Broadly speaking, we aim to:
Previous studies have addressed these questions under experimental, controlled, and sometimes laboratory conditions. While evaluations of intervention efficacy are useful, understanding effectiveness in real-world settings is needed. In addition, most research has evaluated single interventions rather than ensembles of characteristics that contribute to population-level probability of transmission, infection, and disease. We will evaluate
- patterns of pathogen transmission and human host response,
- the effectiveness of multiple interventions on infection in different environments,
- the relationships between infection frequency/duration and disease severity, and
- the impacts of insecticide resistance and ITN quality and use on disease patterns,
all in a context where the findings will illuminate the underlying mechanisms.
In addition, we will
- Produce and provide knowledge of mechanisms or contexts underlying the success or failure of attempted malaria prevention and control activities, develop evidence-based recommendations, and provide a framework for the anticipated impacts of the recommendations.
We expect that our findings will suggest simple, comprehensible, and effective methods to reduce the force of transmission and diminish entomological inoculation rates (EIR) in this and similar highly-endemic malaria settings.
We will approach the question of the intransigence of malaria transmission in Malawi in the context of four different longitudinal, community-based surveys, and a qualitative study.
Project 1: One of the surveys (P1) is an epidemiology study designed to identify incidence of malaria infection and disease, i.e., transmission of malaria from mosquitoes to humans This study incorporates entomological studies of mosquito behavior and documents insecticide resistance. We will also identify the significance of local environmental features (land use/land cover, climate variability, elevation) to the risk of transmission.
Project 2: Another (P2) is a study that focuses on transmission from humans to mosquitoes. We will identify gametocyte reservoirs, and in a separate study, their associated infectiousness. We will be looking for non-random contact between human hosts and Anopheles vectors which facilitate ready access of mosquitoes to gametocyte-infected reservoirs, especially school age children.
Both Project 1 and Project 2 will be carried out in the context of national distribution programs of different types of insecticide-treated bed nets (ITN) and will thus be positioned to capture data related to their effectiveness. Together, they will address these specific questions:
- Why do insecticide treated nets (ITNs) seem to have provided so little protection in Malawi?
- How much do asymptomatic, submicroscopically infectious people contribute to transmission there?
- Does insecticide resistance in Anopheles vectors affect their feeding behavior or ITN effectiveness?
- Are environmental factors (climate, geography, vegetation) so suitable to vector abundance and survival that interventions have little effect? 34
- How do these more common risk factors interact with other social, economic and behavioral drivers?
Project 3: The third longitudinal study (P3) involves children with asymptomatic parasitemia. It is unrelated to the ITN distribution activity and will compare putative factors related to progression along the spectrum from asymptomatic infection à malaria illness à life-threatening malaria disease.
Risk factors for and determinants of this evolution are unknown, and previous studies have been limited because:
- the subjects were not drawn from individuals at the far ends of the spectrum (sustained asymptomatic parasitemia, stringently defined cerebral malaria); and
- comparisons between the asymptomatic parasitemic individuals and those with malaria disease have been cross-sectional rather than longitudinal, obviating the possibility of identifying determinants and risk factors within individuals.
Project 4: Our fourth longitudinal study (P4) evaluates the impact of the RTS,S malaria vaccine, with and without ITNs and indoor residual spraying (IRS) on malaria transmission. This “Vaccine and Net Surveillance Study” (VANSS) involves cross-sectional longitudinal epidemiological and entomological studies to assess the impact of vaccination and PBO nets on malaria infection and transmission, when introduced together or independently.
Mosquito populations will be analyzed for phenotypic, biochemical, and genotypic attributes associated with permethrin resistance, and results compared between districts and over time after roll-out. Quantitative assessments of ITN use and qualitative analyses of behavior and perception will augment our cost-effectiveness analysis of PBO nets and vaccination
Project 5: Our final project is a qualitative study of barriers to the implementation of malaria control and prevention and includes input from the grass roots up to policy makers. This study seeks to examine and understand factors associated with malaria prevention across the different age groups, especially among school-age children (SAC) in Malawi.
Specific objectives are to:
COVID-19 is currently a public health threat and emergency in Malawi. We therefore would like to capitalize on the opportunity this study provides to explore these specific COVID-19 related aims:
- To assess knowledge, perceptions, and practices of SAC, care givers and key community leaders toward COVID-19 and how its prevention strategies affect use of key malaria interventions.
- Evaluate the psychosocial, and perceived economic impact of COVID-19 on SAC, parents and general public.
By virtue of our comprehensive approach to malaria transmission, malaria infection and malaria disease, we expect to identify the major drivers of each, and in the process, improve the national efforts to control and prevent this scourge.
The projects are supported by five cores:
- Molecular Parasitology and Genomics
- Data Management and Biostatistics
- Information Technology (IT).
The current NIH grant runs from 2017 – 2024.