Risk factors for clonorchiasis: a Meta-analysis / 中国热带医学

@#Abstract: Objective　Quantitative assessment of risk factors of clonorchiasis can provide prevention for clonorchiasis. Methods　Articles were retrieved in Chinese and English electronic databases from January 1, 2000 to December 31, 2020, including Wanfang Data, CNKI, PubMed, Web of Science, Embase. All studies were screened based on inclusion and exclusion criteria, and the quality of all enrolled literatures was evaluated. The software RevMan version 5.3 was used for Meta-analysis. The heterogeneity, sensitivity and publication bias of all included studies were analyzed. Results　A total of 95 articles were retrieved, and 6 were included in this Meta-analysis which were case-control studies. There were 5 articles in Chinese and 1 in English. There was no single literature with a large impact on the results, and the results of this study were relatively stable. There were 1 170 cases of clonorchiasis in total and 1 291 cases in control. Most of the cases were from hospital patients and community residents, and the floating population was small. Meta-analysis showed that there were three independent risk factors: raw or semi-raw fish, raw or semi-raw shrimp, mix raw and cooked cutting boards, with a combined OR (95%CI) of 2.32(1.86, 2.88), 3.99(2.42, 6.58), 2.18(1.51, 3.14), respectively, with low heterogeneity consistent with the results of the total sample study: I2 values for risk factors were 30%, 12%, 27%, respectively. The results of bias tests showed no publication bias (P=0.731, 0.725, 0.334, P>0.05). Conclusions　The key risk factors of clonorchiasis are raw or semi-raw fish, raw or semi-raw shrimp, mix raw and cooked cutting boards. Guidance and health education should be strengthened. It is necessary to strengthen the surveillance of clonorchiasis in the floating population, such as traveler, businessman and student.

Genetic Diversity Analysis of Surface-Related Antigen (SRA) in Plasmodium falciparum Imported From Africa to China.

Plasmodium falciparum surface-related antigen (SRA) is located on the surfaces of gametocyte and merozoite and has the structural and functional characteristics of potential targets for multistage vaccine development. However, little information is available regarding the genetic polymorphism of pfsra. To determine the extent of genetic variation about P. falciparum by characterizing the sra sequence, 74 P. falciparum samples were collected from migrant workers who returned to China from 12 countries of Africa between 2015 and 2019. The full length of the sra gene was amplified and sequenced. The average pairwise nucleotide diversities (π) of P. falciparum sra gene was 0.00132, and the haplotype diversity (Hd) was 0.770. The average number of nucleotide differences (k) for pfsra was 3.049. The ratio of non-synonymous (dN) to synonymous (dS) substitutions across sites (dN/dS) was 1.365. Amino acid substitutions of P. falciparum SRA could be categorized into 35 unique amino acid variants. Neutrality tests showed that the polymorphism of PfSRA was maintained by positive diversifying selection, which indicated its role as a potential target of protective immune responses and a vaccine candidate. Overall, the ability of the N-terminal of PfSRA antibodies to evoke inhibition of merozoite invasion of erythrocytes and conserved amino acid at low genetic diversity suggest that the N-terminal of PfSRA could be evaluated as a vaccine candidate against P. falciparum infection.

Classification of induced malaria case in an elimination setting: investigation of transfusion-transmitted malaria cases.

BACKGROUND: Since the National Malaria Elimination Action Plan was launched in China in 2010, local malaria transmission has decreased rapidly. Zero indigenous cases were reported since 2017. However, after 2010, the proportion of imported cases in China increased from 45.7% in 2010 to 99.9% in 2016, and almost all provinces of China have reported imported cases in recent years. Prevention of the reintroduction of malaria into China is crucial for the maintenance of its malaria-free status. Hence, it is of utmost importance to correctly identify the source of malaria infections within the country. CASE INTRODUCTION AND RESPONSE: In 2016 and 2017, three laboratory-confirmed cases of malaria caused by Plasmodium falciparum were identified in patients with no previous travel history to endemic areas were reported in Jiangsu Province, China, where malaria due to P. falciparum was eliminated about 30 years ago. These were diagnosed after 41, 31 and 39 days of seeking treatment, respectively, and all of them had received blood transfusions. Further investigations indicated that two of the cases had received blood from foreign students (from Indonesia and Ghana), and the other had received blood from an individual who had worked in Equatorial Guinea. All three blood donors were traced, and found to be carrying asymptomatic P. falciparum infections by microscopic examination and PCR. Furthermore, five polymorphic microsatellite markers (C1M4, C4M62, C13M13, C14M17, and C13M63) were typed and used to link parasites from the donors with those of the transfusion-receiving patients. CONCLUSIONS: Three transfusion-transmitted malaria cases were identified in China, all of which were due to the transfusion of blood donated by individuals who had contracted malaria outside the country. These cases can provide a reference for those faced with similar challenges in malaria case identification and classification in other regions. In addition, a stricter screening policy including the use of appropriate detection methods for malaria parasites should be developed and adopted for blood donation in regions undergoing malaria elimination.

Shrinking the malaria map in China: measuring the progress of the National Malaria Elimination Programme.

BACKGROUND: Remarkable progress has been made towards the elimination of malaria in China since the National Malaria Elimination Programme (NMEP) was launched in 2010. The incidence of locally-acquired malaria cases has declined rapidly and endemic areas have also dramatically shrunk. In total, 3 078 malaria cases were reported in 2014, but only 56 cases were indigenous. In order to further promote the elimination programme, we reviewed the progress of and experiences associated with malaria elimination in China, and identified the challenges and priorities for the next stage of the programme. METHODS: Data were collected from the web-based China Information System for Disease Control and Prevention, and the China Annual Report of Malaria Elimination. The progress towards the elimination of malaria from 2010 to 2014 was measured. RESULTS: During the implementation of the NMEP from 2010 to 2014, local malaria incidence has declined continuously, only remaining in the Yunnan Province and Tibet Autonomous Region in 2014. By the end of 2015, 75.6 % (1 636/2 163) of the malaria-endemic counties passed the sub-national elimination assessment. The main challenges are cases of border malaria and imported malaria from other countries. Sustainable support and investment from the government, the establishment of an effective surveillance and response system, and risk assessments for the potential reintroduction of malaria are priorities for the next stage of the elimination programme. CONCLUSIONS: The NMEP in China has been successfully implemented thus far and the malaria map has shrunk dramatically. The priorities for malaria elimination are interventions to block transmission at border areas, management of imported malaria cases, preventing malaria reintroduction, capacity building, and sustainability of malaria surveillance and response.

[Analysis of epidemic situation of malaria in Jiangsu Province from 2005 to 2014].

OBJECTIVE: To understand the epidemic situation and epidemiological characteristics of malaria in Jiangsu Province from 2005 to 2014, so as to provide the evidence for formulating and adjusting the strategies and measures on malaria elimination in this province. METHOD: The epidemiological data of malaria in Jiangsu province from 2005 to 2014 were collected, and the prevalence situation, infection sources as well as the temporal, regional and population distribution of the cases were analyzed. RESULT: A total of 5,069 malaria cases were reported in Jiangsu Province form 2005 to 2014, there were 3,422 cases (67.51%) of vivax malaria, 1,497 cases (29.53%) of falciparum malaria, and 150 cases (2.96%) that were unclassified. Among all the reported cases, 2,139 (42.20%) were local cases, 1,131 were (22.31%) imported cases from other places in China, and 1,799 (35.49%)were imported cases from abroad. There were 3,809 male cases and 1,260 female cases, with a sex ratio of 3.02:1. The patients were mainly aged from 25 to < 60 years (accounting for 67.15%), and were mainly young adult farmers (40.26%) and migrant workers (23.63%), who mainly distributed (accounting for 60.58%) in Xuzhou, Suqian, Huai'an, Suzhou and Nantong cities. The predominant malaria type from 2005 to 2009 were vivax malaria, while after 2010, it changed to falciparum malaria. CONCLUSIONS: The malaria epidemic situation has been effectively controlled in Jiangsu Province, which reflects the initiative achievements of malaria elimination. However, there are still many imported malaria cases from abroad, and the species of the Plasmodium are diverse. Therefore, the imported malaria from abroad still remains the key of malaria control in Jiangsu Province.

[Establishment of malaria early warning system in Jiangsu Province IV Implementation of key measures to eliminate malaria in Jiangsu Province in 2013].

OBJECTIVE: To promote the malaria control process in the malaria elimination stage in Jiangsu Province. METHODS: The data from the network reporting system of medical institutions, the disease prevention and control institutions at all levels, and the special reports system of parasitic diseases were collected and analyzed statistically. RESULTS: There were 341 malaria cases directly reported from the Jiangsu provincial network in 2013. All were laboratory-confirmed cases. Except one case of blood transfusion infection, the rest were imported malaria cases abroad. All the malaria cases were reported after diagnosis within 24 hours through the directly reported network, and the implementation rate was 100%. All the malaria cases had an epidemiological investigation within 3 days with the implementation rate of 100%; in which 334 (97.95%) cases were investigated within 2 days. All the cases had an epidemical investigation and disposition within 7 days with the implementation rate of 100%, in which 319 cases (93.55%) were completed within 5 days. CONCLUSIONS: The implementation rate of malaria elimination work mode has reached 100% in Jiangsu Province in 2013, and there are no local infected malaria cases for two consecutive years. However, the inspection and supervision of case investigation and epidemic investigation and disposal are still need to he strengthened.

[Epidemiological analysis of malaria prevalence in Jiangsu Province in 2014].

OBJECTIVE: To understand the malaria epidemic situation and characteristics in Jiangsu Province in 2014, so as to provide the evidence for formulating and adjusting appropriate strategies and measures for malaria elimination in this province. METHODS: The reported malaria cases from the Internet Reporting System and the epidemiological data of malaria in Jiangsu Province were collected and analyzed. RESULTS: A total of 355 malaria cases were reported in Jiangsu Province in 2014, which was increased by 4.11% comparing to that in 2013 (341 cases), and the malaria incidence was 0.046/10 000. All the 355 cases were imported from other countries, among which, 4 cases (1.13%) were from Southeast Asia; the other 351 cases (98.87%) were from 21 African countries. Though the cases were distributed in all the 13 prefecture-level cities in Jiangsu Province, the number of cases in 5 of them namely Huai' an, Nantong, Lianyungang, Yangzhou and Taizhou accounted for 63.38% (225/ 355). A total of 292 falciparum malaria cases, 4 tertian malaria cases, 10 quartan malaria cases, 46 ovale malaria cases and 3 mixed infection cases were confirmed after re-checked by Jiangsu Provincial Reference Lab of Malaria. The follow-up observation of the cases showed that among the 355 cases, 6 falciparum malaria cases recrudesced, and 4 ovale malaria cases and 1 tertian malaria case recurred. CONCLUSIONS: There have been no local malaria cases reported from Jiangsu Province in the last three years, indicating the object of malaria elimination has been achieved initiatively. However, there are still many imported malaria cases from other countries, with a diverse species of plasmodium. Therefore, the surveillance of the imported malaria, the training for diagnosis and treatment of malaria as well as the health education to the key population should be strengthened.

[Establishment of malaria early warning system in Jiangsu Province VII Eliminating malaria surveillance sentinels].

OBJECTIVE: To understand the epidemic situation and influencing factors of malaria in Jiangsu Province and grasp the regularity and trend of the epidemic. METHODS: According to the provincial malaria transmission situation and characteristics, Sihong County of Suqian City, which had more original cases, and Baoying County of Yangzhou City, which had more import cases, were chosen as the malaria surveillance sentinels at the state level; six counties, Yixing County of Wuxi City, Suining County of Xuzhou City, Wujin District of Changzhou City, Haian county of Nantong City, Ganyu County of Lianyugang City, and Xuyi county of Huaian City were chosen as the malaria surveillance sentinels at the provincial level. The data of basic status, blood tests of feverish patients, case studies of malaria patients, investigations and disposals of epidemic focuses and others were collected and analyzed. RESULTS: There were 92,484 blood test samples from feverish patients in the eight surveillance sentinels in 2014, and the average rate of blood tests was 1.15%. Totally 61 cases were plasmodium positive, and the positive rata was 0.07%. All of the 61 cases were foreign imported patients diagnosed by laboratory. After the direct network reporting, the review of the blood slides and epidemiological individual surveys were finished in 3 days, and the investigations and disposals of epidemic focuses were finished in 7 days. The epidemiological individual surveys of these 61 cases showed that 37.70% (23/61) of the first-time consultancy was mainly in the county level CDC, and 50.82% (31/61) in county level medical organizations. The making definite diagnosis of malaria also focused on the county level, 45.90% (28/61) in county level CDC and 47.10% (29/61) in county level medical organizations. The definite diagnostic rate of fist-time consultancy was 90.16% (55/61). Totally 48 malaria patients had been sent to abroad by their companies, and 34 had fellow crew. CONCLUSIONS: The malaria surveillance sentinels in Jiangsu Province play a good role on the surveillance function of malaria, and effectively promote the elimination of malaria in whole province. In the future, the malaria surveillance should establish a multi-sectoral cooperation and investigation mechanism, and strengthen the screening of the high-risk population and health education.

[Establishment of malaria early warning system in Jiangsu Province VI Regular surveillance of eliminating malaria and its effect].

OBJECTIVE: To analyze the regular surveillance and evaluate its effect during the elimination stage of malaria in Jiangsu Province from 2012 to 2014 and discuss the best way for surveillance and management, so as to provide the evidence for formulating and adjusting the strategy and methods for malaria elimination. METHOD: The data of network malaria reports, blood tests of feverish patients, epidemiology investigation forms of case study of malaria patients in the report system, and investigation and disposition forms of epidemic regions were collected and analyzed statistically. RESULTS: From 2012 to 2014, there were 894 malaria cases in total. Totally 1 625 034 feverish patients had blood tests, and 892 of them showed positive and the positive rate was 0.05%. The epidemiological case study showed that all the patients were foreign infection import patients except one was foreign import cases by blood transfusion. These cases were mainly distributed in Nantong City (125 cases), Yangzhou City (123 cases), Huai'an City (112 cases), Lianyungang City (111 cases) and Taizhou City (88 cases), and the total cases of the five cities accounted for 62.53% (559/894) of total cases of entire province. These cases were mainly diagnosed in country level CDC and medical organizations, and city level medical organizations. These units accounted for 87.02% of all the diagnostic organizations (778/894). CONCLUSIONS: From 2012 to 2014, there are no reports of local malaria infection cases in Jiangsu Province, meaning the preliminary realization of eliminating malaria. However, we still should strengthen the regular surveillance and treatment of import malaria cases.

[Establishment of early warning system of malaria in Jiangsu Province V Es- tablishment of prevention and control system of imported falciparum malaria].

OBJECTIVE: To establish a system of the prevention and control of imported falciparum malaria in Jiangsu Prov- ince and provide the new scientific basis for the prevention and control of imported falciparum malaria. METHODS: The data- bases for overseas labor companies and labors in Jiangsu Province were built and the health education was conducted to the overseas labors. The "1-3-7" elimination strategy was established. A weekly reporting system for malaria case details was es- tablished. A system for screening accompanies of imported malaria patients was established. RESULTS: At the end of 2013, the database of companies engaged in labor export was built and1 405 companies were incorporated into the database. The time interval between the symptom onset and the first health facility visit was reduced to 3.07 days in 2013. The time interval be- tween the first health facility visit to malaria diagnosis was reduced to 1.57 days in 2013. The rate of laboratory confirmation was increased to 100% in 2013, and there was a statistically significant difference among the rates of laboratory confirmation from 2009 to 2013 (χ2 = 36.35, P < 0.05). The proportion of severe imported falciparum malaria cases was decreased to 3.15% in 2013 and there was a statistically significant difference among the proportions of severe cases from 2009 to 2013 (χ2 = 301.16, P < 0.05). No death malaria case was reported in the whole province in 2013. CONCLUSION: Jiangsu Province has built a preliminary system of the prevention and control of imported falciparum malaria, which plays an important role in the prevention and control of overseas imported falciparum malaria.

[Surveillance of malaria in provincial surveillance sites in Jiangsu Province, 2013].

OBJECTIVE: To understand the epidemic situation and influencing factors of malaria in Jiangsu Province and grasp its epidemic regularity and trend. METHODS: According to the malaria prevalence in Jiangsu Province, 6 counties (city, district) including Yixing, Suining, Wujin, Hai'an, Ganyu and Xuyi were selected as provincial surveillance sites to survey malaria epidemic conditions. The basic information, blood test results of fever patients, case investigation, information of malaria patients, monitoring data of investigation and disposition of the malaria focus were collected and analyzed. RESULTS: In 2013, the blood tests of 66 723 fever patients were performed, the average blood smear checking rate was 1.10%, and the average positive rate was 0.08% (52 plasmodium positive individuals) in the 6 areas. For these 52 plasmodium positive individuals, the blood retests and case investigations were completed within 3 days after these cases were reported by the network system, and the investigation confirmed that they were foreign imported malaria cases. The malaria focus investigation and disposition were finished within 1 week and the data were reported by the Parasitic Diseases Information System. Four of 52 cases were recrudescence during the follow-up. Among the 52 cases, 20 people went abroad themselves and 4 were labors of private enterprises, 21 people came back without the accompanied. CONCLUSIONS: With the development of the malaria elimination program in Jiangsu Province, the eliminating malaria "targeted 1-3-7" working pattern has been comprehensively implemented. The personnel monitoring for labors who returned from overseas working will be a key in the future.

[Establishment of malaria early warning system in Jiangsu Province III effect of automatic early warning information system on the response of malaria elimination].

OBJECTIVE: To evaluate the effect of automatic early warning information system on the response of malaria elimination in Jiangsu Province through the operation of the national automatic early warning system of infectious diseases. METHODS: The malaria early warning information was collected from the automatic early warning information subsystem in the national information system for diseases control and prevention. Malaria early warning signals were analyzed from September 1 to December 31, 2012. The statistical analysis was conducted for the completion rates of case investigation within 3 days before and after the application of malaria early warning information system. RESULTS: Jiangsu Province received 85 mobile phone short messages (SMS) of malaria case from early warning system from September 1 to December 31, 2012. After judgments, 23 cases were deleted including 8 repeated cases and 15 cases that were excluded through the microscopy examination and epidemiological investigation by the confirmation of county CDC. From July to December in 2012, the monthly completion rates of case investigation within 3 days were 55.56%, 78.57%, 90.00%, 100%, 100% and 100%, respectively. The completion rates of case investigation within 3 days in July, August, September and October were significantly different by chi2 test ( chi2 = 10.66, P < 0.05). The completion rates of foci investigation and action within 7 days in Jiangsu Province were all 100% from July to December in 2012. CONCLUSIONS: The completion rates of case investigation within 3 days are associated with SMS from the early warning system. The malaria warning system from the national infectious diseases can effectively improve the response to malaria cases for primary CDC. It also plays an important role for the timely confirmation and diagnosis of malaria cases.

[Epidemiological analysis of malaria prevalence in Jiangsu Province in 2013].

OBJECTIVE: To understand the malaria epidemic situation and characteristics in Jiangsu Province in 2013, so as to provide the evidence for formulating and adjusting effective malaria elimination strategies and measures. METHODS: The reported malaria cases from the Internet Reporting System and the epidemiological data of malaria in Jiangsu Province were collected and analyzed. RESULTS: A total of 341 malaria cases were reported in Jiangsu Province in 2013 with the incidence of 0.050/10 000, which increased by 72.22% compared with that in 2012 (198 cases). All the cases were imported from other countries including one infected by blood transfusion resulted from imported infection. The cases were mainly distributed in Lianyungang City (15.84%, 54 cases), Nantong City (14.08%, 48 cases), Yangzhou City (14.08%, 48 cases), Huaian City (11.44%, 39 cases) and Yancheng City (8.50%, 29 cases). All the cases were confirmed in Jiangsu Provincial Reference Laboratory and there were 286 cases of Plasmodium falciparum, 8 cases of P. vivax, 9 cases of P. malariae, 30 cases of P. ovale and 8 cases of mixed infections. CONCLUSIONS: There were no local malaria cases reported from Jiangsu Province in the last two years which reflected effective achievements of malaria elimination. However, the situation of imported malaria is more serious and the species of infected plasmodium are more diverse. Imported malaria from other countries remains the key of malaria control in Jiangsu Province.

[Study on TaqMan-MGB real-time fluorescence quantitative PCR to detect gene mutation of kdr from Anopheles sinensis].

OBJECTIVE: To establish a Real-time Fluorescence Quantitative PCR to detect the kdr gene mutation in Anopheles sinensis. METHODS: One pair of primers and three TaqMan-MGB probes were designed based on kdr gene and its L1014 locus mutations of A. sinensis. After optimization, the Real-time Fluorescence Quantitative PCR was verified by using 6 types of A. sinensis samples with different kdr gene types. Additionally, 50 laboratory samples and 113 field samples were tested by this method. RESULTS: The established Real-time Fluorescence Quantitative PCR could identify 6 different kdr gene types in A. sinensis. The mutation could be detected by single-tube Fluorescence Quantitative PCR, and the detail mutation type could be further identified by double-tube Fluorescence Quantitative PCR. By using this method, 50 laboratory samples were confirmed as wild type homozygotes. Among 113 field samples, 12 were wild type homozygotes, others were L1014F or L1014C mutations, and the total mutation frequency was 87.61%. CONCLUSION: The new established TaqMan-MGB Real-time Fluorescence Quantitative PCR can be used to detect the kdr gene L1014 mutations of A. sinensis.

[Establishment of malaria early warning system in Jiangsu Province II application of digital earth system in malaria epidemic management and surveillance].

OBJECTIVES: To explore a new mode of malaria elimination through the application of digital earth system in malaria epidemic management and surveillance. METHODS: While we investigated the malaria cases and deal with the epidemic areas in Jiangsu Province in 2011, we used JISIBAO UniStrong G330 GIS data acquisition unit (GPS) to collect the latitude and longitude of the cases located, and then established a landmark library about early-warning areas and an image management system by using Google Earth Free 6.2 and its image processing software. RESULTS: A total of 374 malaria cases were reported in Jiangsu Province in 2011. Among them, there were 13 local vivax malaria cases, 11 imported vivax malaria cases from other provinces, 20 abroad imported vivax malaria cases, 309 abroad imported falciparum malaria cases, 7 abroad imported quartan malaria cases (Plasmodium malaria infection), and 14 abroad imported ovale malaria cases (P. ovale infection). Through the analysis of Google Earth Mapping system, these malaria cases showed a certain degree of aggregation except the abroad imported quartan malaria cases which were highly sporadic. The local vivax malaria cases mainly concentrated in Sihong County, the imported vivax malaria cases from other provinces mainly concentrated in Suzhou City and Wuxi City, the abroad imported vivax malaria cases concentrated in Nanjing City, the abroad imported falciparum malaria cases clustered in the middle parts of Jiangsu Province, and the abroad imported ovale malaria cases clustered in Liyang City. CONCLUSION: The operation of Google Earth Free 6.2 is simple, convenient and quick, which could help the public health authority to make the decision of malaria prevention and control, including the use of funds and other health resources.

[Epidemiological analysis of malaria prevalence in Jiangsu Province in 2011].

OBJECTIVE: To analyze the malaria prevalence and epidemic characteristics in Jiangsu Province in 2011 so as to provide a basis for drawing up and adjusting effective malaria elimination strategies and measures. METHODS: The reported malaria cases from the Internet reporting system and epidemiological data of malaria were collected and analyzed statistically in Jiangsu Province. RESULTS: A total of 374 malaria cases were reported in Jiangsu Province in 2011 with the incidence of 0.05/10 000 which was similar to the number of cases in 2010. There were 13 cases of local vivax malaria which decreased by 87.00% compared with 100 cases in 2010. There were 361 imported cases including 309 imported falciparum malaria cases which increased by 49.00% compared with 207 cases in 2010. The imported falciparum cases mainly distributed in Yangzhou, Nantong, Huai' an and Taizhou cities which are located in central Jiangsu and coastal areas of northern Jiangsu. The number of imported falciparum malaria cases of these four cities accounted for 66.02% among the total cases in Jiangsu Province. There were 7 imported quartan malaria cases that were first reported and 14 imported ovale malaria cases. CONCLUSIONS: The local vivax malaria infections in Jiangsu Province decrease significantly and the endemic areas reduce significantly. However the imported falciparum malaria cases are increasing significantly year by year and the infected plasmodium parasites show diversities. Therefore, to achieve the target of malaria elimination in Jiangsu on schedule, it needs to continue to strengthen the personnel training of primary health care facilities and the disease control agencies, and strengthen the health education for export staffs and the monitoring and surveillance of the returnee.

[Analysis of overseas imported malaria situation and implication for control in Jiangsu Province, PR China].

OBJECTIVE: To analyze the epidemiological characteristics of overseas imported malaria in Jiangsu Province and explore the strategies and priorities in prevention and control, so as to provide the evidence for improving the diagnosis, treatment and management of imported malaria. METHODS: The data of overseas imported malaria as well as the case epidemiological investigation in Jiangsu Province from July 18, 2011 to June 30, 2012 were collected and analyzed descriptively for the species composition, original countries, population distribution, regional distribution, onset time, diagnosis and treatment, channels to go abroad, and counterparts returned together with the patients. RESULTS: A total of 233 overseas imported malaria cases were reported, and 226 cases (97.0%) were imported from African countries. A total of 208 cases (89.3%) were falciparum malaria, and 224 cases (96.1%) were laboratory-confirmed. The imported malaria cases were young adults who were mainly migrant farmer and skilled male workers. There was no significant seasonal variation for onset time. Totally 145 cases (62.2%) got malaria onset in 20 days after returning home. The median time from onset to seeing doctor was two days and the median time from seeing doctor to being diagnosed was one day. The first visit health facilities by the patients were relatively scattered and the diagnostic health facilities were mainly medical institutions and CDC at the county level and above (220 cases, accounting for 94.4%). The ratio of standard treatment after malaria diagnosis was 100%. A total of 205 cases (88.0%) were workers dispatched to abroad as labor export by the company, and 142 cases (60.9%) cases had counterparts returned together. CONCLUSIONS: The situation of overseas imported malaria in Jiangsu Province is severe. It is necessary to further strengthen the professional training and multi-sectoral cooperation, establish the collaborative investigation mechanism for high-risk groups, and take effective prevention and control measures to reduce the risk of overseas imported malaria.

[Detection of Plasmodium sporozoites in mosquitoes by using fluorescent quantitative PCR].

OBJECTIVE: To establish a fluorescent quantitative PCR (FQ-PCR) method for quantitative detection and species identification of Plasmodium sporozoites in Anopheles mosquitoes. METHODS: One pair of human Plasmodium genus-specific primers based on 18S rRNA genes were used and the reaction system and reaction condition of FQ-PCR were optimized by using the mixture of Plasmodium 18S rRNA gene recombinant plasmids and Anopheles DNA as a template. The specificity was verified by using four Plasmodium spp. 18S rRNA gene plasmid DNA as well as mosquito DNA and the Plasmodium species was identified according to the value of melting temperature (Tm). The standard curve was made by using P. vivax 18S rRNA gene recombinant plasmids which were serially diluted by negative Anopheles DNA as a template. The sensitivity was analysed by using plasmid DNA and laboratory infected sporozoite positive mosquito DNA, respectively. The different parts and different amounts of Anopheles DNA were added into the reaction system to investigate the influence of Anopheles DNA on the assessment. RESULTS: There was no specific amplification for mosquito DNA and human blood DNA. There was specific amplification for Plasmodium 18S RNA gene recombinant plasmids and the Tm(s) of P. malariae, P. falciparum, P. ovale and P. vivax were 71.0, 72.7, 73.9 degrees C and 75.9 degrees C, respectively, which were easy to be identified. The standard curve indicated a good linear relationship between the cycle threshold (Ct) and template concentration (r = -0.99). The sensitivity was 50 copies of plasmid DNA or one sporozoite positive mosquito DNA diluted by 32 times of mosquito DNA. Anopheles DNA could inhibite the FQ-PCR reaction. The Ct value of amplification showed a good reproducibility both within the same experiment and among different experiments. CONCLUSION: The novel SYBR Green I based FQ-PCR method developed in this study shows a high sensitivity and specificity and it can be used for quantitative detection and species identification of sporozoites in mosquitoes.

[Field application of multiplex PCR to distinguish Plasmodium vivax and Plasmodium falciparum].

OBJECTIVE: To explore the application value of multiplex PCR in the diagnosis of malaria in field. METHODS: The plasmodium genus-specific primer, Plasmodium vivax, P. falciparum species-specific primers were synthesis based on the specific target segments of small subunit of 18 S rRNA ribosomal. The multiplex PCR system was optimized, and a PCR diagnostic method of malaria was established based on the genomic specific DNA fragment of P. vivax, and P. falciparum was amplified in the same PCR reaction system. The sensitivity, specificity, and the value of field application of the multiplex PCR were investigated. RESULTS: The sizes of amplification products of multiplex PCR amplifying genomic DNA of P. vivax and P. falciparum were 833 bp and 1 451 bp, respectively, and the amplification did not take place with the samples DNA of P. berghei, P. cynomolgus and healthy human blood. The sensitivities of multiplex PCR to detect P. vivax and P.falciparum were 1.1 x 10(-6) and 5.6 x 10(-7) parasitemia, respectively. Compared with the microscopic examination, the positive rate of multiplex PCR to detect 119 cases of field samples was 54%, missed diagnosis rate was 0.8%, and the misdiagnosis rate was naught, while the positive rate of the microscopic examination was 53%, its misdiagnosis rate and missed diagnosis rate were 1.7% and 3.4%, respectively. The compliance rate between the multiplex PCR and microscopic examination was 94%. CONCLUSION: The multiplex PCR for detecting malaria is simple, rapid, specific, sensitive, etc., which is suitable for the differential diagnosis of suspected cases, and molecular epidemiology investigation.

[Analysis of seasonal variability of vivax malaria by circular distribution method in Jiangsu Province from 1961 to 2010].

OBJECTIVE: To study the law of seasonal variability of vivax malaria in Jiangsu Province from 1961 to 2010, so as to provide the reference for improving malaria control. METHODS: The data of vivax malaria incidence from the epidemic reporting system of Jiangsu Province were collected and analyzed to understand the month morbidity, peak prevalence time and mean durations, and the peak incidence durations every 10 years with the circular distribution method. RESULTS: Vivax malaria appeared obvious seasonal variability (P < 0.01) with different peak time (P < 0.01). The average peak time occurred on August 9th. The morbidity duration was shortest (75 d) in 1963 and longest (123 d) in 2010 with a mean duration of 93 days, and the peak duration extended 146 days in 10 years from 2001-2010 compared with that from 1960-1970. CONCLUSION: The incidence of vivax malaria presents obvious seasonal peak in Jiangsu Province and its peak concentrates in mid-July to early August, and in nearly 10 years, the days of peak incidence of vivax malaria extended.