Malawi ICEMR: Accelerating Malaria Prevention Through Enhanced Analysis of Transmission and RTS,S Vaccination in Malawi

Lead Institution: Kamuzu University of Health Sciences

Background

Malaria control in Malawi is stagnating because the vectors are becoming increasingly resistant to insecticides and biting at times and places where LLINs are not used. To counter this, the Malawi government is introducing new and improved malaria interventions such as "dual active-ingredient" long-lasting insecticidal nets (dual-AI LLIN) and the RTS,S vaccine. The Malawi ICEMR is in a unique position to study the impacts of both of these in relation to different environmental and behavioral drivers of malaria parasite transmission. The overall goal of this ICEMR is aimed at improving and augmenting current malaria control efforts in Malawi, through collaborative and coordinated studies of the mosquito vector (its behavior and population ecology) and the human host (exposure, infection, malaria disease).

Projects

Transmission Project

The Malawi ICEMR will evaluate the effects of dual-AI LLINs on the abundance and biting behavior of malaria vectors in Malawi. These outcomes will be measured across a range of biogeographical settings to assess the role of environmental factors in modulating vector control effectiveness. Data will be prospectively collected from 18 ICEMR sites across seven districts in the Southern Region and from seven of the National Malaria Control Program (NMCP) sentinel sites. Vector biting patterns will be combined with assessments of human behaviors and measures of human infection and disease from the Epidemiology Project to determine how differences in exposure affect the epidemiology of infection and disease.

Epidemiology Project

The Ministry of Health in Malawi has now rolled out routine RTS,S vaccination programs across 11 districts of Malawi. The Malawi ICEMR will address questions related to longer-term effects of the RTS,S vaccine such as 1) What is the impact of the vaccine on subsequent malaria infection and uncomplicated malaria?; and 2) Does early vaccination prevent or allow older children to develop better immunity that will protect them from future infection and disease?

The Epidemiology Project will use a combination of longitudinal household surveys and enhanced surveillance in areas with and without RTS,S roll-out. In addition, hospital level surveillance for severe malaria will be conducted in areas with and without vaccine availability. The Epidemiology projects will take place in 36 health centers and their surrounding catchment areas across seven districts of southern Malawi. These districts were selected because they are biogeographically diverse and have population prevalence rates of malaria infection ranging from low to medium to high. See Figure 1 below. Five of the seven districts have rolled out the RTS,S vaccine.

Key Findings From Previous ICEMRs

The Malawi ICEMR has been funded by the NIH for the last 14 years, and has built a critical mass of researchers in Malawi. It has established field and laboratory infrastructure that are able to support several malaria research projects. Key findings from the previous ICEMR have informed the current ICEMR's research areas; examples include:

  1. Ninety percent of P. falciparum infections are asymptomatic and prevalence peaks in school-aged children (Coalson, 2016).
  2. The peak prevalence of infection in school-age children has both biological (acquired immunity) and socio-behavioral (access to malaria interventions) underpinnings.
  3. School-age children are key reservoirs of human-to-mosquito parasite transmission (Walldorf, 2015).
  4. Schools based interventions are possible to reduce the burden of malaria in school-age children (Cohee, 2012).
  5. The integrity (insecticide potency and physical) of LLINs deteriorate after LLIN mass campaign (Andronescu, 2019).
  6. Pyrethroid resistance is widespread and is worsening in Malawi indicating urgent need for new approaches to vector control (Mzilahowa, 2015).

Impact of Previous ICEMRs in Malawi

ICEMR findings have influenced national malaria policy. During this time, the ICEMR has forged and consolidated strong collaborations with the NMCP and other implementing partners such as the President’s Malaria Initiative, USAID, CDC, World Vision and UNICEF. From the results of the ICEMR, key changes to the national malaria policy include:

  1. Decreasing the interval between mass LLIN distributions from three to two years. The rapid deterioration of insecticide potency and physical integrity and its impact on LLIN effectiveness which the ICEMR team demonstrated has led to a major policy shift, in which the Malawi NMCP will now conduct mass distribution campaigns every two years starting in 2021, instead of every three years as in previous campaigns.
  2. Including strategies targeting school-aged children in the Malawi Malaria Strategic Plan 2023 – 2030. The ICEMR has shown that the highest burden of infection is in school-aged children and has identified them as major contributors to transmission underpinnings. These findings have led to inclusion of the school-aged children as a target for malaria control in the new malaria strategic plan with an emphasis on finding novel interventions to reach this group with key interventions.
  3. Adopting malaria stratification in the distribution of interventions. Malawi has previously not adopted stratified malaria control program because of the assumption that the entire population is at a high risk of infection. ICEMR research showed that there is limited transmission in some settings, such as urban settings. This led to urban areas not being included in the 2021 mass distribution campaign and the adoption of stratification-based interventions for the Malaria Strategic Plan 2023 – 2030.

Impact of the ICEMR

The long-term significance of the current Malawi ICEMR is to help the global community to: (a) understand the long-term impact of the current RTS,S vaccine, and other potential malaria vaccines, (b) assess the effectiveness of dual-AI LLINs on reducing malaria parasite transmission and disease burden.

Study Sites

View Associated sites for the Malawi ICEMR in a larger map

Map description: Sites associated with the Malawi ICEMR: Districts of Balaka, Machinga, Mangochi, Phalombe, Chikwawa, Blantyre, Zomba

Collaborating Institutions

  • University of Maryland School of Medicine, Baltimore MD
  • Liverpool School of Tropical Medicine
  • Michigan State University
  • Boston University School of Public Health
  • Harvard T.H. Chan School of Public Health
  • University of Michigan

Staff

Principal Investigator: Don Mathanga, MBBS, PhD, Kamuzu University of Health Sciences

Project Leads

Transmission Project

  • Robert McCann PhD, University of Maryland School of Medicine 
  • Themba Mzilahowa PhD, Kamuzu University of Health Sciences

Epidemiology Project

  • Lauren Cohee MD, Liverpool School of Tropical Medicine
  • Christopher Stanley, PhD, Kamuzu University of Health Sciences
  • Charles Mangani, MBBS, PhD, Kamuzu University of Health Sciences
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