Resistance to antimalarials is an ongoing threat to malaria elimination efforts with growing levels of P. falciparum artemisinin and Artemisinin-based Combination Therapies (ACTs) resistance reported in much of the Greater Mekong Subregion (GMS). To rapidly identify, monitor and respond to this threat, resistance surveillance is key. Recognizing its importance, the APMEN Surveillance and Response Working Group (SRWG) hosted the TechTalks webinar on resistance surveillance last September 30^th, 2021, 2 – 3.30 pm GMT+8.

The webinar was opened by Dr Rattanaxay Phetsavanh, Director General at the Department of Communicable Disease Control, Lao PDR and Chair of the SRWG, and moderated by Prof Richard J Maude, Head of the Epidemiology Department at the Mahidol-Oxford Tropical Medicine Research Unit (MORU) and Co-Chair of the SRWG.

“The public health crisis that began in 2019 stresses the importance of adapting to changes to prevent lapsing on the advances we have made. The presence of artemisinin-resistant Plasmodium falciparum in parts of this region continues to challenge elimination goals for many of our partners. And with recent findings from Uganda, whereby resistant strains were found to cause observable drops in the efficacy of artemisinin-combination therapies, it is important to note that this ongoing threat has now expanded beyond the GMS and into the most precarious malaria-endemic region in the world. More so than ever before, resistance surveillance is essential for countries to rapidly identify, monitor and respond to this threat.” Dr. Rattanaxay Phetsavanh

Prof Arjen Dondorp, Deputy Director of MORU and chair of the Regional Steering Committee for the Regional Artemisinin-resistance Initiative highlighted how rapid spread of resistance may emerge when ACT, used as first-line treatment for uncomplicated falciparum malaria, fails. He stressed the importance of identifying antimalarial drug resistance in isolation, that is, to artemisinin or specific partner drugs, rather than ACT as a whole when investigating ACT failure. He also introduced the complementary methods for surveying artemisinin resistance, including through clinical studies, in-vitro and ex-vivo sensitivity assays, and molecular markers.

Prof Olivo Miotto, Associate Professor from the Centre for Genomics and Global Health at the Wellcome Sanger Institute and MORU, shared the innovative way of genomic surveillance in the Greater Mekong Subregion through the GenRe-Mekong Project. The project integrates simple sample collection procedures to the role of frontline workers who collect thousands of dried blood spots from people with malaria, which are analysed to produce comprehensive report cards about parasite genotypes that are known to be associated with resistance to antimalarials. The project translates these genotypes into phenotype predictions and produces maps of antimalarial resistance rates that may be used by public health officials to make decisions regarding treatment choices, identify transmission hubs and assess the impact of targeted interventions, among other uses.

Dr Keo Chindavongsa, Deputy-Director of the Centre for Malaria, Parasitology and Entomology in Lao PDR, discussed how molecular marker results from the project were used to adopt treatment options in response to the expanding resistance marker in the south of Lao PDR, in addition to other antimalarial drug resistance surveillance methods currently used in the country such as ACT efficacy monitoring and therapeutic efficacy studies (TES).

Meanwhile, Dr Huynh Hong Quang, Vice Director and Head of the Tropical Diseases Clinical and Treatment Research Department of IMPE-QN Vietnam, described the various surveillance activities in Vietnam.  He shared that systematic molecular markers can be used as early warning signs to support antimalarial drugs monitoring. The usage of an early GenRe-Mekong genetic surveillance report confirming the presence of resistance parasite in areas bordering Cambodia to revise frontline therapies for three provinces after an in-vivo TES confirmed treatment failure. As stressed by Prof Olivo, genomic surveillance methods are still limited as the interpretation of results relies on known associations between markers and clinical efficacy. Both applications in Lao PDR and Vietnam echo this sentiment and highlight the complementary nature of genomic surveillance with other methods such as TES to conduct antimalarial drug resistance surveillance.

The webinar was attended by 195 participants across the world and is one of the SRWG’s activities aimed at maintaining and improving country programmes’ capacity to continue to effectively work towards their respective elimination goals. To view the full recording of the webinar please follow this link. Due to time limitations, questions unanswered during the webinar are also posted below.