Molecular characterization of antimalarial resistance and hrp2/3 deletions in Plasmodium falciparum strains from Mtwara, Tanzania (2021-2024).
10 affiliations
- 1Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Rd., Ratchathewi, Bangkok, 10400, Thailand.
- 2Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Rd., Ratchathewi, Bangkok, 10400, Thailand.
- 3Department of Biochemistry, Faculty of Science, Kasetsart University, 50 Ngam Wong Wan Rd., Lat Yao, Chatuchak, Bangkok, 10900, Thailand.
- 4CSK Research Solutions, Mtwara, Tanzania.
- 5Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
- 6National Institute for Medical Research, 11101, Dar es Salaam, Tanzania.
- 7Department of Biochemistry, Kampala International University in Tanzania, Dar es Salaam, Tanzania.
- 8Centre for Tropical Medicine and Global Health, Churchill Hospital, University of Oxford, Oxford, UK.
- 9Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Rd., Ratchathewi, Bangkok, 10400, Thailand. [email protected].
- 10Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Rd., Ratchathewi, Bangkok, 10400, Thailand. [email protected].
Abstract
Background
Malaria remains a significant public health challenge in sub-Saharan Africa and Southeast Asia, with Plasmodium falciparum responsible for the majority of infections and deaths, particularly among children aged < 5 years. In Tanzania, the widespread use of antimalarial drugs, such as sulfadoxine-pyrimethamine for preventive therapy and artemisinin-based combination therapies as first-line treatment, has prompted concerns about the emergence and spread of drug resistance. The prolonged use of these drugs may have influenced resistance patterns, varying over time. Moreover, some P. falciparum samples have been reported as rapid diagnostic test (RDT)-negative despite microscopic confirmation of P. falciparum infection, raising questions about whether such false-negative results are due to poor-quality RDT kits or genetic deletions in the parasite.Methods
This study investigated drug resistance dynamics and potential false-negative RDT results in P. falciparum by analyzing molecular markers in pfdhps, pfdhfr, pfkelch13, and pfhrp2/3, with the 18S rRNA gene used as a housekeeping control to verify DNA quality and confirm true parasite positivity.Results
Molecular analysis revealed a decline in the triple pfdhfr mutation paired with double pfdhps mutations, alongside an increase in mixed dhfr-dhps haplotypes (χ² = 28.94, p < 0.001), indicating ongoing genetic diversification under drug pressure. Wild-type parasites were predominant (56-76%), and most pfkelch13 mutations were located in the non-propeller region, with no validated or candidate mutations associated with artemisinin-resistance detected. P. falciparum-infected samples that were RDT-negative showed a high frequency of both complete and partial deletions in pfhrp2 and pfhrp3, potentially explaining RDT inconsistencies and false-negative results.Conclusions
P. falciparum remains the dominant species in this high-transmission region, showing a persistently high rate of antifolate resistance. Significant associations between triple pfdhfr and double pfdhps resistance markers were observed between 2021 and 2024. The continued susceptibility to artemisinin emphasizes the need for ongoing molecular surveillance and monitoring of hrp2/hrp3 deletions to support malaria control strategies in Tanzania.
Related
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- Molecular Surveillance of Antimalarial Drug Resistance-Associated Mutations in P. falciparum Imported from Africa into Guangdong Province, China, 2023-2025.
- G-quadruplex-binding ligand RHPS4 reduces Plasmodium falciparum mitochondrial DNA level providing a novel antimalarial strategy
- Spatial surveillance of Plasmodium falciparum Kelch 13 mutations reveals High-Frequency A675V and the First Molecular Evidence of Suspected Partial Artemisinin Resistance in Baringo in Kenya.
- Global trends in the burden of malaria: mapping the prevalence, incidence and mortality of Plasmodium falciparum and Plasmodium vivax in the era of climate change and emerging drug resistance.
BibTeX
@article{thapradit2026molecular,
title = {{Molecular characterization of antimalarial resistance and hrp2/3 deletions in Plasmodium falciparum strains from Mtwara, Tanzania (2021-2024).}},
author = {Piyathida Thapradit and Watcharee Pagornrat and Wanassanan Madmanee and Raweewan Sangsri and Kiattawee Choowongkomon and Salum Mshamu and Deus S Ishengoma and Arjen M Dondorp and Lorenz Von Seidlein and Mallika Imwong},
journal = {Malaria journal},
year = {2026},
month = jul,
doi = {10.1186/s12936-026-06028-2},
url = {https://europepmc.org/article/MED/42928299},
note = {CC BY},
}
RIS
TY - JOUR
TI - Molecular characterization of antimalarial resistance and hrp2/3 deletions in Plasmodium falciparum strains from Mtwara, Tanzania (2021-2024).
AU - Piyathida Thapradit
AU - Watcharee Pagornrat
AU - Wanassanan Madmanee
AU - Raweewan Sangsri
AU - Kiattawee Choowongkomon
AU - Salum Mshamu
AU - Deus S Ishengoma
AU - Arjen M Dondorp
AU - Lorenz Von Seidlein
AU - Mallika Imwong
PY - 2026
DA - 2026/07/01
JO - Malaria journal
DO - 10.1186/s12936-026-06028-2
UR - https://europepmc.org/article/MED/42928299
AB - Background Malaria remains a significant public health challenge in sub-Saharan Africa and Southeast Asia, with Plasmodium falciparum responsible for the majority of infections and deaths, particularly among children aged < 5 years. In Tanzania, the widespread use of antimalarial drugs, such as sulfadoxine-pyrimethamine for preventive therapy and artemisinin-based combination therapies as first-line treatment, has prompted concerns about the emergence and spread of drug resistance. The prolonged use of these drugs may have influenced resistance patterns, varying over time. Moreover, some P. falciparum samples have been reported as rapid diagnostic test (RDT)-negative despite microscopic confirmation of P. falciparum infection, raising questions about whether such false-negative results are due to poor-quality RDT kits or genetic deletions in the parasite.Methods This study investigated drug resistance dynamics and potential false-negative RDT results in P. falciparum by analyzing molecular markers in pfdhps, pfdhfr, pfkelch13, and pfhrp2/3, with the 18S rRNA gene used as a housekeeping control to verify DNA quality and confirm true parasite positivity.Results Molecular analysis revealed a decline in the triple pfdhfr mutation paired with double pfdhps mutations, alongside an increase in mixed dhfr-dhps haplotypes (χ² = 28.94, p < 0.001), indicating ongoing genetic diversification under drug pressure. Wild-type parasites were predominant (56-76%), and most pfkelch13 mutations were located in the non-propeller region, with no validated or candidate mutations associated with artemisinin-resistance detected. P. falciparum-infected samples that were RDT-negative showed a high frequency of both complete and partial deletions in pfhrp2 and pfhrp3, potentially explaining RDT inconsistencies and false-negative results.Conclusions P. falciparum remains the dominant species in this high-transmission region, showing a persistently high rate of antifolate resistance. Significant associations between triple pfdhfr and double pfdhps resistance markers were observed between 2021 and 2024. The continued susceptibility to artemisinin emphasizes the need for ongoing molecular surveillance and monitoring of hrp2/hrp3 deletions to support malaria control strategies in Tanzania.
SN - 1475-2875
ER -