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Background: Sulfadoxine-pyrimethamine (SP) is recommended for intermittent preventive treatment in Africa against Plasmodium falciparum infection. However, increasing SP resistance (SPR) of P. falciparum affects the therapeutic efficacy of SP, and pfdhfr (encoding dihydrofolate reductase) and pfdhps (encoding dihydropteroate synthase) genes are widely used as molecular markers for SPR surveillance. In the present study, we analyzed single nucleotide polymorphisms (SNPs) of pfdhfr and pfdhps in P. falciparum isolated from infected Chinese migrant workers returning from Africa. Methods: In total, 159 blood samples from P. falciparum -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 pfdhfr and pfdhps were analyzed using nested PCR. The genotypes and linkage disequilibrium (LD) were analyzed using Haploview. Results: 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 pfdhfr , respectively. A triple mutation (IRN) in pfdhfr was the most prevalent haplotype (86.83%). Six point mutations were detected in pfdhps DNA fragment, Ile431Val (I431V), Ser436Ala (S436A), Ala437Gly (A437G), Lys540Glu(K540E), Ala581Gly(A581G), Ala613Ser(A613S). The pfdhps K540E (27.67%) was the most predominant allele, followed by S436A (27.04%), and a single mutant haplotype (SGKAA; 62.66%) was predominant in pfdhps. In total, 5 haplotypes of the pfdhfr gene and 13 haplotypes of the pfdhps gene were identified. A total of 130 isolates with 12 unique haplotypes were found in the pfdhfr-pfdhps combined haplotypes, most of them (n = 85, 65.38%) carried quadruple allele combinations (CIRNI-SGKAA). Conclusion: A high prevalence of point mutations in the pfdhfr and pfdhps genes of P. falciparum isolates was detected among Chinese migrant workers returning from Africa. Therefore, continuous in vitro molecular monitoring of Sulfadoxine-Pyrimethemine combined in vivo therapeutic monitoring of artemisinin combination therapy (ACT) efficacy and additional control efforts among migrant workers are urgently needed. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effect of malaria surveillance and control of Guangxi Zhuang Autonomous Region in 2013, and explore the suited surveillance and management of imported malaria cases, so as to provide the evidence for formulating the scientific control measures of imported malaria., Methods: The endemic data and control measures of malaria in Guangxi in 2013 were collected and analyzed statistically., Results: A total of 1 251 malaria cases were found in Guangxi in 2013, with 88.25% (1,104 cases) of falciparum malaria, 8.63% (108 cases) of vivax malaria, 0.64% (8 cases) of quartan malaria, 1.52% (19 cases) of ovale malaria, and 0.96% (12 cases) of mixed infection; 93.21% (1 166 cases) were off-farm workers; 96.56% (1,208 cases) were imported from Africa and mainly consisted of falciparum malaria cases; 3.44% (43 cases) were imported from southeast Asia and mainly consisted of vivax malaria cases. The cases of imported malaria were increasing and the infection rate in 2013 was increased by 464% compared with that in 2012., Conclusion: The imported malaria cases in Guangxi mainly come from Africa at present. Promoting the health education and professional skill of malaria control and treatment, as well as the diagnosis and treatment of the patients in early time are important measures to control the imported malaria.