Background:
Malaria is a serious disease caused by parasites spread by mosquitoes. To better diagnose and treat malaria, researchers need to learn more about where the parasites go when they enter a person's body. They want to see if they can locate the malaria parasites in the body using imaging scans.
Objective:
To learn whether imaging scans can locate parasites in people with malaria.
Eligibility:
Healthy people aged 18 to 54 years. They must be enrolled in protocol IRB001970 or IRB002627 for controlled malaria infection.
Design:
Participants will be screened. They will have blood drawn and a physical exam, including an abdominal exam to check the size of their spleen.
Participants for this study will have 2 or 3 positron emission tomography/computed tomography (PET/CT) scans: The first will be about 3 days before they are deliberately infected with malaria for a different study. The second will be about 13 days later, while they have the disease. The third scan is optional; it will be done about 3 and 1/2 weeks after the second scan.
For each scan, participants will receive a radioactive tracer called fluorodeoxyglucose (FDG). FDG will be injected through a tube inserted into a vein. They will lie on a table that slides through a doughnut-shaped machine. PET/CT uses x-rays to create images of the inside of the body.
All participants will have a follow-up visit about 3 and 1/2 weeks after the second scan. The blood draw and physical exam will be repeated. This visit may be combined with the third scan for those who choose it.
Aged >=18 and <=54 years.
Able to provide informed consent.
Co-enrolled in NIH protocol IRB001970, "Phase 1 study of induced blood-stage malaria in healthy malaria-naive adults to assess the safety and infectivity of Plasmodium vivax challenge agent and evaluate transmission in mosquito feeding assays" or IRB002627, "Phase 1/2 study of transmission-blocking vaccine Pvs230D1-EPA/Matrix-M in healthy malaria-naive adults using a Plasmodium vivax controlled human malaria infection model."
Willing to allow long-term storage of study samples for future research.
Pregnancy or lactation.
History of splenectomy.
History of diabetes or poorly controlled blood sugar, in the judgement of the investigators, would prevent completion of FDG-PET/CT scan.
Currently undergoing therapy with drugs that, in the judgment of the investigators, may interfere with biodistribution of FDG (e.g., insulin that cannot be held or metformin that cannot be stopped for 48 hours prior to each FDG-PET/CT.).
Single group
18F-fluorodeoxyglucose-positron emission tomography/computed tomography scan
Diagnostic testParticipants are co-enrolled in a Plasmodium vivax challenge model protocol at the NIH Clinical Center. These participants will undergo up to 3 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET)/computed tomography (CT) scans of their chest, abdomen, and pelvis. PET/CT scans will occur at baseline (before controlled human malaria infection (CHMI) inoculation), and at the expected time of peak parasitemia. Participants may have an optional 3rd PET/CT scan at day 34 after the CHMI inoculation. FDG uptake will be used to visualize organ-specific changes as a result of malaria infection.
To measure changes in spleen standardized uptake value (SUV) from baseline in participants undergoing P. vivax CHMI using PET/CT imaging
Percentage change in mean spleen SUV from baseline to post-CHMI
To measure changes in organ specific uptake of FDG from baseline in participants undergoing P. vivax CHMI using PET/CT imaging
Percentage change in max spleen SUV Percentage change in peak spleen SUVPercentage change in spleen volume Percentage change in liver volumePercentage change in liver SUVPercentage change in bone marrow SUV
Explore the relationship between dyserythropoiesis, hematological abnormalities, and bone marrow/splenic involvement in acute P. vivax malaria.
CBC with differential, reticulocyte count, and erythropoietin (EPO) at baseline, at the time of the second FDG-PET/CT, and at the end of the CHMI-related activities performed under the co-enrolled study.
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