the region – notably dengue fever, as well as the steady geographical expansion of chikungunya virus – supporting and advocating for a stable and competent vector control workforce is a necessity for disease elimination.

Next, investing in people and empowering them with knowledge and skills is crucial for meaningful program decision making. There is need to strengthen basic technical skills and tools for mosquito sampling, as well as for identification and presence of insecticide resistance. Continuous capacity building and skills training activities are rarely provided for these practices: as the number of reported malaria cases start to decline, financial and human resources are often prioritised for other health and disease threats regardless of the on-going risk of malaria transmission in these areas. Continued, tailored, appropriate practical skills training for vector control staff is essential to sustain and accelerate progress in driving down transmission, especially in locally-affected areas. Existing and novel methods for enhanced knowledge sharing – face-to-face technical workshops and training, as well as online practice and resource exchange communities – should be sourced, supported, and encouraged to facilitate integrated and complementary learning for staff across the region.

And lastly, identifying collaborative mechanisms to better support vector control personnel is an ever discussed, yet rarely practiced approach to disease prevention and control. The mosquito alone is not responsible for transmission and parasites/viruses know no borders: people, environments, and ecologies in tandem with the vector determine the scale and intensity of disease spread. Numerous ‘how to’ guidelines and recommendations circulate in Asia Pacific and beyond, outlining the need for and benefit of collaborative partnerships for better vector-borne disease prevention control. Few make it past the four walls of the offices they’re housed in. Identifying opportunities to bring together those targeting the people at risk with those targeting the vector not only brings a chance for more comprehensive prevention techniques, but also cost-effective, practical, and sustainable approaches through skills and knowledge transfer. The few examples we have of such multi-sectoral approaches to disease control emphasize one thing: when done with focus and intent, they work, and work well.

The motto of World Malaria Day 2019 – ‘zero malaria starts with me’ – emphasizes the unique role that each individual, in any setting, can play in the fight against malaria. I would argue instead that reaching zero malaria starts instead with us: Elimination starts with prevention, prevention starts with focus and focus starts with people. Strategic collaboration, co-focal surveillance and case investigations, and cohesive, complementary response strategies will need to be the sharp focus across Asia Pacific if we are to get the necessary tools to the places they have yet to reach. Doing this will also take honesty and courage from all partners in this field: honesty about the nature, scope, and nuances of the persistent challenges and gaps in practice, and courage to be willing and prepared to adapt thinking and practice to more definitively meet these. Spirited advocacy has fostered the intent for malaria elimination, but focused and coordinated management of the vectors, both human and mosquito, will be the mechanism by which we will drive it closer to elimination.

Latifeh Damash conducts entomological surveillance together with a WHO representative
Credit: Latifeh Dahmash, Bayer AG

 

During a research trip in Cambodia, Latifeh Damash conducts entomological surveillance together with a WHO representative.

 

Latifeh Dahmash
Technical Specialist, Vector Diseases, at the Malaria Consortium in Bangkok, Thailand