Oral Presentation 8th International Conference on Plasmodium vivax Research 2022

Field evaluation of LAMP for detection of Plasmodium vivax infections in pregnancy in Papua New Guinea (80382)

Benishar Kombut 1 2 , Shazia Ruybal-Pesántez 3 4 , Pele Melepia 2 , Ruth Fidelis 2 , Kael Schoffer 3 , Elma Nate 1 , Lina Lorry 1 , Rachael Farquhar 4 , Maria Ome Kaius 1 3 , Livingstone Tavul 1 , Michelle JL Scoullar 4 5 , Philipe Boeuf 4 , Michaela Riddell 6 7 , Lisa Vallely 6 7 , Andrew Vallely 6 7 , Chris Morgan 4 , Freya Fowkes 4 , James G Beeson 4 , Jack Richards 4 , Fiona Angrisano 4 , William Pomat 7 , Ewurama Owusu 8 , Sandra Incardona 8 , Xavier Ding 8 , Sternard Hiasihri 2 , Moses Laman 1 , Leanne Robinson 1 4
  1. PNG Institute of Medical Research, Madang, Papua New Guinea
  2. Burnet Institute for Medical Research, Kokopo, Papua New Guinea
  3. Walter and Eliza Hall Institute, Melbourne, Victoria, Papua New Guinea
  4. Macfarlane Burnet Institute for Medical Research, Melbourne, Victoria, Australia
  5. University of Melbourne, Melbourne, Victoria, Papua New Guinea
  6. Kirby Institute, Sydney, New South Wales, Australia
  7. PNG Institute of Medical Research, Goroka, Papua New Guinea
  8. FIND, Geneva, Switzerland

Plasmodium vivax infections during pregnancy contribute to adverse outcomes, such as maternal and neonatal anaemia, as well as low birth weight. These infections are often submicroscopic and asymptomatic. However, diagnostic tools for P. vivax infections in non-reference laboratory settings are limited to light microscopy (LM) and rapid diagnostic tests (RDTs), even though studies using sensitive polymerase-chain reaction (PCR) techniques indicate that at least half of all infections in maternal venous blood are missed by LM or RDTs. As such, the development and validation of new sensitive tools for P. vivax detection remains a high priority.

This study assessed the performance of P. vivax loop-mediated isothermal amplification (LAMP) for the detection of malaria during pregnancy in Papua New Guinea (PNG).  986 pregnant women attending ante-natal care clinics in East New Britain Province were enrolled between August 2018-May 2019.  Standard Carestart™ Malaria HRP2/pLDH (Pf/Pan) Combo tests, Pan/Pv loop-mediated isothermal amplification (LAMP), quantitative real-time PCR (qPCR) and ultra-sensitive qPCR (usqPCR) were performed and the performance of LAMP was evaluated, using qPCR and usqPCR as reference standards for all comparisons.

The prevalence of mixed and/or non-Pf Plasmodium spp. infections by RDT was 0.2%, whilst the prevalence of P. vivax infections by qPCR and usqPCR was 7% and 22%, respectively. Compared to qPCR, LAMP detected a much higher prevalence of P. vivax (12%) infections with a sensitivity and specificity of 83% and 93% respectively. Using the usqPCR as the reference, the sensitivity of LAMP decreased to 47%, but specificity remained high (98%). This study provides evidence that there is a high burden of P. vivax malaria infections that remain undetected and untreated in the first and second trimester of pregnancy and that LAMP is a promising field deployable tool for detecting harmful sub-clinical P. vivax malaria during pregnancy in PNG.