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Conference Agenda

Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).

Daily Overview

Session

CP17.1: Epidemiology & Diagnostics 10 min talks
Location: Lecture Theatre 3
Session Chair: Deepani Fernando, QIMR Berghofer
Session Chair: Luke Hall, St Vincent's Hospital Sydney

Presentation 3

Population genetics of P. falciparum clinical and asymptomatic infections at low transmission

Sonakshi Madan^1,2, Kirsty McCann^1,2, Zahra Razook^1,2, Dulcie Lautu-Gumal^1,2,3,4,8, Shazia Ruybal-Pesántez^3,4,5, Jessy Vibin¹, Katelyn Stanhope^1,2, Johanna H. Kattenberg⁶, Anaïs Pepey⁷, Nimol Khim⁷, Livingstone Tavul⁸, Maria Ome-Kaius⁸, Manuel Hetzel^9,10, Amélie Vantaux⁷, Benoit Witkowski⁷, James W. Kazura¹¹, Moses Laman⁸, Ivo Mueller^3,4, Leanne J. Robinson^2,3,8, Alyssa E. Barry^1,2,3

1: Centre for Innovation in Infectious Disease and Immunology Research (CIIDIR), Deakin Institute for Mental and Physical Health and Clinical Translation (IMPACT), and School of Medicine, Deakin University, Geelong, Victoria, AUSTRALIA; 2: Life Sciences Discipline, Burnet Institute, Melbourne, Victoria, AUSTRALIA; 3: Population Health and Immunity Division, Walter and Eliza Hall Institute, Parkville, Victoria, AUSTRALIA; 4: Department of Medical Biology, University of Melbourne, Parkville, Victoria, AUSTRALIA; 5: MRC Centre for Global Infectious Disease Analysis, Imperial College London, UNITED KINGDOM; 6: Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, BELGIUM; 7: Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, CAMBODIA; 8: Vector Borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, PAPUA NEW GUINEA; 9: Swiss Tropical and Public Health Institute, Allschwil, SWITZERLAND; 10: University of Basel, Basel, SWITZERLAND; 11: Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, USA

Countries close to malaria elimination are reporting significant resurgence following periods of declining prevalence. Reduced transmission decreases opportunities for genetic recombination and generates geographically isolated hotspots of infection, resulting in lower diversity and increased population structure. With reduced exposure, naturally acquired immunity wanes, potentially rendering human populations more susceptible to outbreaks. But paradoxically, many low-transmission countries also record high prevalence of asymptomatic infections. We hypothesised that these asymptomatic cases are associated with immunologically familiar, locally circulating strains whereas clinically infectious parasites are potentially imported. We analysed Plasmodium falciparum samples from a period of low transmission (2012) prior to resurgence (2016) in East Sepik, Papua New Guinea (PNG), and from a low-transmission setting with ongoing occupational exposure in Mondulkiri, Cambodia, by sequencing a validated genome-wide single nucleotide polymorphism (SNP) barcode and immune evasion antigen marker (varcode). Parasite lineages underlying clinical infections in PNG were clonal and distinct from circulating asymptomatic isolates, suggesting potential importation and outbreak caused by immunologically unfamiliar parasites. Infections in Cambodia however indicate a more complex dynamic between parasite strain and host factors. These results emphasise how surveillance reliant on just clinical infections inadequately reflects control success and must account for asymptomatic malaria for sustainable reduction and elimination.