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Haematological response in experimental human Plasmodium falciparum and Plasmodium vivax malaria.
Woolley, Stephen D; Marquart, Louise; Woodford, John; Chalon, Stephan; Moehrle, Joerg J; McCarthy, James S; Barber, Bridget E.
  • Woolley SD; QIMR Berghofer Medical Research Institute, 300 Herston Road, Brisbane, QLD, 4006, Australia.
  • Marquart L; Centre of Defence Pathology, Royal Centre for Defence Medicine, Joint Hospital Group, ICT Building, Birmingham Research Park, Vincent Drive, Birmingham, UK.
  • Woodford J; Clinical Sciences Department, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK.
  • Chalon S; QIMR Berghofer Medical Research Institute, 300 Herston Road, Brisbane, QLD, 4006, Australia.
  • Moehrle JJ; QIMR Berghofer Medical Research Institute, 300 Herston Road, Brisbane, QLD, 4006, Australia.
  • McCarthy JS; Laboratory of Malaria Immunology and Vaccinology, NIAID, National Institutes of Health, Bethesda, USA.
  • Barber BE; Medicines for Malaria Venture, 20 Route de Pre-Bois, PO Box 1826, 1215, Geneva, Switzerland.
Malar J ; 20(1): 470, 2021 Dec 20.
Article in English | MEDLINE | ID: covidwho-1639119
ABSTRACT

BACKGROUND:

Malaria-associated anaemia, arising from symptomatic, asymptomatic and submicroscopic infections, is a significant cause of morbidity worldwide. Induced blood stage malaria volunteer infection studies (IBSM-VIS) provide a unique opportunity to evaluate the haematological response to early Plasmodium falciparum and Plasmodium vivax infection.

METHODS:

This study was an analysis of the haemoglobin, red cell counts, and parasitaemia data from 315 participants enrolled in IBSM-VIS between 2012 and 2019, including 269 participants inoculated with the 3D7 strain of P. falciparum (Pf3D7), 15 with an artemisinin-resistant P. falciparum strain (PfK13) and 46 with P. vivax. Factors associated with the fractional fall in haemoglobin (Hb-FF) were evaluated, and the malaria-attributable erythrocyte loss after accounting for phlebotomy-related losses was estimated. The relative contribution of parasitized erythrocytes to the malaria-attributable erythrocyte loss was also estimated.

RESULTS:

The median peak parasitaemia prior to treatment was 10,277 parasites/ml (IQR 3566-27,815), 71,427 parasites/ml [IQR 33,236-180,213], and 34,840 parasites/ml (IQR 13,302-77,064) in participants inoculated with Pf3D7, PfK13, and P. vivax, respectively. The median Hb-FF was 10.3% (IQR 7.8-13.3), 14.8% (IQR 11.8-15.9) and 11.7% (IQR 8.9-14.5) in those inoculated with Pf3D7, PfK13 and P. vivax, respectively, with the haemoglobin nadir occurring a median 12 (IQR 5-21), 15 (IQR 7-22), and 8 (IQR 7-15) days following inoculation. In participants inoculated with P. falciparum, recrudescence was associated with a greater Hb-FF, while in those with P. vivax, the Hb-FF was associated with a higher pre-treatment parasitaemia and later day of anti-malarial treatment. After accounting for phlebotomy-related blood losses, the estimated Hb-FF was 4.1% (IQR 3.1-5.3), 7.2% (IQR 5.8-7.8), and 4.9% (IQR 3.7-6.1) in participants inoculated with Pf3D7, PfK13, and P. vivax, respectively. Parasitized erythrocytes were estimated to account for 0.015% (IQR 0.006-0.06), 0.128% (IQR 0.068-0.616) and 0.022% (IQR 0.008-0.082) of the malaria-attributable erythrocyte loss in participants inoculated with Pf3D7, PfK13, and P. vivax, respectively.

CONCLUSION:

Early experimental P. falciparum and P. vivax infection resulted in a small but significant fall in haemoglobin despite parasitaemia only just at the level of microscopic detection. Loss of parasitized erythrocytes accounted for < 0.2% of the total malaria-attributable haemoglobin loss.
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Full text: Available Collection: International databases Database: MEDLINE Main subject: Malaria, Vivax / Malaria, Falciparum / Parasitemia / Erythrocytes / Anemia / Antimalarials Type of study: Experimental Studies Topics: Long Covid Limits: Adult / Female / Humans / Male / Middle aged / Young adult Language: English Journal: Malar J Journal subject: Tropical Medicine Year: 2021 Document Type: Article Affiliation country: S12936-021-04003-7

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Full text: Available Collection: International databases Database: MEDLINE Main subject: Malaria, Vivax / Malaria, Falciparum / Parasitemia / Erythrocytes / Anemia / Antimalarials Type of study: Experimental Studies Topics: Long Covid Limits: Adult / Female / Humans / Male / Middle aged / Young adult Language: English Journal: Malar J Journal subject: Tropical Medicine Year: 2021 Document Type: Article Affiliation country: S12936-021-04003-7