South Africa | Development of a Molecular Detection Tool for Plasmodium falciparum Gametocytes for Transmission Surveillance
- Aug 1, 2025
- 2 min read
Shaping the agendato meet the malaria elimination end goal
10th Southern Africa Malaria Research Conference, 29-31 July 2025
Future Africa Campus, University of Pretoria | https://malariaconference.mrc.ac.za/
Nathan Calitz, Mariette van der Watt, Lyn-Marie Birkholtz, Taneshka Kruger, Megan Riddin and Dina Coertzen
Sub-Saharan Africa is currently experiencing a resurgence of disease, largely driven by the Covid-19 pandemic, climate change, and the emergence of Artemisinin combination therapy (ACT) resistant Plasmodium falciparum strains. This situation necessitates the urgent development of novel surveillance tools to prevent the loss of progress made in disease elimination over the past two decades. Malaria pathogenesis involves the rapid asexual replication cycles of P. falciparum parasites. However, to ensure parasite transmission to Anopheles mosquitoes, some parasites differentiate into non-replicative sexual gametocytes, which can be present at submicroscopic levels in both symptomatic and asymptomatic individuals.
In areas with low transmission and minimal host competition, parasites prioritise gametocytogenesis over asexual replication, leading to higher gametocyte densities that enhance transmission efficiency—especially in populations with low acquired immunity. While ACTs have been effective in reducing gametocyte populations, they do not fully eliminate these transmissible forms. The lack of reliable gametocyte-detection techniques means these reservoirs remain unmonitored, facilitating the spread of drug-resistant parasites and impeding malaria elimination efforts.
The Vhembe district in Limpopo province is regarded as a transmission “hot spot,” accounting for over 60% of malaria cases in South Africa. Low sporozoite densities and positive cases suggest that low transmission in this region is driven by unmonitored gametocyte reservoirs in both symptomatic and asymptomatic individuals. Our aim is to establish a robust protocol for detecting gametocyte-specific transcripts by qPCR in whole-blood samples. This technology will be employed to assess gametocyte carriage in samples from the Vhembe district. Following optimisation of PCR and qPCR conditions using in vitro-generated gametocytes, we have successfully quantified gametocytes from whole blood collected with microsampling devices.
The resulting data will facilitate geospatial cross-correlation of gametocyte carriers with local mosquito populations, advancing our understanding of transmission dynamics, aiding in the implementation of targeted interventions to block continuous parasite transmission, and contributing to sustainable malaria elimination.
