Prévalence des délétions des gènes pfhrp2 et pfhrp3 chez Plasmodium falciparum sur le plateau des Guyanes

Abstract : Since 2009, World Health Organization (WHO) recommends the biological diagnostic confirmation by either microscopy or rapid diagnostic test (RDT) of any clinical malaria cases before delivering appropriate antimalarial treatment. This recommendation led to increasing use of RDTs especially in remote areas with limited infrastructures. Most RDTs target the histidine-rich protein-2 antigen (PfHRP2) to detect Plasmodium falciparum. However, parasites deleted for the pfhrp2 gene encoding this protein have been described in Amazonia. The risk is then to misdiagnosed a P. falciparum case as a P. vivax one and to treat it with chloroquine. In the Guiana Shield, 20 to 30% of parasites are chloroquino-resistant. Due to human migration and the importance of RDTs in this region, increased surveillance of pfhrp2 deletion is required. Thus, isolates collected between 2015 and 2017 in French Guiana, Guyana and Venezuela were studied according to WHO recommendations to estimate the prevalence of parasites lacking the pfhrp2 and pfhrp3 genes. Eight amplifications analyzed two regions of the genes pfhrp2 and pfhrp3, junction exon 1-2 and exon 2, of the genes and their flanking genes. To assess the sample DNA quality and quantity and to select suitable isolates for molecular analysis, the protocol included a real-time PCR as a semi-quantitative method. A total of 690 isolates were analyzed. In Venezuela, 39% (IC95 [28.1 - 49.9]) of the parasites were pfhrp3 negative and 2.6% (IC95 [0-6.8]) pfhrp2 negative. In Guyana (n = 265) and French Guiana (n = 230), no parasite lacked the pfhrp2 gene and respectively 3.0% IC95 [0.9% - 5.1%] and 0.5% IC95 [0 - 1.5] were pfhrp3 negative. These robust data identify for the first time the presence of deleted pfhrp2 parasites in Venezuela and confirm their absence in Guyana and French Guiana. Therefore surveillance remains important in Venezuela. However, Pf-HRP2-based RDTs remain suitable diagnostic tools in the countries of this region.
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Master Thesis
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Léna Berthelot. Prévalence des délétions des gènes pfhrp2 et pfhrp3 chez Plasmodium falciparum sur le plateau des Guyanes. Parasitologie. 2018. ⟨dumas-02018247⟩

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