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A longitudinal cohort study of Plasmodium vivax relapses in Central Africa

Award Number: R21AI190606
ORGANIZATION: NATIONAL INSTITUTE OF ALLERGY & INFECTIOUS DISEASES
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)
PERIOD OF PERFORMANCE START DATE: 08/25/2025
PERIOD OF PERFORMANCE END DATE: 07/31/2027

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A longitudinal cohort study of Plasmodium vivax relapses in Central Africa - PROJECT SUMMARY Title: A longitudinal cohort study of Plasmodium vivax relapses in Central Africa Plasmodium vivax (Pv) infections caused by relapse are an important cause of morbidity and source of transmission in malaria endemic areas. Relapses contribute significantly to the challenges in controlling and eliminating vivax malaria. Historically, vivax malaria was considered rare or absent in Central and West Africa because of the dominance of Duffy-negative individuals, who lack expression of the Duffy Antigen Receptor for Chemokines (DARC) Pv required for erythrocyte invasion. However, there is growing evidence documenting Pv cases across different parts of Central and West Africa, beyond its endemic range in the Horn of Africa. Prior studies provide compelling evidence that Duffy negativity is not a definitive barrier to Pv invasion and the potential of widespread Pv transmission within Africa. Relapses are known to account for a high proportion of recurrent Pv infections across diverse geographic locations. In Africa, Pv is understudied and at the public health front-end, Pv infections are vastly overlooked in large parts of Africa. Despite numerous reports of Pv cases in Duffy negatives from West and Central Africa, most malaria cases in health facilities are considered as Pf and treated with artemisinin-based combination therapy (ACT). Information on the frequency and transmission potential of Pv relapses in Duffy negative Africans are largely unknown. This knowledge gap is highly significant as it limits malaria control policy in Africa and weakens U.S. preparedness for imported and relapsing Pv malaria among travelers, military personnel, and other mobile populations returning from Africa. This R21 application will address 1) what proportion of Pv infections has relapses, 2) how often (i.e. periodicity) relapses occur, 3) are relapse parasites genetically more diverse than those in primary infections, and 4) does relapse infection lead to transmission. Because relapsing infections are important drivers of transmission of Pv malaria, the proportion of recurrences caused by relapse and gametocyte carriage of relapse infections are critical to existing malaria diagnosis and antimalarial treatment regimens in Central/West Africa. For the U.S., the study will improve preparedness for imported and relapsing Pv malaria, inform clinical recognition of Pv acquired in Africa, strengthen surveillance strategies for recurrent malaria, and support public health readiness in the rare but plausible setting of local transmission following imported infection. Our prior study in Buea of Cameroon showed ~10% of febrile malaria cases and ~15% of asymptomatic community samples being Pv and all were from Duffy-negative individuals. This study will employ a longitudinal design to follow up a cohort of Pv-infected individuals with ACT and without antimalarial treatment to systematically examine relapse biology of Pv in Duffy-negative individuals in Cameroon, an understudied region.


Issue Date FY	Funding FY	Legal Entity Name	Legal Entity Address	Legal Entity City	Legal Entity State	Legal Entity Zip Code	Legal Entity COUNTY	Legal Entity COUNTRY	Assistance Listing	Award Code	Budget Year	Action Date	Action Type	Action Amount

Issue Date FY: 2026 ( Subtotal = $206,292 )
2026	2026	DREXEL UNIVERSITY	3141 CHESTNUT ST	PHILADELPHIA	PA	19104	PHILADELPHIA	USA	Allergy and Infectious Diseases Research	000	2	8/18/2026	NON-COMPETING CONTINUATION	$149,808
2026	2026	DREXEL UNIVERSITY	3141 CHESTNUT ST	PHILADELPHIA	PA	19104	PHILADELPHIA	USA	Allergy and Infectious Diseases Research	001	2	8/27/2026	SUPPLEMENT FOR EXPANSION	$56,484
														Subtotal = $206,292

Issue Date FY: 2025 ( Subtotal = $190,261 )
2025	2025	DREXEL UNIVERSITY	3141 CHESTNUT ST	PHILADELPHIA	PA	19104	PHILADELPHIA	USA	Allergy and Infectious Diseases Research	000	1	8/25/2025	NEW	$140,257
2025	2025	DREXEL UNIVERSITY	3141 CHESTNUT ST	PHILADELPHIA	PA	19104	PHILADELPHIA	USA	Allergy and Infectious Diseases Research	001	1	9/3/2025	SUPPLEMENT FOR EXPANSION	$50,004
														Subtotal = $190,261

Grand Total All Awards = $396,553

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A longitudinal cohort study of Plasmodium vivax relapses in Central Africa

Award Number: R21AI190606

ORGANIZATION: NATIONAL INSTITUTE OF ALLERGY & INFECTIOUS DISEASES

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)

PERIOD OF PERFORMANCE START DATE: 08/25/2025

PERIOD OF PERFORMANCE END DATE: 07/31/2027

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