Institutions based in two malaria-endemic countries, Brazil and Peru, are partnering with a leading research group in the USA with the long-term goal of providing scientific evidence that can be translated into effective public health interventions for malaria control in Amazonia. To determine whether asymptomatic parasite carriage is a major contributor to malaria transmission across the region, we aim: (a) to estimate the prevalence, incidence and risk factors for asymptomatic malaria parasite carriage in rural Amazonia; (b) to estimate the prevalence, incidence, average duration and risk factors for gametocyte carriage; (c) to compare the ability of symptomatic and asymptomatic carriers of gametocytes to experimentally infect wild caught local vectors; (d) to compare prospectively the risk of subsequent clinical malaria among asymptomatic parasite carriers and non-infected controls living in the same communities and to determine whether these episodes are due to persistent parasite lineages or to new infections; and (e) to test whether intra-host competition of genetically distinct parasite clones contributes to increased parasite virulence, greater risk of disease, and increased gametocyte production.
These aims will be achieved with population based surveys, using uniformized clinical and laboratory protocols, in three epidemiologically diverse Amazonian settings: (a) a typical agricultural settlement with endemic malaria transmission in Brazil, (b) periurban villages in Peru that became recently exposed to epidemic malaria, and (c) gold-mining enclaves in Peru with explosive malaria outbreaks due to P. vivax. The field-based clinical and epidemiological analysis will be complemented with measurements of immunological parameters, extensive parasite genotyping and experimental infections of mosquitoes through membrane-feeding assays, providing a unique multidisciplinary perspective on the public health significance of asymptomatic parasite carriage in the Amazon Basin. Of crucial importance, the infrastructure and the data resulting of seven years of active malaria surveillance in the field sites will establish the bases for the vector biology and pathogenesis components of this proposal and for implementing future malaria vaccine trials in the Amazon region.

Public Health Relevance

At a time when eradication is advocated as the ultimate goal of malaria control strategies worldwide, it remains unclear why malaria proved so difficult to control in areas of relatively low levels of transmission across the Amazon Basin. We hypothesize that asymptomatic infections may represent a major reservoir of parasites in this region, which is not addressed by traditional malaria control strategies.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Program--Cooperative Agreements (U19)
Project #
4U19AI089681-07
Application #
9105346
Study Section
Special Emphasis Panel (ZAI1)
Project Start
Project End
Budget Start
2016-07-01
Budget End
2017-06-30
Support Year
7
Fiscal Year
2016
Total Cost
Indirect Cost
Name
University of California San Diego
Department
Type
DUNS #
804355790
City
La Jolla
State
CA
Country
United States
Zip Code
92093
Rodrigues, Priscila T; Valdivia, Hugo O; de Oliveira, Thais C et al. (2018) Human migration and the spread of malaria parasites to the New World. Sci Rep 8:1993
Moreno, Marta; Tong-Rios, Carlos; Orjuela-Sanchez, Pamela et al. (2018) Continuous Supply of Plasmodium vivax Sporozoites from Colonized Anopheles darlingi in the Peruvian Amazon. ACS Infect Dis 4:541-548
Prussing, Catharine; Moreno, Marta; Saavedra, Marlon P et al. (2018) Decreasing proportion of Anopheles darlingi biting outdoors between long-lasting insecticidal net distributions in peri-Iquitos, Amazonian Peru. Malar J 17:86
Martin, Thomas C S; Vinetz, Joseph M (2018) Asymptomatic Plasmodium vivax parasitaemia in the low-transmission setting: the role for a population-based transmission-blocking vaccine for malaria elimination. Malar J 17:89
Junqueira, Caroline; Barbosa, Camila R R; Costa, Pedro A C et al. (2018) Cytotoxic CD8+ T cells recognize and kill Plasmodium vivax-infected reticulocytes. Nat Med 24:1330-1336
Cowell, Annie N; Valdivia, Hugo O; Bishop, Danett K et al. (2018) Exploration of Plasmodium vivax transmission dynamics and recurrent infections in the Peruvian Amazon using whole genome sequencing. Genome Med 10:52
Schrum, Jacob E; Crabtree, Juliet N; Dobbs, Katherine R et al. (2018) Cutting Edge: Plasmodium falciparum Induces Trained Innate Immunity. J Immunol 200:1243-1248
White, Sara E; Harvey, Steven A; Meza, Graciela et al. (2018) Acceptability of a herd immunity-focused, transmission-blocking malaria vaccine in malaria-endemic communities in the Peruvian Amazon: an exploratory study. Malar J 17:179
Hirako, Isabella Cristina; Assis, Patrícia Aparecida; Hojo-Souza, Natália Satchiko et al. (2018) Daily Rhythms of TNF? Expression and Food Intake Regulate Synchrony of Plasmodium Stages with the Host Circadian Cycle. Cell Host Microbe 23:796-808.e6
Prussing, Catharine; Bickersmith, Sara A; Moreno, Marta et al. (2018) Nyssorhynchus dunhami: bionomics and natural infection by Plasmodium falciparum and P. vivax in the Peruvian Amazon. Mem Inst Oswaldo Cruz 113:e180380

Showing the most recent 10 out of 69 publications