Lead Institution: Walter and Eliza Hall Institute of Medical Research (WEHI)
Background
Overall, the Asia-Pacific region has achieved impressive reductions in malaria over the last 20 years. However, the Asia-Pacific ICEMR, with funding from2017-2024, documented strongly diverging regional malaria trends: Cambodia is nearing Plasmodium falciparum elimination but is confronted with the challenge of resilient residual P. vivax transmission, while Papua New Guinea (PNG) recorded 1.2 million new cases in 2021.
Despite their differing progress, both countries face common challenges: optimal allocation of sparse resources in heterogeneous transmission settings driven by asymptomatic infections, environmental change affecting malaria transmission, emerging drug and insecticide resistance and the specific challenge of eliminating P. vivax.
The renewed Asia-Pacific ICEMR will address these challenges by conducting a coordinated set of field, laboratory and modelling studies across five sites, including one site in a very low transmission area (Mondulkiri Province) in Cambodia and four sites in low (Autonomous Region of Bougainville), moderate (East New Britain Province) or high transmission (Madang Province and East Sepik Province) areas in PNG. Researchers will:
- Develop and validate optimized surveillance and response systems that combine traditional epidemiological and vector surveillance with targeted reactive population surveys;
- Understand key drivers of ongoing P. vivax transmission in a wide range of transmission intensity settings and identify locally optimal combinations of interventions to restrict and eventually interrupt transmission;
- Generate evidence on the ability of novel tools and interventions to improve access to P. vivax radical cure and target the asymptomatic P. vivax reservoir; and
- Determine the threat of emerging drug and insecticide resistance.
Research Areas
In the Epidemiology Project, health facility surveillance, cross-sectional, and reactive case detection studies augmented by novel molecular, genomic, and serological diagnostic assays will be used to accurately measure malaria transmission and identify key drivers of residual transmission. Through in-depth molecular surveillance and efficacy monitoring researchers will map the spread Pf artemisinin resistance (ArtR) in PNG and confirm the emergence of Pv ArtR and mefloquine resistance in Cambodia, while conducting coordinated studies to address barriers to increased access and efficacy of Pv radical cure.
The Transmission Project will conduct in-depth vector surveillance coupled with vector genetic studies to better understand the epidemiological observations in Project 1, map the recent emergence of pyrethroid resistance in PNG, document vector range expansions, assess the decreasing effectiveness of vector control tools, investigate factors facilitating asymptomatic Pv transmission and evaluate novel transmission-blocking interventions. Throughout the research program, policy-relevant scenario modelling will be used determine locally optimal combinations of interventions. Together, these studies will provide malaria programs with accurate and timely data for action and new solutions to accelerate malaria elimination.
These interconnected, multi-disciplinary studies aim to identify and characterize critical parasite, vector, and host features that contribute to continued transmission despite intensive national malaria control and elimination programs. A detailed understanding, not only of where people with malaria infections and disease are living, but also where they may have acquired infections and where they could spread them, is crucial to eliminating malaria from the Asia-Pacific region.
Regional Impact
The Asia-Pacific ICEMR maintains very close contacts with the National Malaria Control Programs in PNG and Cambodia and aims to provide insights that support evidence-based policy making and program implementation. Any knowledge gained is leveraged regionally through its close links with the Asia-Pacific Malaria Elimination Network (APMEN, including its Vivax, Surveillance and Vector Control working groups), as well as the NHMRC Australian Centre of Research Excellence in Malaria Elimination (ACREME).
Past Achievements
Over the past 15 years the Asia-Pacific ICEMR has amassed a comprehensive epidemiological and entomological data set monitoring changes in the burden of malaria and identifying and characterizing critical parasite, vector, and host features that contribute to continued transmission despite intensive national malaria control and elimination programs in the Western Pacific Region.
Key findings from this past research include:
- Living in close contact with the forest or a forest occupation are the main risk factors for P. vivax infection in Cambodia, with daytime biting being an important aspect of mosquito species’ behavior. Asymptomatic carriage of P. vivax is the most common presentation for malaria infection in this group, highlighting the necessity of developing new diagnostic tools to identify this population followed by a treatment program including radical cure to reduce the risk of transmission.
- ICEMR data identifying early outdoor biting preferences in vector species in PNG has facilitated the evaluation of additional vector control tools to redress a reliance on long-lasting insecticidal nets (LLINs) as the main intervention.
- Additionally, by working in close collaboration with the National Malaria Control Program (NMCP), reduced bioefficacy of LLINs was observed, with only 16 percent of LLINs manufactured after 2013 fulfilling the required WHO bioefficacy standards. In contrast, all LLINs manufactured prior to 2013 met the WHO bioefficacy standards. These results suggest that decreased bioefficacy of LLINs may be contributing to the malaria resurgence in PNG and increased scrutiny of LLIN quality is warranted.
- Surveillance of P. falciparum haplotypes for artemisinin resistance associated mutation C580Y revealed mixing between Wewak and West Papuan isolates, suggesting these mutants may have originated elsewhere on the island of New Guinea. ICEMR findings prompted the establishment of a national molecular sentinel surveillance program for the detection of P. falciparum markers of Artemisinin resistance.
- Working with communities and health service providers to maximize acceptability of new interventions has emerged as a key component of successful implementation strategies.
Study Sites
View Associated sites for the Southwest Asia ICEMR in a larger map
Collaborating Institutions
- Papua New Guinea Institute of Medical Research, Port Moresby, PNG
- Institut Pasteur Cambodia, Phnom Penh, Cambodia
- Burnet Insititute, Melbourne, Australia
- James Cook University, Cairns, Australia
Staff
Project Leads
- Leanne Robinson, Burnet Institute, Melbourne, Australia - Epidemiology
- Maria Ome-Kaius, PNG Institute of Medical Research, PNG – Epidemiology PNG Lead
- Jean Popovici, Institut Pasteur Cambodia, Cambodia – Epidemiology Cambodia Lead
- Stephan Karl, PNG Institute of Medical Research, PNG, and AITHM James Cook University, Australia - Transmission