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BackgroundSulfadoxine-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.MethodsIn 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.ResultsHigh 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).ConclusionA 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 Background During the past six decades, remarkable success on malaria control has been made in China. The major experience could be shared with other malaria endemic countries including Tanzania with high malaria burden. Especially, China’s 1–3-7 model for malaria elimination is one of the most important refined experiences from many years’ efforts and key innovation measures for malaria elimination in China. Methods The China-UK-Tanzania pilot project on malaria control was implemented from April, 2015 to June, 2018, which was an operational research with two communities receiving the proposed interventions and two comparable communities serving as control sites. The World Health Organization “Test, Treat, Track” (WHO-T3) Initiative, which calls for every suspected case to receive a diagnostic test, every confirmed case to be treated, and for the disease to be tracked, was integrated with Chinese experiences on malaria control and elimination for exploration of a proper model tailored to the local settings. Application of China’s 1–3-7 model integrating with WHO-T3 initiative and local resources aiming at reducing the burden of malaria in terms of morbidity and mortality by 30% in the intervention communities in comparison with that at the baseline survey. Discussion The China-UK-Tanzania pilot project on malaria control was that at China's first pilot project on malaria control in Africa, exploring the feasibility of Chinese experiences by China-Africa collaboration, which is expected that the strategies and approaches used in this project could be potential for scaling up in Tanzania and African countries, and contribute to the acceleration of malaria control and elimination in Africa.

Objective: To analyze the epidemic situation of malaria and explore the targeted control strategy in Guangxi from 2011 to 2018., Methods: The malaria surveillance data were collected in Guangxi Zhuang Autonomous Region from 2011 to 2018, and a descriptive method was employed to analyze the epidemiological features of the malaria cases., Results: A total of 2 944 malaria cases were reported in Guangxi Zhuang Autonomous Region from 2011 to 2018, including a case with local infection (0.03%) and 2 943 imported cases (99.97%). There were 2 933 cases (99.63%) positive for Plasmodium confirmed by laboratory testing, including 2 166 cases (73.86%) with P. falciparum malaria, 388 cases (13.23%) with P. ovale malaria, 276 cases (9.41%) with P. vivax malaria, 40 cases (1.36%) with P. malariae malaria and 62 cases (2.11%) with mixed infections, and 11 clinically diagnosed cases (0.37%). The malaria cases were distributed in 91 counties (districts) of 14 cities in Guangxi, with the largest number of cases found in Nanning City (2 515 cases, 85.43%). The malaria cases were originated from 29 countries in Africa (94.67%), 7 countries in Southeast Asia (5.10%), one country in South America (0.07%), 2 countries in South Asia and China (0.10%). In African countries, most malaria cases were from Ghana (1 947 cases, 66.13%), and in Southeast Asian countries, most cases were from Myanmar (75 cases, 2.55%). Most malaria cases were young men, and 2 899 cases (98.13%) were male, while 2 583 cases (87.74%) were at ages of 20 to 49 years. Gold washing and mining was the predominant occupation (2 561 cases, 86.99%), and the malaria cases were reported in each month across the year, with the largest number of cases detected in June (665 cases, 22.59%), while no season-specific distribution was found. There were 1 431 cases (48.61%) reported by disease control and prevention institutions, 1 511 cases (51.30%) reported by medical institutions, and 2 cases (0.07%) reported by inspection and quarantine institutions. During the period from 2011 to 2018, there were 6 deaths of imported malaria cases in Guangxi, and no secondary cases were reported., Conclusions: The epidemic situation of local malaria has been effectively controlled in Guangxi; however, there is a great challenge for the management of overseas imported malaria. Strengthening the monitoring and management of migrant labors is the key to consolidate the achievements of malaria elimination.

Objective: To analyze the epidemic characteristics of the imported malaria cases in Guangxi Zhuang Autonomous Region in 2014, so as to assess the transmission risk and explore the prevention and control strategy., Methods: The data of the malaria epidemic situation in the network direct report system of Guangxi in 2014 and the annual report of malaria epidemic situation in 14 cities were collected. The epidemiological information of the imported malaria cases was analyzed., Results: A total of 184 malaria patients were reported in Guangxi in 2014, with a descent rate of 85.29% when compared to that in 2013 (1 251 cases), and the incidence rate was 0.35/100 000. All the cases were imported from abroad, and four species of Plasmodium were found in their blood samples. The number of falciparum malaria cases was the most (49.46%), followed by the ovale malaria cases (32.07%). All the cases were distributed in 32 counties (districts) of 11 cities, and 65.76% of them were distributed in Shanglin County. Most of the cases were male (98.37%), and those aged in 20-49 years accounted for 87.50%. The imported cases came from 14 countries of Africa (86.41%) and 2 countries of Southeast Asia (13.59%), in which, 48.37% of the cases were imported from Garner. The main occupation of the cases in abroad was gold mining work (86.96%). The cases were reported all the year around, with no obvious seasonality. The interval time of back home to attack of the patients with tertian malaria and ovale malaria was longer., Conclusions: Africa and Southeast Asia is the main source of imported malaria cases in Guangxi, and the migrant workers returning home may have the risk of malaria recurrence, which should be paid enough attention to.

Objective: To review and investigate the malaria control history of Wuzhou City, Guangxi Zhuang Autonomous Region from 1950 to 2015, so as to provide the evidence for future malaria control and surveillance., Methods: The data of malaria control in Wuzhou City from 1950 to 2015 were collected and analyzed., Results: In 1950 decade, the malaria incidence in Wuzhou City was 1 435.55/100 000, higher than the average level in Guangxi, and the mortality of malaria was 0.95/100 000. The malaria incidence of local residents was reduced to 3.61/100 000 in 1979 and no local malaria case was found since. The imported malaria cases were found in Wuzhou City since 1980, and were more than local cases since 1981. In recent five years, 87.50% (7/8) of imported malaria cases were from south-east Asia., Conclusions: Wuzhou City has reached the national criterion of malaria elimination, but the imported malaria is the recent threat. The surveillance and control work of malaria should be strengthened.

Objective: To analyze the epidemiological characteristics of malaria in Hechi City, Guangxi Zhuang Autonomous Region from 2005 to 2015, so as to provide the evidence for formulating and adjusting measures of malaria elimination., Methods: The data of malaria cases in 11 counties of Hechi City from 2005 to 2015 were collected and analyzed by using Micro-soft Office Excel 2003 and SPSS 17.0., Results: A total of 160 malaria cases were reported in Hechi City from 2005 to 2015, and the annual average malaria incidence was 3.6 per million. There were 10 local recurrence cases (accounting for 6.25％, 10/160) and 150 imported cases (accounting for 93.75％, 150/160). For the etiology, Plasmodium vivax accounted for 51.87% (83/160) in these cases, P. falciparum accounted for 34.38% (55/160), P. ovale accounted for 1.25% (2/160), P. malariae accounted for 5.00% (8/160), and the indeterminate accounted for 7.50% (12/160). During the period of 11 years, the malaria incidence first dropped and then rose. There were no local cases after 2009. However, an imported falciparum malaria death case was reported in 2010, a severe imported falciparum malaria case was reported in 2013 and another in 2015. A severe case of maternal-neonatal vivax malaria was reported in 2014. These cases were mainly distributed in 10 counties of Hechi City, with more young male adults who engaged in digging mining. More cases concentrated from April to August. Most of the reported malaria cases were imported, 60.00% (96/160) of them returned from Africa and Southeast Asia, and 33.75% (54/160) from other domestic provinces. The median of the interval from symptom appearance to diagnosis was 5 d, and there was a significant difference among the above years (χ 2 = 33.40, P ＜0.05)., Conclusions: Malaria is still an important public health problem in Hechi City, and the appropriate control measures and effective tools should be strengthened for malaria elimination. The key to consolidate the achievements of malaria control is strengthening the malaria monitoring management of the floating population.

Objective: To analyze the data of epidemic situation of malaria in Longlin Various Nationalities Autonomous County, Guangxi Zhuang Autonomous Region, China from 1951 to 2014 and discuss the distribution characteristics and epidemic law, so as to provide the evidences for developing the prevention and control strategies of the disease., Methods: The data about the epidemic situation of malaria in Longlin Various Nationalities Autonomous County were collected and analyzed statistically with Excel 2007., Results: Totally 93 460 malaria cases were reported from 1951 to 2014 in the county. There were two morbidity peaks of malaria during this period, namely 1950s and 1970s, and the annual average incidence rates were 3 237.94/100 000 and 1 572.12/100 000, respectively, but it began to flatten after 1980s. Before 2000, the local cases were the main type, however, there were no endogenous cases since 2008. In 1950s, falciparum malaria was the main type of the disease, and the cases with falciparum malaria, tertian malaria and quartan malaria were accounted for 45.01% (2 392/5 314), 33.72% (1 792/5 314) and 19.55% (1 039/5 314), respectively; while in 1960s, the proportion of cases with tertian malaria increased, that of the cases with quartan malaria decreased, and there were no quartan malaria cases reported since 1980s. There were imported malaria cases reported since 1990s, and a total of 51 cases were found in this period, among which, 50 cases (98.04%) were tertian malaria, and the main infection sources were the cases from epidemic areas in other provinces of China. After 2000, the imported malaria cases with falciparum malaria increased, with a proportion of 60.00% (21/35), and the infection sources were mainly from Africa and Southeast Asia., Conclusions: The local endemic of malaria in Longlin Various Nationalities Autonomous County has been effectively controlled, but the situation of imported malaria is still severe in this county. Therefore, strengthening the surveillance of floating population, especially the workers backing from overseas, is still the key of malaria prevention and control in the future.