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1.
Infect Dis Poverty ; 12(1): 101, 2023 Nov 20.
Article in English | MEDLINE | ID: mdl-37986018

ABSTRACT

BACKGROUND: Plasmodium malariae was always neglected compared with P. falciparum and P. vivax. In the present study, we aimed to describe the epidemiology of reported cases infected with P. malariae in the past decade to raise awareness of the potential threat of this malaria parasite in China. METHODS: Individual data of malaria cases infected with P. malariae reported in China in the past decade were collected via the China Information System for Disease Control and Prevention and Parasitic Diseases Information Reporting Management System, to explore their epidemiological characteristics. Pearson Chi-square tests or Fisher's Exact Test was used in the statistical analysis. RESULTS: From 2013 to 2022, a total of 581 P. malariae cases were reported in China, and mainly concentrated in 20-59 years old group (P < 0.001), and there was no significant trend in the number of cases reported per month. Moreover, four kinds of P. malariae cases were classified, including 567 imported cases from 41 countries in 8 regions and distributed in 27 provinces (autonomous regions, municipalities) in China, six indigenous cases in a small outbreak in Hainan, seven recurrent cases in Guangdong and Shanghai, and one induced case in Shanghai, respectively. In addition, only 379 cases (65.2%) were diagnosed as malaria on the first visit (P < 0.001), and 413 cases (71.1%) were further confirmed as P. malariae cases (P = 0.002). Meanwhile, most cases sought healthcare first in the health facilities at the county and prefectural levels, but only 76.7% (161/210) and 73.7% (146/198) cases were diagnosed as malaria, and the accuracy of confirmed diagnosis as malaria cases infected with P. malariae was only 77.2% (156/202) and 69.9% (167/239) in these health facilities respectively. CONCLUSIONS: Even though malaria cases infected with P. malariae didn't account for a high proportion of reported malaria cases nationwide, the threat posed by widely distributed imported cases, a small number of indigenous cases, recurrent cases and induced case cannot be ignored in China. Therefore, it is necessary to raise awareness and improve the surveillance and response to the non-falciparum species such as P. malariae, and prevent the reestablishment of malaria transmission after elimination.


Subject(s)
Malaria, Falciparum , Malaria, Vivax , Malaria , Humans , Young Adult , Adult , Middle Aged , Plasmodium malariae , China/epidemiology , Malaria/prevention & control
3.
Malar J ; 22(1): 152, 2023 May 09.
Article in English | MEDLINE | ID: mdl-37161379

ABSTRACT

There has been a significant reduction in malaria morbidity and mortality worldwide from 2000 to 2019. However, the incidence and mortality increased again in 2020 due to the disruption to services during the COVID-19 pandemic. Surveillance to reduce the burden of malaria, eliminate the disease and prevent its retransmission is, therefore, crucial. The 1-3-7 approach proposed by China has played an important role in eliminating malaria, which has been internationally popularized and adopted in some countries to help eliminate malaria. This review summarizes the experience and lessons of 1-3-7 approach in China and its application in other malaria-endemic countries, so as to provide references for its role in eliminating malaria and preventing retransmission. This approach needs to be tailored and adapted according to the region condition, considering the completion, timeliness and limitation of case-based reactive surveillance and response. It is very important to popularize malaria knowledge, train staff, improve the capacity of health centres and monitor high-risk groups to improve the performance in eliminating settings. After all, remaining vigilance in detecting malaria cases and optimizing surveillance and response systems are critical to achieving and sustaining malaria elimination.


Subject(s)
COVID-19 , Malaria , Humans , COVID-19/epidemiology , COVID-19/prevention & control , Pandemics/prevention & control , China/epidemiology , Health Facilities , Malaria/epidemiology , Malaria/prevention & control
4.
Travel Med Infect Dis ; 53: 102575, 2023.
Article in English | MEDLINE | ID: mdl-37100163

ABSTRACT

OBJECTIVE: No indigenous malaria cases have been reported since 2017 in China, but a large number of imported cases are still reported every year, including those from the land bordering countries. To characterize their epidemiological profiles will provide evidence for the development of appropriate strategies to effectively address the challenges of border malaria in the post-elimination phase. METHODS: Individual-level data of imported malaria cases from the land bordering countries were collected from 2017 to 2021 in China via the web-based surveillance systems, and analyzed by SPSS, ArcGIS and WPS software, to explore their epidemiological profiles. RESULTS: A total of 1170 malaria cases imported into China from six of the fourteen land bordering countries were reported between 2017 and 2021 with a decline trend. Overall, cases were widely distributed in 31-97 counties from 11 to 21 provinces but mainly in Yunnan. Moreover, these imported cases were mainly infected with P. vivax (94.8%), and a total of 68 recurrent cases were reported in 6-14 counties from 4 to 8 provinces. In addition, nearly 57.1% of the total reported cases could seek healthcare within 2 days of getting sick, and 71.3% of the reported cases could be confirmed as malaria on the day they sought medical care. CONCLUSIONS: China still needs to attach great importance to the risk and challenge of the imported malaria from bordering countries particularly from Myanmar in preventing reestablishment of malaria transmission in the post-elimination phase. It is necessary not only to strengthen collaboration and cooperation with the bordering countries, but also coordinate multiple departments at home to improve malaria surveillance and response system and prevent the reestablishment of malaria transmission in China.


Subject(s)
Malaria, Vivax , Malaria , Humans , China/epidemiology , Malaria/epidemiology , Malaria/prevention & control , Malaria, Vivax/epidemiology , Myanmar
5.
Front Med ; 17(1): 85-92, 2023 Feb.
Article in English | MEDLINE | ID: mdl-36469233

ABSTRACT

In 2017, China achieved the target of zero indigenous malaria case for the first time, and has been certified as malaria free by World Health Organization in 2021. To further summarize the historical achievements and technical experiences of the elimination program, a project on the Roadmap Analysis and Verification for Malaria Elimination in China was carried out. Results of the project were compiled and published as the Atlas of Malaria Transmission in China (The Atlas). The Atlas using modern digital information technologies, has been supported by various data from 24 malaria endemic provinces of China since 1950, to assess the changes in malaria epidemic patterns from 1950 to 2019 at national and provincial levels. The Atlas is designed as two volumes, including a total of 1850 thematic maps and more than 130 charts, consisting of introductory maps, thematic maps of malaria epidemic and control at national and provincial levels. It objectively and directly shows the epidemic history, evolution process, and great achievements of the national malaria control and elimination program in China. The Atlas has important reference value for summing up historical experience in the national malaria elimination program of China, and malaria control and elimination in other endemic countries in the world.


Subject(s)
Malaria , Humans , Malaria/epidemiology , Malaria/prevention & control , China/epidemiology
6.
Malar J ; 21(1): 369, 2022 Dec 04.
Article in English | MEDLINE | ID: mdl-36464686

ABSTRACT

BACKGROUND: Artemisinin-based combination therapy (ACT) has been recommended as the first-line treatment by the World Health Organization to treat uncomplicated Plasmodium falciparum malaria. However, the emergence and spread of P. falciparum resistant to artemisinins and their partner drugs is a significant risk for the global effort to reduce disease burden facing the world. Currently, dihydroartemisinin-piperaquine (DHA-PPQ) is the most common drug used to treat P. falciparum, but little evidence about the resistance status targeting DHA (ACT drug) and its partner drug (PPQ) has been reported in Shandong Province, China. METHODS: A retrospective study was conducted to explore the prevalence and spatial distribution of Pfk13 and Pfcrt polymorphisms (sites of 72-76, and 93-356) among imported P. falciparum isolates between years 2015-2019 in Shandong Province in eastern China. Individual epidemiological information was collected from a web-based reporting system were reviewed and analysed. RESULTS: A total of 425 P. falciparum blood samples in 2015-2019 were included and 7.3% (31/425) carried Pfk13 mutations. Out of the isolates that carried Pfk13 mutations, 54.8% (17/31) were nonsynonymous polymorphisms. The mutant alleles A578S, Q613H, C469C, and S549S in Pfk13 were the more frequently detected allele, the mutation rate was the same as 9.7% (3/31). Another allele Pfk13 C580Y, closely associated with artemisinin (ART) resistance, was found as 3.2% (2/31), which was found in Cambodia. A total of 14 mutant isolates were identified in Western Africa countries (45.2%, 14/31). For the Pfcrt gene, the mutation rate was 18.1% (77/425). T76T356 and T76 were more frequent in all 13 different haplotypes with 26.0% (20/77) and 23.4% (18/77). The CVIET and CVIKT mutant at loci 72-76 have exhibited a prevalence of 19.5% (15/77) and 3.9% (3/77), respectively. The CVIET was mainly observed in samples from Congo (26.7%, 4/15) and Mozambique (26.7%, 4/15). No mutations were found at loci 97, 101 and 145. For polymorphisms at locus 356, a total of 24 isolates were identified and mainly from Congo (29.2%, 7/24). CONCLUSION: These findings indicate a low prevalence of Pfk13 in the African isolates. However, the emergence and increase in the new alleles Pfcrt I356T, reveals a potential risk of drug pressure in PPQ among migrant workers returned from Africa. Therefore, continuous molecular surveillance of Pfcrt mutations and in vitro susceptibility tests related to PPQ are necessary.


Subject(s)
Artemisinins , Malaria, Falciparum , Humans , Plasmodium falciparum/genetics , Retrospective Studies , Artemisinins/pharmacology , Malaria, Falciparum/epidemiology , China/epidemiology
7.
Can J Infect Dis Med Microbiol ; 2022: 8003845, 2022.
Article in English | MEDLINE | ID: mdl-36349187

ABSTRACT

Introduction: Qualified microscopy competency is a key indicator for certification of malaria elimination. To better prepare the country certification and identify the priorities that need improvement to prevent malaria reestablishment, microscopy competency at different levels were assessed in subnational verification of malaria elimination in China. Methodology. Microscopist representatives from centers for disease control and prevention (CDC)/institutes of parasitic diseases (IPD) and medical institutes for malaria diagnosis at the provincial and county levels in the subnational verification were analyzed. Specifically, five provincial microscopist representatives and ten county-level representatives were assessed in each of previously endemic provinces on qualitative identification (Plasmodium positive or negative) and Plasmodium species identification using standard slides from the National Malaria Diagnosis Reference Laboratory. Results: A total of 100 provincial-level representatives (60 from 42 CDCs/IPDs and 40 from 34 medical institutes) and 200 county-level representatives (61 from 41 CDCs and 139 from 118 medical institutes) were included. The qualitative accuracy was higher than 90% each (P = 0.137), but slides with low parasite density were easy to be misdiagnosed as negative. Furthermore, the accuracy of species identification was 80.0% and 83.6% in medical institutes and centers for disease control and prevention (CDCs) at the provincial level (P = 0.407) with relatively high misdiagnosis of P. vivax as P. ovale in the latter (16.2%) and 82.0% and 85.0% in medical institutes and CDCs at the county level (P = 0.330) for the identification of P. falciparum and non-P. falciparum with higher false-negative in medical institutions (P < 0.001). Conclusions: In conclusion, competent microscopy in subnational verification supported the quality in eliminating malaria in China, while the accurate identification of malaria parasites, especially slides with low parasite density still need to be improved through continuous diagnostic platform construction, continuous technological innovation, and targeted training to prevent reestablishment of malaria transmission.

8.
Front Med ; 16(1): 83-92, 2022 Feb.
Article in English | MEDLINE | ID: mdl-35257293

ABSTRACT

The dihydrofolate reductase (dhfr) and dihydropteroate synthetase (dhps) genes of Plasmodium vivax, as antifolate resistance-associated genes were used for drug resistance surveillance. A total of 375 P. vivax isolates collected from different geographical locations in China in 2009-2019 were used to sequence Pvdhfr and Pvdhps. The majority of the isolates harbored a mutant type allele for Pvdhfr (94.5%) and Pvdhps (68.2%). The most predominant point mutations were S117T/N (77.7%) in Pvdhfr and A383G (66.8%) in Pvdhps. Amino acid changes were identified at nine residues in Pvdhfr. A quadruple-mutant haplotype at 57, 58, 61, and 117 was the most frequent (57.4%) among 16 distinct Pvdhfr haplotypes. Mutations in Pvdhps were detected at six codons, and the double-mutant A383G/A553G was the most prevalent (39.3%). Pvdhfr exhibited a higher mutation prevalence and greater diversity than Pvdhps in China. Most isolates from Yunnan carried multiple mutant haplotypes, while the majority of samples from temperate regions and Hainan Island harbored the wild type or single mutant type. This study indicated that the antifolate resistance levels of P. vivax parasites were different across China and molecular markers could be used to rapidly monitor drug resistance. Results provided evidence for updating national drug policy and treatment guidelines.


Subject(s)
Antimalarials , Folic Acid Antagonists , Antimalarials/pharmacology , China/epidemiology , Drug Combinations , Drug Resistance/genetics , Folic Acid Antagonists/pharmacology , Humans , Mutation , Plasmodium vivax/genetics , Prevalence
9.
Front Med ; 16(1): 10-16, 2022 Feb.
Article in English | MEDLINE | ID: mdl-35226298

ABSTRACT

Malaria remains a global health challenge, although an increasing number of countries will enter pre-elimination and elimination stages. The prompt and precise diagnosis of symptomatic and asymptomatic carriers of Plasmodium parasites is the key aspect of malaria elimination. Since the launch of the China Malaria Elimination Action Plan in 2010, China has formulated clear goals for malaria diagnosis and has established a network of malaria diagnostic laboratories within medical and health institutions at all levels. Various external quality assessments were implemented, and a national malaria diagnosis reference laboratory network was established to strengthen the quality assurance in malaria diagnosis. Notably, no indigenous malaria cases have been reported since 2017, but the risk of re-establishment of malaria transmission cannot be ignored. This review summarizes the lessons about malaria diagnosis in the elimination phase, primarily including the establishments of laboratory networks and quality control in China, to better improve malaria diagnosis and maintain a malaria-free status. A reference is also provided for countries experiencing malaria elimination.


Subject(s)
Malaria , China/epidemiology , Clinical Laboratory Techniques , Global Health , Humans , Laboratories , Malaria/diagnosis , Malaria/epidemiology , Malaria/prevention & control
10.
Emerg Microbes Infect ; 11(1): 314-325, 2022 Dec.
Article in English | MEDLINE | ID: mdl-34989665

ABSTRACT

ABSTRACTOn 30 June 2021, China was certified malaria-free by the World Health Organization. In this study, the evolution, performance, outcomes, and impact of China's adaptive strategy and approach for malaria elimination from 2011 to 2020 were analysed using 10-year data. The strategy and approach focused on timely detection and rapid responses to individual cases and foci. Indigenous cases declined from 1,308 in 2011 to 36 in 2015, and the last one was reported from Yunnan Province in April 2016, although thousands of imported cases still occur annually. The "1-3-7" approach was implemented successfully between 2013 and 2020, with 100% of cases reported within 24 h, 94.5% of cases investigated within three days of case reporting, and 93.4% of foci responses performed within seven days. Additionally, 81.6% of patients attended the first healthcare visit within 1-3 days of onset and 58.4% were diagnosed as malaria within three days of onset, in 2017-2020. The adaptive strategy and approach, along with their universal implementation, are most critical in malaria elimination. In addition to strengthening surveillance on drug resistance and vectors and border malaria collaboration, a further adapted three-step strategy and the corresponding "3-3-7" model are recommended to address the risks of re-transmission and death by imported cases after elimination. China's successful practice and lessons learnt through long-term efforts provide a reference for countries moving towards elimination.


Subject(s)
Malaria , China/epidemiology , Humans , Malaria/epidemiology , Malaria/prevention & control , World Health Organization
11.
Emerg Infect Dis ; 27(11): 2869-2873, 2021 11.
Article in English | MEDLINE | ID: mdl-34670652

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.


Subject(s)
Malaria , China/epidemiology , Humans , Malaria/epidemiology , Malaria/prevention & control , Myanmar/epidemiology
12.
China CDC Wkly ; 3(17): 360-365, 2021 Apr 23.
Article in English | MEDLINE | ID: mdl-34594884
13.
China CDC Wkly ; 3(17): 366-371, 2021 Apr 23.
Article in English | MEDLINE | ID: mdl-34594885
14.
Front Cell Infect Microbiol ; 11: 673194, 2021.
Article in English | MEDLINE | ID: mdl-34568082

ABSTRACT

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.


Subject(s)
Antimalarials , Malaria, Falciparum , Africa , Antimalarials/pharmacology , China , Cross-Sectional Studies , Drug Combinations , Drug Resistance/genetics , Humans , Mutation , Plasmodium falciparum/genetics , Protozoan Proteins/genetics , Pyrimethamine , Sulfadoxine , Tetrahydrofolate Dehydrogenase/genetics
15.
Front Cell Infect Microbiol ; 11: 666469, 2021.
Article in English | MEDLINE | ID: mdl-34490134

ABSTRACT

Vector control interventions including long-lasting insecticidal nets and indoor residual spraying are important for malaria control and elimination. And effectiveness of these interventions depends entirely on the high level of susceptibility of malaria vectors to insecticides. However, the insecticide resistance in majority of mosquito vector species across African countries is a serious threat to the success of vector control efforts with the extensive use of insecticides, while no data on insecticide resistance was reported from Sierra Leone in the past decade. In the present study, the polymerase chain reaction was applied for the identification of species of 757 dry adult female Anopheles gambiae mosquitoes reared from larvae collected from four districts in Sierra Leone during May and June 2018. And the mutations of kdr, rdl, ace-1 genes in An. gambiae were detected using SNaPshot and sequencing. As a result, one sample from Western Area Rural district belonged to Anopheles melas, and 748 An. gambiae were identified. Furthermore, the rdl mutations, kdr west mutations and ace-1 mutation were found. The overall frequency was 35.7%, 0.3%, 97.6% and 4.5% in A296G rdl, A296S rdl, kdrW and ace-1, respectively. The frequencies of A296G rdl mutation (P < 0.001), kdrW mutation (P = 0.001) and ace-1 mutation (P < 0.001) were unevenly distributed in four districts, respectively, while no statistical significance was found in A296S rdl mutation (P = 0.868). In addition, multiple resistance patterns were also found. In conclusion, multiple mutations involved in insecticide resistance in An. gambiae populations in Sierra Leone were detected in the kdrW, A296G rdl and ace-1 alleles in the present study. It is necessary to monitor vector susceptibility levels to insecticides used in this country, and update the insecticide resistance monitoring and management strategy.


Subject(s)
Anopheles , Insecticides , Animals , Anopheles/genetics , Female , Insecticide Resistance/genetics , Insecticides/pharmacology , Mutation , Sierra Leone
16.
Sci Rep ; 11(1): 14129, 2021 07 08.
Article in English | MEDLINE | ID: mdl-34239003

ABSTRACT

Yingjiang County, which is on the China-Myanmar border, is the main focus for malaria elimination in China. The epidemiological characteristics of malaria in Yingjiang County were analysed in a retrospective analysis. A total of 895 malaria cases were reported in Yingjiang County between 2013 and 2019. The majority of cases occurred in males (70.7%) and individuals aged 19-59 years (77.3%). Plasmodium vivax was the predominant species (96.6%). The number of indigenous cases decreased gradually and since 2017, no indigenous cases have been reported. Malaria cases were mainly distributed in the southern and southwestern areas of the county; 55.6% of the indigenous cases were reported in Nabang Township, which also had the highest risk of imported malaria. The "1-3-7" approach has been implemented effectively, with 100% of cases reported within 24 h, 88.9% cases investigated and confirmed within 3 days and 98.5% of foci responded to within 7 days. Although malaria elimination has been achieved in Yingjiang County, sustaining elimination and preventing the re-establishment of malaria require the continued strengthening of case detection, surveillance and response systems targeting the migrant population in border areas.


Subject(s)
Malaria, Falciparum/epidemiology , Malaria, Vivax/epidemiology , Plasmodium falciparum/pathogenicity , Plasmodium vivax/pathogenicity , Adult , China/epidemiology , Epidemiologic Studies , Female , Humans , Malaria, Falciparum/parasitology , Malaria, Vivax/parasitology , Male , Middle Aged , Myanmar/epidemiology , Transients and Migrants , Young Adult
17.
Infect Dis Poverty ; 10(1): 80, 2021 Jun 01.
Article in English | MEDLINE | ID: mdl-34074332

ABSTRACT

BACKGROUND: Chinese Center for Disease Control and Prevention (China CDC) introduced the Structured Operational Research Training Initiative (SORT IT) into China to build a special capacity and equip public health professionals with an effective tool to support developing countries in strengthening their operational research. The paper aims to investigate and analyze the implementation, outcomes and challenges of the first cycle of SORT IT in China. MAIN TEXT: As a result of the successful implementation, SORT IT China, Cycle 1 has demonstrated fruitful outputs as exemplified by the 18-month follow-up to the post-training initiatives of the twelve participants, who all achieved the four milestones required by SORT IT. Eleven of twelve (92%) manuscripts generated that focused on the prevention and control of malaria, influenza, HIV/AIDS, hepatitis B, schistosomiasis, tuberculosis and Japanese encephalitis were published by peer-reviewed international journals with the impact factor ranging from 2.6 to 4.8. The most up-to-date citation count on February 19, 2021 was 53 times out of which 31 times were cited by Science Citation Index papers with 94.827 impact factor in total. Six senior professionals from China CDC also facilitated the whole SORT IT training scheme as co-mentors under the guidance of SORT IT mentors. The twelve participants who gained familiarity with the SORT IT courses and training principles are likely become potential mentors for future SORT IT, but they as the non-first language speakers/users of English also faced the challenge in thoroughly understanding the modules delivered in English and writing English academically to draft the manuscripts. CONCLUSION: The outcomes from the first cycle of SORT IT in China have led to studies contributing to narrowing the knowledge gap among numerous public health challenges nationally and internationally. It is believed the researchers who participated will continue to apply the skills learned within their domain and help build the training capacity for future operational research courses both in China and in developing countries with similar needs.


Subject(s)
Capacity Building , Operations Research , China , Humans , Public Health , Research Personnel
18.
Infect Genet Evol ; 92: 104852, 2021 08.
Article in English | MEDLINE | ID: mdl-33831542

ABSTRACT

The resistance of mosquito vectors to insecticides is one of the biological obstacles in the fight against malaria. Understanding of the status and mechanisms underlying the insecticide resistance in Anopheles gambiae species is necessary for success of vector control efforts. The study aimed to determine the molecular forms of An. gambiae from four districts in Sierra Leone during May and June 2018, and the level of N1575Y mutation. The molecular form identification of adult female An. gambiae mosquitoes reared from larvae were carried out using polymerase chain reaction and sequencing. And the N1575Y mutations were detected using SNaPshot and sequencing. As a result, significant differences were found in the distribution of An. gambiae molecular forms among regions (P < 0.001). And a total of 638 An. gambiae sensu stricto, 106 An. coluzzi, and 4 hybrid individuals were identified. Moreover, the overall N1575Y mutation frequency was 10.2% with no statistical difference among regions (χ2 = 3.009, P = 0.390). In addition, no significant differences in N1575Y mutation frequency were found among different An. gambiae molecular forms (P = 0.383). In conclusion, the N1575Y mutation in An. gambiae populations in Sierra Leone was reported for the first time in the present study. It provides key evidence for the necessity of monitoring vector susceptibility levels to insecticides used in this country.


Subject(s)
Anopheles/genetics , Mutation/genetics , Animals , Anopheles/drug effects , Female , Insecticide Resistance/genetics , Insecticides/pharmacology , Larva/genetics , Malaria/diet therapy , Malaria/parasitology , Mosquito Vectors/genetics , Mutation Rate , Sierra Leone
19.
Malar J ; 20(1): 73, 2021 Feb 06.
Article in English | MEDLINE | ID: mdl-33549122

ABSTRACT

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.


Subject(s)
Plasmodium falciparum/genetics , Protozoan Proteins/analysis , Africa , China , Epidemiological Monitoring , Membrane Transport Proteins/analysis , Multidrug Resistance-Associated Proteins/analysis
20.
Infect Dis Poverty ; 9(1): 158, 2020 Nov 19.
Article in English | MEDLINE | ID: mdl-33213516

ABSTRACT

BACKGROUND: Malaria cases have declined significantly along the China-Myanmar border in the past 10 years and this region is going through a process from control to elimination. The aim of this study is to investigate the epidemiology of malaria along the border, will identify challenges in the progress from control to elimination. METHODS: National reported malaria cases from China and Myanmar, along with the data of 18 Chinese border counties and 23 townships in Myanmar were obtained from a web-based diseases information reporting system in China and the national malaria control program of Myanmar, respectively. Epidemiological data was analyzed, including the number of reported cases, annual parasite index and proportion of vivax infection. Spatial mapping of the annual parasite index (API) at county or township level in 2014 and 2018 was performed by ArcGIS. The relationship of malaria endemicity on both sides of the border was evaluated by regression analysis. RESULTS: The number of reported malaria cases and API declined in the border counties or townships. In 2014, 392 malaria cases were reported from 18 Chinese border counties, including 8.4% indigenous cases and 91.6% imported cases, while the highest API (0.11) was occurred in Yingjiang County. There have been no indigenous cases reported since 2017, but 164 imported cases were reported in 2018 and 97.6% were imported from Myanmar. The average API in 2014 in 23 Myanmar townships was significantly greater than that of 18 Chinese counties (P < 0.01). However, the API decreased significantly in Myanmar side from 2014 to 2018 (P < 0.01). The number of townships with an API between 0 and 1 increased to 15 in 2018, compared to only five in 2014, while still four townships had API > 10. Plasmodium vivax was the predominant species along the border. The number of reported malaria cases and the proportion of vivax infection in the 18 Chinese counties were strongly correlated with those of the 23 Myanmar townships (P < 0.05). CONCLUSIONS: Malaria elimination is approaching along the China-Myanmar border. However, in order to achieve the malaria elimination in this region and prevent the re-establishment of malaria in China after elimination, continued political, financial and scientific commitment is required.


Subject(s)
Malaria/epidemiology , Malaria/prevention & control , China/epidemiology , Disease Eradication , Humans , Malaria, Falciparum/epidemiology , Malaria, Vivax/epidemiology , Myanmar/epidemiology , Plasmodium falciparum/isolation & purification , Plasmodium vivax/isolation & purification , Regression Analysis , Seasons , Spatio-Temporal Analysis
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