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Impact of declining transmission on immunity and risk of malaria rebound

Many trials of interventions to control and prevent malaria have reported rebounds in transmission following an initial period of reduced malaria incidence and mortality. Rebounds malaria have been attributed to a perceived loss of naturally acquired immunity during the period of reduced exposure. However, at present, there is no quantifiable data from studies assessing both the impact of mass drug administration and its effect on naturally acquired antimalarial immunity.

To achieve the goal of complete elimination of malaria from the Greater Mekong Subregion of Southeast Asia by the year 2030, the World Health Organisation now supports mass drug administration in selected high risk populations. Mass drug administration could be particularly effective in this region to eliminate asymptomatic reservoirs of Plasmodium spp. infection, however there is hesitancy to adopt widescale use of mass drug administration to eliminate malaria over fears of drug resistance selection and its impact on population level antimalarial immunity. Although increases in malaria-associated morbidity following large-scale elimination campaigns have been attributed to a loss of population level antimalarial immunity, and therefore susceptibility to clinical illness, there is little quantifiable evidence of this loss of immunity.


Utilising data from malaria intervention trials in the Greater Mekong Subregion, we seek to quantify the impact of malaria control measures including the potential elimination on malaria immunity within communities and how this affects the long-term transmission of malaria and the risk of clinical or subclinical infection rebound. Additionally, we seek to understand the association between subclinical infection and the maintenance of antimalarial immunity in this population.

This study will quantify the impact of Mass Drug Administration on antimalarial immunity and provide time frames to identify populations at risk of malaria rebound and establishment of submicroscopic infectious reservoirs of parasites. Findings are essential for guiding policy recommendations, the allocation of resources for the prevention of malaria rebound, and achieving malaria elimination in the Greater Mekong Subregion.

Freya Fowkes

Professor Freya J.I. Fowkes

Contact Professor Freya J.I. Fowkes to find out more information about the project.



  • National Health and Medical Research Council

Partners +

  • Shoklo Malaria Research Unit, Thailand
  • Mahidol Oxford Research Unit, Thailand
  • The University of Melbourne, Australia
  • The Walter and Eliza Hall Institute