Rapid Fire Presentation 8th International Conference on Plasmodium vivax Research 2022

Post-treatment hemozoin levels in malaria patients in Papua New Guinea quantified using rotating-crystal magneto-optical detection (#333)

Agnes Orban 1 , Andrea P Molnar 1 , Sze-Ann Woon 2 , Clemencia Ibam 3 , Lincoln Timinao 3 4 , Adam Butykai 1 , Lina Lorry 3 , Maria Pukancsik 1 , Beata G Vertessy 1 , Erika Orosz 5 , Istvan Kucsera 5 , Timothy ME Davis 6 , Moses Laman 3 , Brioni R Moore 2 , Istvan Kezsmarki 1 7 , Stephan Karl 3 4
  1. Department of Physics, , Budapest University of Technology and Economics, Budapest, Hungary
  2. Curtin Medical School , Curtin University, Bentley, WA, Australia
  3. Vector-borne Diseases Unit, Papua New Guinea Institute of Medical Research, Madang, Madang Province, Papua New Guinea
  4. James Cook University, Smithfield, QLD, Australia
  5. National Public Health Center, Budapest, Hungary
  6. School of Medicine and Pharmacology, The University of Western Australia, Perth, WA, Australia
  7. Institute of Physics, University of Augsburg, Augsburg, Germany

Background: Hemozoin is a biomarker that accumulates in the human body during malaria infection. Due to its unique physical properties, magneto-optical methods have been developed that are able to quantify very small concentrations of hemozoin, in principle sensitive enough to enable rapid diagnosis of infections. Persistence of hemozoin after treatment may compromise its specificity as a marker for diagnosis of acute infections. In the present study we quantified hemozoin levels in a small population of patients treated for malaria, using rotating-crystal magneto-optical detection (RMOD).

Methods: A total of 139 patients with confirmed Plasmodium spp. infections were treated with artemisinin combination therapy and primaquine. Alongside clinical evaluations, their hemozoin levels were measured up to four weeks following treatment using an established RMOD protocol.

Results: Hemozoin levels observed after treatment followed species-specific trends. For P. vivax we typically observed a rapid reduction in hemozoin up to day 3. However, hemozoin levels in several individuals stabilised, or even increased towards the end of the follow-up period. In P. falciparum infections, the presence of gametocytes delayed hemozoin clearance. Overall, magneto-optical signals remained elevated as compared to malaria naïve individuals during the follow-up period.

Conclusions: Elevated hemozoin levels in peripheral blood may not be reflective of acute malaria infections. While most of our observations are well explained by the underlying species-specific parasite clearance processes following antimalarial treatment, some of our results are intriguing, and may hint towards hemozoin being a marker for hidden P. vivax infections or the early onset of relapses.