{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,29]],"date-time":"2026-06-29T04:23:44Z","timestamp":1782707024010,"version":"3.54.5"},"reference-count":33,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2021,9,8]],"date-time":"2021-09-08T00:00:00Z","timestamp":1631059200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Cell. Infect. Microbiol."],"abstract":"<jats:sec><jats:title>Background<\/jats:title><jats:p>Sulfadoxine-pyrimethamine (SP) is recommended for intermittent preventive treatment in Africa against <jats:italic>Plasmodium falciparum<\/jats:italic> infection. However, increasing SP resistance (SPR) of <jats:italic>P. falciparum<\/jats:italic> affects the therapeutic efficacy of SP, and <jats:italic>pfdhfr<\/jats:italic> (encoding dihydrofolate reductase) and <jats:italic>pfdhps<\/jats:italic> (encoding dihydropteroate synthase) genes are widely used as molecular markers for SPR surveillance. In the present study, we analyzed single nucleotide polymorphisms (SNPs) of <jats:italic>pfdhfr<\/jats:italic> and <jats:italic>pfdhps<\/jats:italic> in <jats:italic>P. falciparum<\/jats:italic> isolated from infected Chinese migrant workers returning from Africa.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>In total, 159 blood samples from <jats:italic>P. falciparum<\/jats:italic>-infected workers who had returned from Africa to Anhui, Shangdong, and Guangxi provinces were successfully detected and analyzed from 2017 to 2019. The SNPs in <jats:italic>pfdhfr<\/jats:italic> and <jats:italic>pfdhps<\/jats:italic> were analyzed using nested PCR. The genotypes and linkage disequilibrium (LD) were analyzed using Haploview.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>High frequencies of the Asn51Ile (N51I), Cys59Arg(C59R), and Ser108Asn(S108N) mutant alleles were observed, with mutation frequencies of 97.60, 87.43, and 97.01% in <jats:italic>pfdhfr<\/jats:italic>, respectively. A triple mutation (IRN) in <jats:italic>pfdhfr<\/jats:italic> was the most prevalent haplotype (86.83%). Six point mutations were detected in <jats:italic>pfdhps<\/jats:italic> DNA fragment, Ile431Val (I431V), Ser436Ala (S436A), Ala437Gly (A437G), Lys540Glu(K540E), Ala581Gly(A581G), Ala613Ser(A613S). The <jats:italic>pfdhps<\/jats:italic> K540E (27.67%) was the most predominant allele, followed by S436A (27.04%), and a single mutant haplotype (SGKAA; 62.66%) was predominant in <jats:italic>pfdhps<\/jats:italic>. In total, 5 haplotypes of the <jats:italic>pfdhfr<\/jats:italic> gene and 13 haplotypes of the <jats:italic>pfdhps<\/jats:italic> gene were identified. A total of 130 isolates with 12 unique haplotypes were found in the <jats:italic>pfdhfr-pfdhps<\/jats:italic> combined haplotypes, most of them (n = 85, 65.38%) carried quadruple allele combinations (CIRNI-SGKAA).<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>A high prevalence of point mutations in the <jats:italic>pfdhfr<\/jats:italic> and <jats:italic>pfdhps<\/jats:italic> genes of <jats:italic>P. falciparum<\/jats:italic> isolates was detected among Chinese migrant workers returning from Africa. Therefore, continuous <jats:italic>in vitro<\/jats:italic> molecular monitoring of Sulfadoxine-Pyrimethemine combined <jats:italic>in vivo<\/jats:italic> therapeutic\u00a0monitoring of artemisinin combination therapy (ACT) efficacy and additional control efforts among migrant workers are urgently needed.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fcimb.2021.673194","type":"journal-article","created":{"date-parts":[[2021,9,8]],"date-time":"2021-09-08T14:10:08Z","timestamp":1631110208000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":15,"title":["High Frequency Mutations in pfdhfr and pfdhps of Plasmodium falciparum in Response to Sulfadoxine-Pyrimethamine: A Cross-Sectional Survey in Returning Chinese Migrants From Africa"],"prefix":"10.3389","volume":"11","author":[{"given":"He","family":"Yan","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jun","family":"Feng","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jian-hai","family":"Yin","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fang","family":"Huang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiang-li","family":"Kong","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kang-ming","family":"Lin","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tao","family":"Zhang","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xin-yu","family":"Feng","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shui-sen","family":"Zhou","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jian-ping","family":"Cao","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhi-gui","family":"Xia","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2021,9,8]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"523","DOI":"10.4269\/ajtmh.2009.80.523","article-title":"Five-Year Surveillance of Molecular Markers of Plasmodium Falciparum Antimalarial Drug Resistance in Korogwe District, Tanzania: Accumulation of the 581G Mutation in the P. 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