Observational studyMalaria journal2015
Prevalence of Plasmodium falciparum anti-malarial resistance-associated polymorphisms in pfcrt, pfmdr1 and pfnhe1 in Muheza, Tanzania, prior to introduction of artemisinin combination therapy.
Observational study in Malaria journal, 2015. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 8 papers, 1 of them a synthesis that pooled it.
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Who cites it
8 citing papers in PubMed, 1 synthesis or guideline pooled it, 13 citations in OpenAlex.
- Persistence of chloroquine resistance alleles in malaria endemic countries: a systematic review of burden and risk factors.Malaria journal · 2019Pooled it
- Trial
- Molecular surveillance for polymorphisms associated with artemisinin-based combination therapy resistance in Plasmodium falciparum isolates collected in Mozambique, 2018.Malaria journal · 2021Article
- Molecular surveillance of Pfcrt and k13 propeller polymorphisms of imported Plasmodium falciparum cases to Zhejiang Province, China between 2016 and 2018.Malaria journal · 2020Article
- Analysis of Plasmodium falciparum Pfcrt and Pfmdr1 genes in parasite isolates from asymptomatic individuals in Southeast Nigeria 11 years after withdrawal of chloroquine.Malaria journal · 2019Article
- Analysis of Plasmodium falciparum NaBMC infectious diseases · 2019Article
- The Malaria TaqMan Array Card Includes 87 Assays for Plasmodium falciparum Drug Resistance, Identification of Species, and Genotyping in a Single Reaction.Antimicrobial agents and chemotherapy · 2017Article
- Disease burden and the role of pharmacogenomics in African populations.Global health, epidemiology and genomics · 2017Review
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8 authors at 2 institutions in 2 countries.
Funding
Abstract
backgroundA report of the chloroquine and amodiaquine resistance pfcrt-SVMNT haplotype in Tanzania raises concern about high-level resistance to the artesunate-amodiaquine combination treatment widely employed in Africa. Mutations in the pfmdr1 multi-drug resistance gene may also be associated with resistance, and a highly polymorphic microsatellite (ms-4760) of the pfnhe1 gene involved in quinine susceptibility has not been surveyed in Tanzania.
methodsA total of 234 samples collected between 2003 - 2006 from an observational birth cohort of young children in Muheza, Tanzania were analysed. In these children, 141 cases of P. falciparum infections were treated with AQ and 93 episodes were treated with QN. Haplotypes of pfcrt and pfmdr1 were determined by a Taqman assay, and ms-4760 repeats in pfnhe1 were assessed by nested PCR amplification and direct sequencing. Parasite population diversity was evaluated using microsatellite markers on five different chromosomes.
resultsThe pfcrt-CVIET haplotype was present alone in 93.6% (219/234) of the samples over the study period; the wild-type chloroquine- and amodiaquine-sensitive haplotype pfcrt-CVMNK was present in 4.3% (10/234) of the samples; and both haplotypes were present in 2.1% (5/234) of the samples. No significant change in wild-type pfcrt-CVMNK prevalence was evident over the 4-year period of the study. The pfcrt-SVMNT haplotype associated with high-level amodiaquine resistance was not detected in this study. The pfmdr1 locus was genotyped in 178 of these samples. The pfmdr1-YYNY haplotype predominated in 67.4% (120/178) of infections and was significantly associated with the pfcrt-CVIET haplotype. All samples carried the wild-type pfmdr1-N1042 codon. The ms-4760 repeat on pfnhe1 locus displayed 12 distinct haplotypes with ms-4760-1 predominating in the population. Analysis of these haplotypes showed no association of a particular haplotype with quinine treatment outcome.
conclusionThe pfcrt-CVIET chloroquine resistance haplotype dominated in the collection of P. falciparum samples from Muheza. The pfcrt-SVMNT haplotype, which threatens the efficacy of amodiaquine and was reported in the same time period from Korogwe, Tanzania, 40 Km from Muheza, was not detected. Relative low prevalence of pfcrt-SVMNT in Africa may result from genetic or other factors rendering P. falciparum less supportive of this haplotype than in South America or other regions.
trial registrationTrial Protocol Number: 08-I-N064.
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