Background The emergence and spread of multidrug resistance poses a significant risk to malaria control and eradication goals in the world. There has been no indigenous malaria cases reported in China since 2017, and China is approaching national malaria elimination. Therefore, anti-malarial drug resistance surveillance and tracking the emergence and spread of imported drug-resistant malaria cases will be necessary in a post-elimination phase in China. Methods Dried blood spots were obtained from Plasmodium falciparum-infected cases returned from Africa to China between 2012 and 2015, prior to anti-malarial drug treatment. Whole DNA were extracted and known polymorphisms relating to drug resistance of pfcrt, pfmdr1 gene, and the propeller domain of pfk13 were evaluated by nested PCR and sequencing. The haplotypes and prevalence of these three genes were evaluated separately. Chi-squared test and Fisher's exact test were used to evaluate differences among the different sub-regions of Africa. A P value < 0.05 was used to evaluate differences with statistical significance. The maps were created using ArcGIS. Results A total of 731 P. falciparum isolates were sequenced at the pfcrt locus. The wild type CVMNK was the most prevalent haplotype with prevalence of 62.8% and 29.8% of the isolates showed the triple mutant haplotype CVIET. A total of 434 P. falciparum isolates were successfully sequenced and pfmdr1 allelic variants were observed in only codons 86, 184 and 1246. Twelve haplotypes were identified and the prevalence of the wild type pfmdr1 NYD was 44.1%. The single mutant pfmdr1 in codons 86 and 184 was predominant but the haplotype NYY with single mutation in codon 1246 was not observed. The double mutant haplotype YFD was common in Africa. About 1,357 isolates were successfully sequenced of pfk13-propeller domain, the wild type was found in 1,308 samples (96.4%) whereby 49 samples (3.6%) had mutation in pfk13. Of 49 samples with pfk13 mutations, 22 non-synonymous and 4 synonymous polymorphic sites were confirmed. The A578S was the most common mutation in pfk13-propeller domain and three mutations associated with artemisinin resistance (M476I, R539T, P553L) were identified in three isolates. Conclusion This study provides evidence that could give insight into potential issues with anti-malarial drug resistance to inform national drug policy in China in order to treat imported cases.

Fluorinated metal−organic framework materials (NbOFFIVE-1-Ni, also referred to as KAUST-7) have attracted widespread attention because of their high chemical stability and thermal stability, outstanding tolerance with water and H 2 S, and high CO 2 -adsorption selectivity over H 2 and CH 4 . KAUST-7 was expected to be a new membrane material candidate for H 2 /CO 2 separation because of the hindered permeation of CO 2 resulting from the interaction between CO 2 and (NbOF 5 ) 2− of the KAUST-7 framework. A highly H 2 perm-selective KAUST-7 membrane was first achieved using a novel strategy of inorganic pillar centerfacilitated counterdiffusion (IPCFCD) proposed by us. The IPCFCD method not only effectively avoided the corrosion of hydrofluoric acid to α-Al 2 O 3 tubes in the process of preparing KAUST-7 membranes, but also better reduced grain boundary defects because of the faster nucleation rate and resultant high crystallinity. The KAUST-7 membrane exhibited a high H 2 /CO 2 separation factor (SF) of 27.30 for the 1:1 H 2 /CO 2 binary gas mixture with a high H 2 permeance of 5.30 × 10 −7 mol m −2 s −1 Pa −1 under ambient conditions and a slight decrease of the H 2 /CO 2 SF with increasing operation temperature and presence of steam. This study highlighted the importance of pre-synthesizing inorganic pillar centers (NiNbOF 5 intermediate) and the innovation of a membrane formation process for synthesizing polycrystalline KAUST-7 membranes. Most important of all, our study provided a novel approach to overcome the challenge in fabricating metal−organic framework membranes containing corrosive reactants for the corresponding supports.

Background China has reached important milestones in the elimination of malaria. However, the numbers of imported recurrent cases of Plasmodium vivax and P. ovale are gradually increasing, which increases the risk of malaria re-establishment in locations where Anopheles mosquitoes exist. The aim of this study is to characterize the epidemiological profiles of imported recurrent P. vivax and P. ovale cases, quantifying the recurrence burden and guiding the development of appropriate public health intervention strategies. Methods Individual-level data of imported recurrent P. vivax and P. ovale cases were collected from 2013 to 2020 in China via the Parasitic Diseases Information Reporting Management System. Demographic characteristics, temporal and spatial distributions, and the interval from previous infection to recurrence were analyzed by SAS, ArcGIS and GraphPad Prism software, respectively, to explore the epidemiological profiles of imported recurrent cases. Results A total of 307 imported recurrent cases, including 179 P. vivax and 128 P. ovale cases, were recorded. The majority of cases occurred in males (P. vivax 91.1%, P. ovale 93.8%) and migrant workers (P. vivax 43.2%, P. ovale 44.7%). Individuals aged 30–39 years had the highest P. vivax and P. ovale recurrent infection rates, respectively. The number of imported recurrent cases of infection by these two malaria species increased from 2013 to 2018, and P. vivax infection showed well-defined seasonality, with two peaks in February and June, respectively. More than 90% of patients with recurrent cases did not receive radical treatment for previous infection. Most imported recurrent P. vivax cases were reported in Yunnan Province and were imported from Myanmar, Ethiopia, and Pakistan, while most recurrent P. ovale cases were reported in southern China and primarily imported from Cameroon, Ghana, and Nigeria. The intervals from previous malaria infection to recurrence among different continents were significantly different (P = 0.0016) for P. vivax malaria but not for P. ovale malaria (P = 0.2373). Conclusions The large number of imported recurrent cases has been a major challenge in the prevention of malaria re-establishment in China. This study provides evidence to guide the development of appropriate public health intervention strategies for imported recurrent P. vivax and P. ovale cases. Graphic abstract

Malaria cases have dramatically declined in China along the Myanmar border, attributed mainly to adoption of the 1-3-7 surveillance and response approach. No indigenous cases have been reported in China since 2017. Counties in the middle and southern part of the border area have a higher risk for malaria importation and reestablishment after elimination.

Background Anti-malarial drug resistance is still a major threat to malaria elimination in the Great Mekong Sub-region. Plasmodium vivax parasites resistant to anti-malarial drugs are now found in Myanmar. Molecular surveillance on drug resistance genes in P. vivax parasites from northeastern Myanmar was aimed at estimating the underlying drug resistance in this region. Methods Blood samples from patients with vivax malaria were collected from Laiza city in northeastern Myanmar in 2020. Drug resistance genes including Pvcrt-o, Pvmdr1, Pvdhfr and Pvdhps were amplified and sequenced. Genetic polymorphisms and haplotypes were analysed to evaluate the prevalence of mutant alleles associated with drug resistance. Results A total of 149 blood samples from P. vivax patients were collected. The prevalence of Pvmdr1 mutations at codons 958 and 1076 was 100.0% and 52.0%, respectively, whereas no single nucleotide polymorphism was present at codon 976. The proportions of single and double mutant types were 48.0% and 52.0%, respectively. A K10 “AAG” insertion in the Pvcrt-o gene was not detected. Mutations in Pvdhfr at codons 57, 58, 61, 99 and 117 were detected in 29.9%, 54.3%, 27.6%, 44.9% and 55.1% of the samples, respectively. Wild type was predominant (46.3%), followed by quadruple and double mutant haplotypes. Of three types of tandem repeat variations of Pvdhfr, Type B, with three copies of GGDN repeats, was the most common. Pvdhps mutations were only detected at codons 383 and 553 and the wild type Pvdhps was dominant (78.0%). Eleven haplotypes were identified when combining the mutations of Pvdhfr and Pvdhps, among which the predominant one was the wild type (33.9%), followed by double mutant alleles S58R/S117N /WT (24.6%). Conclusions This study demonstrated resistant P. vivax phenotypes exists in northeastern Myanmar. Continued surveillance of drug resistance markers is needed to update treatment guidelines in this region.

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China was declared malaria free in June of 2021. In the post-elimination setting, vigilant surveillance is essential to sustain malaria free status. Serological surveillance has been recognized as an efficient tool for assessing the immunity levels and exposure risk in a population. In this study, a cross-sectional serological survey was conducted in Yingjiang County, China, in August–September, 2021. The study sites were villages along the borders with Myanmar, which have no local transmission since the last indigenous case registered in 2016. A total of 923 participants from six villages were enrolled. The majority was aged &gt; 36 years (56.12%) and 12.46% (115/923) participants had experienced malaria infection at least once. A magnetic- bead-based assay was used to test antibodies against Plasmodium vivax antigen PvMSP-119 to evaluate the prevalence of antibody positive subjects. A reversible catalytic model was used to assess the risk of exposure. The prevalence of anti-PvMSP-119 IgG was 12.84% [95% confidence interval (CI): 9.22%–16.47%], 13.93% (95% CI: 10.11%–17.74%), and 3.57% (95% CI: 1.40%–5.75%) in three different line-of-defense areas, which differed significantly (P &lt; 0.0001). The prevalence of anti-PvMSP-119 IgG increased with age and no statistically significant difference was detected between the sexes. The reversible catalytic model indicated that the seropositive conversion rate and seronegative reversion rate were 0.0042, 0.0034, 0.0032 and 0.0024, 0.0004, 0.0065 in the first-, second-line-of-defense area and total areas, respectively, and the fitted value did not differ significantly from the observed value (P &gt; 0.1). Although this study found the prevalence of antibody-positive subjects and the seroconversion rate in this post-elimination setting were lower than that in transmission setting, the population still had an exposure risk. Serological surveillance should be considered in post-elimination settings to provide valuable information with which to evaluate the risk of malaria re-establishment.

Background The emergence and spread of multidrug resistance pose a significant risk to malaria control and eradication goals in the world. There has been no indigenous malaria cases reported since 2017, and China is approaching malaria elimination by 2020. Therefore, it is urgent to monitor antimalarial drug resistance and track the emergence and spread of the imported drug resistant malaria cases in China. Methods Dried blood samples were obtained from P. falciparum infected cases who returned from Africa to China between 2012–2015 prior to antimalarial drug treatment. The known polymorphisms relating to drug resistance of pfcrt, pfmdr1 gene, and the propeller domain of the K13 gene were evaluated by nested PCR and sequencing. The GraphPad prism was used to plot the prevalence of each mutation. The chi-squared test and two-sided P value of < 0.05 were used to evaluate differences with statistical significance. Results A total of 731 P. falciparum isolates were successfully genotyped at the pfcrt locus. The wild type haplotype of C72V73M74N75K76 was the most prevalent genotype with the prevalence of 62.8% and 29.8% of the isolates showed the triple mutant haplotype C72V73I74E75T76. Total 434 P. falciparum isolates were successfully sequenced and pfmdr1 allelic variants were only observed in codons 86, 184, and 1246. Twelve haplotypes were identified and the prevalence of the wild type variant pfmdr1 N86Y184D1246 was 44.1%. The single mutant pfmdr1 in codons 86 and 184 was predominant but D1246Y was rare. The double mutant genotype Y86F184D1246 was common in Africa. A total of 1381 P. falciparum isolates from 33 African countries were sequenced of K13-propeller domain and 1357 were successfully sequenced. The prevalence of K13 mutations was 3.6% and 26 different mutant alleles including 22 nonsynonymous and four synonymous variants (C469C, R471R, G496G, and A627A) were observed. The A578S was the most common haplotype of K13. Three mutation associated with artimisinin resistance (M476I, R539T, and P553L) were observed in three isolates. Conclusion The prevalence of mutant pfcrt and pfmdr1 was low or moderate in P. falciparum isolates imported from Africa to China between 2012–2015. K13-propeller mutations were highly diverse but most mutations were only found in a few isolates. This study provides evidence for the antimalarial drug resistance level of the imported malaria cases from Africa and the efficacy of antimalarial drug policy in China to treat these imported cases.