Image

P2 - Reservoirs of transmission: Targets for Malaria Control Interventions

1) Systematically characterize human-to-mosquito transmission patterns to identify the important transmission reservoir group(s) for malaria in Malawi,

2) Assess the impact of current interventions on these human reservoirs,

3) Develop analytical models using these data to design and monitor targeted interventions to efficiently reduce transmission.




Characterizing the reservoirs of transmission will be accomplished by specific studies designed to enhance our understanding of:

In a cohort of ~120 participants sampled every  two weeks, we will use membrane feeding assays to evaluate infectiousness. We will evaluate the contributions of host (age, symptom status, infection history) and parasite  (gametocyte sex ratio and density) factors to infectiousness.
Using the characteristics of infectiousness defined in our membrane feeding studies (left), we will determine the population distribution of infections that are likely infectious. We have conducted active and passive case detection in all household members in 100 households in each of our study sites including monthly sample collection for diagnosis of malaria parasites and well as quantification of gametocyte sex ratio and density.  These results will be combined with assessments of who is bitten by mosquito vectors (right) to characterize the transmission reservoirs in our settings.
Among a subset of 50 households in the cohort of 100 households per study site, we have conducted intensive entomologic surveillance using pyrethrum spray catches and CDC light traps. Among the blood feed mosquitoes, we will use microsatellite genotyping to identify the human source of mosquito bloodmeals. Host characteristics and behaviors and use of interventions associated with successful blood feeding will be sought.

Investigators

Image

Clarissa Valim, M.D., Sc.D.
Project Leader
Research Associate Professor
Department of Global Health
Boston University School of Public Health

Image
Project Deputy Leader
Instructor
Center for Vaccine Development and Global Health
University of Maryland

Senior Advisors

Image
Professor
Center for Vaccine Development and Global Health
University of Maryland
Image

Mark Wilson, Sc.D.
Professor Emeritus
Department of Epidemiology
School of Public Health
University of Michigan

Study Team

Image

Jessy Goupeyou-Youmsi, Ph.D.
Post-doctoral Fellow
College of Medicine
University of Malawi

Image

Robert McCann, Ph.D.
Instructor
Center for Vaccine Development and Global Health
University of Maryland

This is title

Image
Associate Professor
College of Medicine
University of Malawi
Image

Edward D. Walker, Ph.D.
Professor
Department of Microbiology and Molecular Genetrics
Michigan State University

Study Team

Image

Jimmy Vareta
Ph.D. Candidate
University of Maryland

Image

Rex Mbewe
Ph.D. Candidate
Michigan State University

Project Location

  • Machinga
  • Balaka

Duration

2018-2024

Project Publications

  1. McCann RS, Cohee LM, Goupeyou-Youmsi J, Laufer MK. Maximizing Impact: Can Interventions to Prevent Clinical Malaria Reduce Parasite Transmission? Trends Parasitol. 2020;0. doi:10.1016/j.pt.2020.07.013.https://pubmed.ncbi.nlm.nih.gov/32917511/

  2. Buchwald AG, Walldorf JA, Cohee LM, Coalson JE, Chimbiya N, Bauleni A, et al. Bed net use among school-aged children after a universal bed net campaign in Malawi. Malar J. 2016;15:127. doi:10.1186/s12936-016-1178-9.  https://pubmed.ncbi.nlm.nih.gov/26928321/                                                        

  3.  Walldorf JA, Cohee LM, Coalson JE, Bauleni A, Nkanaunena K, Kapito-Tembo A, et al. School-Age Children Are a Reservoir of Malaria Infection in Malawi. PLoS One. 2015;10:e0134061. doi:10.1371/journal.pone.0134061. https://pubmed.ncbi.nlm.nih.gov/29615044/                               

  4.  Coalson JE, Cohee LM, Buchwald AG, Nyambalo A, Kubale J, Seydel KB, et al. Simulation models predict that school-age children are responsible for most human-to-mosquito Plasmodium falciparum transmission in southern Malawi. Malar J. 2018;17. doi:10.1186/s12936-018-2295-4.  https://pubmed.ncbi.nlm.nih.gov/27809907/                 

  5. Coalson JE, Walldorf JA, Cohee LM, Ismail MD, Mathanga D, Cordy RJ, et al. High prevalence of Plasmodium falciparum gametocyte infections in school-age children using molecular detection: patterns and predictors of risk from a cross-sectional study in southern Malawi. Malar J. 2016;15. doi:10.1186/s12936-016-1587-9.   https://pubmed.ncbi.nlm.nih.gov/27809907/