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Objective To analyze the changes of small molecular metabolites in the larvae of a deltamethrin-sensitive strain of Anopheles sinensis following exposure to deltamethrin, so as to provide the scientific basis for investigating the metabolic pathway and screening metabolic markers of deltamethrin in An. sinensis. Methods The 50% and 75% lethal concentrations (LC50 and LC75) of deltamethrin against the larvae of a deltamethrin-sensitive strain of An. sinensis were calculated in laboratory. The type and content of An. sinensis larvae metabolites were detected using high performance liquid chromatography and mass spectrometry (LC-MS/MS) following exposure to deltamethrin at LC50 and LC75 for 30 min and 24 h, and the changes of metabolites were analyzed. Results The LC50 and LC75 values of deltamethrin were 4.36 × 10-3 µg/mL and 1.12 × 10-2 µg/mL against thelarvae of a deltamethrin-sensitive strain of An. sinensis. Following exposure of the larvae of a deltamethrin-sensitive strain of An. sinensis to deltamethrin at LC50 and LC75 for 30 min, the differential metabolites mainly included organic oxygen compounds, carboxylic acid and its derivatives, fatty acyl and pyrimidine nucleotides, with reduced glucose levels. Following exposure for 24 h, the differential metabolites mainly included organic oxygen compounds, carboxylic acid and its derivatives, aliphatic acyl and purine nucleotides, with increased glucose level detected. Conclusion Carbohydrate, carboxylic acid and its derivatives, fatty acyls, amino acids and their derivatives may play important roles in deltamethrin metabolism in the larvae of a deltamethrin-sensitive strain of An. sinensis.
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Objective To investigate the distribution and density of Culex mosquito populations and the resistance of Culex pipiens pallens to insecticides in Jiangsu Province in 2018 and 2019. Methods During the period from June to October in 2018 and 2019, six counties (districts, cities) were sampled in southern, northern and central Jiangsu Province as surveillance sites. The density of Culex mosquitoes was measured overnight using the light trapping technique. In addition, Culex pipiens pallens mosquitoes were collected from Hai’an of Nantong City and Yandu District of Yancheng City, central Jiangsu Province, and the sensitivity of female first filial generations to dichlorodiphenyltrichloroethane (DDT), malation, proposur, beta cypermethrin and deltamethrin was tested using the standard WHO insecticide susceptibility test assay. Results A total of 104 423 Culex mosquitoes were captured in six surveillance sites of Jiangsu Province in 2018 and 2019, and Culex quinquefasciatus (49.11%), Culex pipiens pallens (28.38%), and Culex tritaeniorhynchus (21.04%) were predominant species. The density of Culex mosquitoes started to increase since early June, peaked in July and tended to be low in late October. Culex pipiens pallens mosquitoes captured from Hai’an was susceptible to malation, while those from Yandu District were moderately resistant to malation. Culex pipiens pallens mosquitoes from both Yandu and Hai’an were moderately resistant to proposur, and were resistant to DDT, beta cypermethrin and deltamethrin. Conclusions Culex quinquefasciatus, Culex pipiens pallens and Culex tritaeniorhynchus are predominant Culex species in Jiangsu Province. Culex pipiens pallens is resistant to DT, beta cypermethrin and deltamethrin in central Jiangsu Province.
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Malaria was one of the major infectious diseases in Jiangsu Province, where Anopheles sinensis and An. anthropophagus are main vectors for malaria transmission. Following the concerted efforts for decades, the goal of malaria elimination was achieved in Jiangsu Province in 2019, and the vector control strategy has played a vital role during the progress towards malaria elimination in Jiangsu Province. Hereby, we review the historical distribution and ecological features of An. sinensis and An. anthropophagus and describe vector control strategies at different stages of malaria control in Jiangsu Province. In addition, the advances in the research of vector biology and control in Jiangsu Province are discussed, including vector identification, strain colonization, susceptibility to malaria parasites and insecticide resistance.
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Objective To analyze the results of samples testing of Jiangsu Provincial Malaria Diagnostic Reference Laboratory in 2017, so as to provide the evidence for improving the malaria diagnostic performance in this province. Methods The samples of reported malaria cases in Jiangsu were collected by the provincial reference laboratory (PRL) in 2017. The microscopy and nucleic acid test were performed to confirm the infection of Plasmodium species of each case, while Plasmodium antigen tests (rapid diagnostic test, RDT) were performed as well. The detection results were analyzed among different areas and different species. Results Totally 242 malaria cases were reported and the samples were collected by PRL in 2017. A total of 239 cases were confirmed Plasmodium infections, including 163 cases of Plasmodium falciparum infection, 21 cases of P. vivax infection, 11 cases of P. malariae infection, 43 cases of P. ovale infection, and 1 case of P. falciparum and P. ovale mixed-infection. The diagnostic coincidence rates of reported malaria case in 13 prefectures with districts were all > 80%, and the total coincidence rate was 88.8%. The species diagnostic coincidence rates of P. falciparum, P. vivax, P. malariae, and P. ovale were 98.8%, 57.1%, 63.6%, and 81.4% respectively, and the detection rates by RDT to those four species infections were 95.7%, 85.0%, 63.6% and 79.1% respectively. Conclusions In 2017, the malaria diagnostic quality of medical technicians is generally high in Jiangsu Province. However, the diagnostic capacity is slightly different among different regions, and the ability to identify non- P. falciparum parasites remains to be improved. RDT is not ideal for the detection of non-P. falciparum infection. In the current stage of malaria elimination, the malaria diagnostic capacity of technicians in all the sectors should be strengthened and maintained.
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Objective To analyze the results of samples testing of Jiangsu Provincial Malaria Diagnostic Reference Laboratory in 2017, so as to provide the evidence for improving the malaria diagnostic performance in this province. Methods The samples of reported malaria cases in Jiangsu were collected by the provincial reference laboratory (PRL) in 2017. The microscopy and nucleic acid test were performed to confirm the infection of Plasmodium species of each case, while Plasmodium antigen tests (rapid diagnostic test, RDT) were performed as well. The detection results were analyzed among different areas and different species. Results Totally 242 malaria cases were reported and the samples were collected by PRL in 2017. A total of 239 cases were confirmed Plasmodium infections, including 163 cases of Plasmodium falciparum infection, 21 cases of P. vivax infection, 11 cases of P. malariae infection, 43 cases of P. ovale infection, and 1 case of P. falciparum and P. ovale mixed-infection. The diagnostic coincidence rates of reported malaria case in 13 prefectures with districts were all > 80%, and the total coincidence rate was 88.8%. The species diagnostic coincidence rates of P. falciparum, P. vivax, P. malariae, and P. ovale were 98.8%, 57.1%, 63.6%, and 81.4% respectively, and the detection rates by RDT to those four species infections were 95.7%, 85.0%, 63.6% and 79.1% respectively. Conclusions In 2017, the malaria diagnostic quality of medical technicians is generally high in Jiangsu Province. However, the diagnostic capacity is slightly different among different regions, and the ability to identify non- P. falciparum parasites remains to be improved. RDT is not ideal for the detection of non-P. falciparum infection. In the current stage of malaria elimination, the malaria diagnostic capacity of technicians in all the sectors should be strengthened and maintained.
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With the long-term and widespread application of antimalarial drugs, Plasmodium falciparum has gradually produced resistance to antimalarial drugs. At present, there are more researches on the molecular markers of P. falciparum drug resistance, while less attention has been paid to the molecular markers of non-P. falciparum drug resistance. In order to provide the reference for rational drug use in clinical treatment and reference for molecular monitoring of antimalarial drug sensitivity of non-P. falciparum, this paper reviews the researches on the common molecular markers related to non-P. falciparum drug resistance.
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To establish a systemized malaria biobank with well-rounded epidemiologic data and a computer-aid management system, thus to provide qualified sources for malaria elimination and human malaria research.The malaria biobank was based on the platform of Jiangsu Institute of Parasitic Diseases. The blood smear samples, dried blood samples, whole blood samples and parasite strains isolated from patients (from both local and imported cases) were collected since 2011 according to a standardized operational procedure. The biobank management software was applied to input of the epidemiological data and samples, and the quality of samples was monitored regularly.A standard malaria biobank was established. The Information Management System was applied to input, storage and output of samples. Totally 99.42% (2 223/2 236) of the blood smear samples, 92.58% (2 070/2 236) of the dried blood samples, 94.50% (2 113/2 236) of whole blood, and 2.06% (46/2 236) of the isolated stains in 2 236 reported cases were included in the malaria biobank in Jiangsu Province from 2011 to 2017. Based on the malaria biobank, 99.42% (2 223/2 236) of the blood smears and 82.74% (1 850/2 236) of DNA (from dried blood and whole blood samples) from malaria patients in Jiangsu Province were re-checked. Moreover, the samples in the malaria biobank were used in the studies of the mechanism of parasite drug resistance, malaria molecular epidemiology, and diagnosis technology development and evaluation.The establishment of malaria biobank provides a guarantee for malaria elimination in Jiangsu Province and also provides a qualified resource for malaria research.
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To analyze the vector surveillance results during the stage of malaria elimination, so as to provide the evidence for assessing the local transmission risk of imported malaria and carrying out the surveillance work after malaria elimination in Jiangsu Province.From 2011 to 2017, the mosquito population was monitored and human biting rates were calculated by the half overnight human baiting trapping method and overnight lamp trapping method in 7 surveillance sites from June to October. The insecticide resistance level was tested by the force contact method recommended by WHO.A total of 5 106 Anopheles mosquitoes were captured by the half over-night human baiting trapping method in the 7 sites from 2011 to 2017, and all the mosquitoes were identified as Anopheles sinensis. The annual human biting rates were 1.075, 0.786, 1.057, 0.787, 0.790, 1.797 and 1.185 mosquitoes/ (human·hour), respectively. Totally 28 186 Anopheles mosquitoes were caught by the overnight lamp trapping method, and all the mosquitoes were An. sinensis. The densities of Anopheles mosquitoes were 57.950, 50.932, 14.800, 4.405, 58.070, 72.406, and 17.145 mosquitoes/ (night·lamp), respectively. In 2012, the resistance indexes of An. sinensis to deltamethrin, DDT and malathion were at R level in Jiangsu Province.The major vector is An. sinensis and no An. anthropophagus is found in Jiangsu Province. An. sinensis has a high level of resistance to deltamethrin, DDT and malathion.
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There were vivax malaria, falciparum malaria, and malariae malaria epidemic in Jiangsu Province, and vivax malaria was the dominant disease. Anopheles sinensis and An. anthropophagus were malaria-transmitted vectors. Since the founding of People’s Republic of China, there have been two major malaria outbreaks in Jiangsu Province, when the highest annual malaria incidence reached up to 24.95%. According to prevention and control principles of “adjusting measures to local conditions, giving different guidance to different categories and highlighting key points”, during the epidemic outbreak stage, the largescale malaria prevention and control measures were implemented for all the residents who were target population in Jiangsu malaria-endemic areas. During the basic eradication stage, the targeted prevention and control measures had been carried out according to the different epidemic features to gradually consolidate the achievement of prevention and control in Jiangsu Province. In the malaria elimination stage, Jiangsu Province focused on controlling of the source of infection and malaria surveillance. According to the “1-3-7 targeted elimination” work model, the management of infectious sources and investigation and disposal of foci were carried out for each epidemic focus to block the malaria transmission. By the end of 2017, there had been no indigenous malaria cases for the six consecutive years in Jiangsu Province. All the 13 cities have passed the assessment of malaria elimination of Jiangsu Province. Although Jiangsu Province has achieved the goal of malaria elimination, it is urgent and necessary to maintain and improve malaria surveillance capabilities to prevent malaria reintroduction.
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Objective To explore the expression characteristics of cytochrome P450(CYP)candidate genes(CYP6M3, CYP6Y1,CYP6P5,CYP4H14,CYP4G17,CYP12F16)in Anopheles sinensis.Methods The samples were collected from dif-ferent developmental stages(eggs,larvae,pupae and adult mosquitoes(females and males)),and different tissues(salivary glands,malpighian tubes,midguts,ovaries,and fat bodies)of An.sinensis and the female adult mosquitoes exposed by differ-ent insecticide doses(0,1.25,3.75,6.25,12.5μg/bottle)and time points(0,5,15,30,60 minutes),then the total RNA was extracted. Quantitative reverse transcription PCR(qPCR)assay was used to analyze the relative expressions of six CYP genes in An.sinensis at different developmental stages,tissues and different insecticide exposure doses and time.Results The expressions of CYP6M3 and CYP6Y1 in the male adult mosquitoes were the highest,the expression of CYP6M3 gene in the males was 35.1 times higher than that in the females,the expression of CYP6Y1 in the males was 61.4 times higher than that in the females;the expression level of CYP4H14 in the larvae was the lowest,the expression of CYP4H14 in the females was 22.5 times higher than that in the fourth instar larvae.The expressions of candidate CYP genes in different tissues of An.sinensis were significantly different,the expression of CYP6M3 in the malpighian tubule was 38.9 times higher than that in the ovary,the ex-pression of CYP6Y1 in the fatbody was 9.1 times higher than that in the ovary,the expression of CYP4G17 was 4.6 times higher than that in the ovary,and the expression of CYP12F16 was 4.4 times higher thanthat in the ovary.The exposure to different in-secticide doses and time showed some induction effects in the expressions of candidate CYP genes,which affected the expres-sions of candidate CYP genes in An.sinensis.Conclusion The expression of candidate CYP genes varies significantly in differ-ent developmental stages and various tissues of An.sinensis,and exposure to deltamethrin at various doses and time points af-fects CYP genes expression in An.sinensis.