Photo credit: Woodford J., Gillman A., Jenvey P., Roberts J., Woolley S., Barber BE, et al. (2021) Positron emission tomography and magnetic resonance tomography in experimental malaria in humans to identify organ-specific changes …
The malaria parasite Plasmodium vivax can accumulate in the spleen to a greater extent shortly after infection than its well-known relative P. falciparum. This is evident from new research published by John Woodford of the University of Queensland, Brisbane, Australia and colleagues in the Open Access Diary PLOS medicine.
The treatment and management of P. vivax and P. falciparum infections requires study of their various routes of infection, and our limited understanding of the disease pathology has generally relied on indirect and imprecise approaches. Woodford and colleagues studied 7 healthy participants who were infected with either P. vivax or P. falciparum under controlled conditions. They were subjected to positron emission tomography (PET) and magnetic resonance imaging (MRI) 7 days before infection and again 7 to 11 days after treatment with malaria.
The team examined the participants’ spleen, liver and bone marrow for changes in shape or structure, as well as glucose metabolism, which would indicate an accumulation of the parasite in individual organs. In the spleen, glucose metabolism increased after infection, which was more pronounced in participants infected with P. vivax. Neither the liver nor the bone marrow were affected at this early stage of the infection. Despite the small size of the study, research shows that imaging in this way can help understand the accumulation of malaria parasites in specific organs and change previous thinking about P. vivax behavior in the “blood stage” of infection.
Dr. Woodford notes, “Out of the cycle malaria parasites contribute to the disease but are very difficult to study. By conducting this novel imaging study on participants undergoing experimental malaria infection, we were able to examine what happens in certain organs in the earliest stages of infection, the blood stage. This is further evidence that parasites of the important species Plasmodium vivax have a particular predilection for the spleen, and shows how controlled infection studies can accommodate unique exploration targets that cannot otherwise be studied in humans. “
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Funding: This project was supported by an HIRF Seed Funding Grant, Metro North Hospital and Health Service (JW), and the Australian National Health and Medical Research Council (JSM # 1135955, # 1037304, # 1132975, and NMA # 1135820 , 1098334). . Clinical trial participants were funded by the Australian National Health and Medical Research Council (JSM # 1132975), the Bill and Melinda Gates Foundation (JSM OPP1111147), and the Global Health Innovative Technology Fund. Funders had no role in the design of the study, data collection and analysis, the decision to publish, or the preparation of the manuscript.
Competing interests: The authors have stated that there are no competing interests.
Citation: Woodford J., Gillman A., Jenvey P., Roberts J., Woolley S., Barber BE, et al. (2021) Positron Emission Tomography and Magnetic Resonance Imaging in Experimental Malaria in Humans to Identify Organ-Specific Changes in Morphology and Glucose Metabolism: A Prospective Cohort Study. PLoS Med 18 (5): e1003567. https: /