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Objective To compare the genetic diversity of imported Plasmodium falciparum by Polyα and TAA87 microsatellite markers in Southeast Asian and African geographical isolates. Methods Ninety-two and 126 filter paper samples from patients infected with P. falciparum from Southeast Asia (Myanmar) and Africa (Ghana) were collected, respectively. Two neutral microsatellite loci, Polyα and TAA87 were amplified by PCR. The length of PCR fragments was detected by capillary electrophoresis. The allele frequency and expected heterozygosity (He) were calculated by Excel 2010 and GenALEx 6.0 software. Results A total of 146 P. falciparum samples were analyzed as single infection samples with a total of 26 alleles in locus Polyα and 12 alleles in locus TAA87. The mean He value of the two loci was 0.86 ± 0.02. Ten alleles in locus Polyα and 8 alleles in locus TAA87 were distributed in Myanmar isolates, with the He values of 0.86 and 0.81 respectively. Fifteen alleles in locus Polyα and 11 in locus TAA87 were detected in Ghana isolates, with the He values of 0.91 and 0.86 respectively. In addition, the haplotype of 174 bp (Polyα) and 113 bp (TAA87) were only detected in Myanmar isolates with more than 17% gene frequency, whereas they were absent in Ghana isolates. Conclusions The two different geographical sources of imported P. falciparum strains have different allele frequencies and haplotypes at the two neutral microsatellite markers, Polyα and TAA87. Therefore, these two microsatellite loci may be considered as the potential molecular marker candidates for identifying P. falciparum strains with different geographical sources.
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Objective To compare the genetic diversity of imported Plasmodium falciparum by Polyα and TAA87 microsatellite markers in Southeast Asian and African geographical isolates. Methods Ninety-two and 126 filter paper samples from patients infected with P. falciparum from Southeast Asia (Myanmar) and Africa (Ghana) were collected, respectively. Two neutral microsatellite loci, Polyα and TAA87 were amplified by PCR. The length of PCR fragments was detected by capillary electrophoresis. The allele frequency and expected heterozygosity (He) were calculated by Excel 2010 and GenALEx 6.0 software. Results A total of 146 P. falciparum samples were analyzed as single infection samples with a total of 26 alleles in locus Polyα and 12 alleles in locus TAA87. The mean He value of the two loci was 0.86 ± 0.02. Ten alleles in locus Polyα and 8 alleles in locus TAA87 were distributed in Myanmar isolates, with the He values of 0.86 and 0.81 respectively. Fifteen alleles in locus Polyα and 11 in locus TAA87 were detected in Ghana isolates, with the He values of 0.91 and 0.86 respectively. In addition, the haplotype of 174 bp (Polyα) and 113 bp (TAA87) were only detected in Myanmar isolates with more than 17% gene frequency, whereas they were absent in Ghana isolates. Conclusions The two different geographical sources of imported P. falciparum strains have different allele frequencies and haplotypes at the two neutral microsatellite markers, Polyα and TAA87. Therefore, these two microsatellite loci may be considered as the potential molecular marker candidates for identifying P. falciparum strains with different geographical sources.
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To assess the efficacy of quarantine for acute hemorrhagic conjunctivitis (AHC)outbreaks control in schools,by using the Compartment Model.Through combining the characteristics of both AHC and compartment model,we built a susceptive-infective-removal (SIR) model suited for AHC outbreaks control in schools,and then quarantine was added into the model to develop a susceptive-infective-quarantine-removal (SIQR) model.An outbreak of AHC in Changsha in 2011 was employed as a sample to assess the effect of quarantine for the prevention and control of AHC.Basic reproduction number (λ 0) of the AHC outbreak without intervention was 6.80,thus the transmission speed of the disease became quite fast.If no intervention had been adopted,almost all the students,faculties and staff members would have been infected within 23 days,and the accumulative cases would become 738,with the total attack rate (TAR) as 99.73％.The peak of the outbreak was at Sep.11th and the number of new cases was 126 on that day.The efficacy would have been different if quarantine forces had been taken at different time and differently.The bigger and earlier the quarantine force had been adopted,the lower morbidity peak and the smaller TAR would have been appeared,with better efficacy of outbreak control.If the quarantine rate had been taken at the level of 90％ on the sixth day,the accumulative case would have been reduced to 132 and the TAR had become 17.84％ consequently.Quarantine program could be used as a main intervention approach to be employed for ACH outbreak at schools.
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In order to investigate the transmission risk of H5N1 avian influenza viruses (AIV) from sewage in Changsha poultry markets, the evolution relationship and molecular characteristics of non-structural (NS) genes of H5N1 AIV from sewage were analyzed. Nine H5N1 AIV environmental sewage specimens were collected from Changsha poultry markets. The NS genes were amplifyed by PCR and then sequenced with TA cloning. Amino acid(aa) sequence alignment and phylogenetic tree analysis were conducted by Lasergene and Mega5 software. Eight NS genes TA cloning were constructed successfully. Phylogenetic tree indicated that they were belonged to the allele A subgroup. Aa homology analysis showed 90.1% 92.5% identity in NS1 proteins and 91.0% - 92.6% identity in NS2 proteins compared with reference viruses of the allele A (A/chicken/ Hubei/ w h/ 1999). The homologies of the amino sequences of NS1 and NS2 in this study were 93.8%-100.0% and 98.4%-100.0%, respectively. The C terminal of all eight H5N1 NS1 proteins from sewage in poultry markets carried a ESEV of PL motif and the 92 amino acids were E, furthermore, the 80 to 84aa were missed which were the characteristics of highly pathogenic AIV. The NS genes of H5N1 AIV from sewage in poultry markets have molecular characteristics of highly pathogenic and have the potential risk of H5N1 virus spreading.
Subject(s)
Animals , Amino Acid Sequence , Influenza A Virus, H5N1 Subtype , Chemistry , Classification , Genetics , Influenza in Birds , Virology , Molecular Sequence Data , Phylogeny , Poultry , Sequence Homology, Amino Acid , Sewage , Virology , Viral Nonstructural Proteins , Chemistry , GeneticsABSTRACT
Objective To investigate the risk of H5Nl subtype avian influenza virus (AIV)transmission in the poultry market environment in Changsha city.H5N1 antibody levels among the groups related occupational exposure and AIV nucleic acid in the environment of poultry markets were detected.The characteristics of hamagglutinin (HA) genes of H5N1 AIV in the environment were analyzed.Methods One district and one county from Changsha city were selected randomly and two poultry markets at inner city or township levels were selected in the same district or county respectively.H5N1 antibody of the occupational exposure groups in the poultry market was tested and AIV nucleic acid in the poultry market environnent monitored.One hundred and two blood samples of the occupational exposure groups were tested for H5N1 antibody with single radioimmunoassay diffusion hemolysis (SRH) while 160 environment samples(from sewage,birds stools,feathers and smearing samples of poultry cages) in the poultry market were also detected for AIV nucleic acid with real-time PCR method.Four sewage samples of H5N1 subtype AIV were collected from poultry markets in Changsha,and the HA genes of H5N1 subtype AIV amplified by RT-PCR and then sequenced with TA cloning.Amino acid sequence alignment and phylogenetic tree analysis were conducted by Lasergene and Mega 5.0 software.Results The results through H5N1 antibody monitoring program showed that H5N1 antibody positive rates from workers were 25.5％ (26/102),50.0％ (9/18) and 25.4％ (17/67) respectively in the poultry markets of township and inner cities.H5N1 antibody positive rate in the township poultry markets was higher than in the inner cities poultry markets.Results from the surveillance on AIV nucleic acid showed that the overall H5 subtype positive rate in Changsha poultry markets was 31.3％ (50/160),and the positive rate of townships poultry markets was 37.3％ (31/83 ),which were both higher than those from the inner cities poultry markets (24.7％,19/77).H5 subtype AIV positive rate was different in the tested specimens,with ranking of positive rates were sewage (50.0％,24/48),feathers (44.5％,4/9 ),birds stools ( 29.8％,14/47) and smearing samples of poultry cages (14.3％,8/56),with statistically significant differences (P＜0.01).Four H5N1 HA genes TA cloning were successfully constructed and identified as Eurasian branch,similar to viruses isolated in mainland China and Hong Kong in the same group,according to genetic analysis.Sequence data of the four HA genes showed the same feature of high pathogenicity,compared to the H5N 1 AIV from mainland China of human origin.The receptor specificities were still with avian influenza origin (QSG)and the connecting peptide between HA1 and HA2 possessing the polybasic motif (RERRRKK or RERRGKK).Conclusion One of the reasons for H5N1 antibody positive rate of 25.5％ among poultry markets workers was that there were large numbers of H5N 1 subtype AIV detected in the environment of poultry markets and HA genes of H5N 1 subtype AIV in the poultry markets environment carried molecular characteristics of highly pathogenic which could increase the risk for H5N1 subtype AIV transmission in the environment of poultry markets.
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To simulate intervention measures in controlling an outbreak of acute hemorrhagic conjunctivitis on one school campus by using the Susceptible-Infected-Recovered (SIR) model, to provide evidence for preparedness and response to the epidemic. Classical SIR model was used to model the epidemic. Malthusian exponential decline method was employed to estimate the infective coefficient β for interventions. The initial value of parameters was determined based on empirical data. The modeling was implemented using Matlab 7.1 software. Without interventions, the outbreak was expected to experience three phrases: (1)early stage (the first 5 days) in which the epidemic developed slowly and could be intervened easily; (2) rapid growing stage (6-15 days) in which the number of infected cases increased quickly and the epidemic could not be well controlled;and (3) medium and late stage (16 days and later) in which more than 90% of the susceptible persons were infected but the intervention measures failed to prevent the epidemic. With the implementation of interventions, the epidemic was predicted to be controlled in the early stage, under the SIR model. The simulation based on the SIR model kept an acceptable consistency with the actual development of epidemic after the implementation of intervention measures. The SIR model seemed effective in modeling interventions to the epidemic of acute hemorrhagic conjunctivitis in the schools.
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<p><b>OBJECTIVE</b>To realize the influence of climatic changes on the transmission of hemorrhagic fever with renal syndrome (HFRS), and to explore the adoption of climatic factors in warning HFRS.</p><p><b>METHODS</b>A total of 2171 cases of HFRS and the synchronous climatic data in Changsha from 2000 to 2009 were collected to a climate-based forecasting model for HFRS transmission. The Cochran-Armitage trend test was employed to explore the variation trend of the annual incidence of HFRS. Cross-correlations analysis was then adopted to assess the time-lag period between the climatic factors, including monthly average temperature, relative humidity, rainfall and Multivariate Elño-Southern Oscillation Index (MEI) and the monthly HFRS cases. Finally the time-series Poisson regression model was constructed to analyze the influence of different climatic factors on the HFRS transmission.</p><p><b>RESULTS</b>The annual incidence of HFRS in Changsha between 2000 - 2009 was 13.09/100 000 (755 cases), 9.92/100 000 (578 cases), 5.02/100 000 (294 cases), 2.55/100 000 (150 cases), 1.13/100 000 (67 cases), 1.16/100 000 (70 cases), 0.95/100 000 (58 cases), 1.40/100 000 (87 cases), 0.75/100 000 (47 cases) and 1.02/100 000 (65 cases), respectively. The incidence showed a decline during these years (Z = -5.78, P < 0.01). The results of Poisson regression model indicated that the monthly average temperature (18.00°C, r = 0.26, P < 0.01, 1-month lag period; IRR = 1.02, 95%CI: 1.00 - 1.03, P < 0.01), relative humidity (75.50%, r = 0.62, P < 0.01, 3-month lag period; IRR = 1.03, 95%CI: 1.02 - 1.04, P < 0.01), rainfall (112.40 mm, r = 0.25, P < 0.01, 6-month lag period; IRR = 1.01, 95CI: 1.01 - 1.02, P = 0.02), and MEI (r = 0.31, P < 0.01, 3-month lag period; IRR = 0.77, 95CI: 0.67 - 0.88, P < 0.01) were closely associated with monthly HFRS cases (18.10 cases).</p><p><b>CONCLUSION</b>Climate factors significantly influence the incidence of HFRS. If the influence of variable-autocorrelation, seasonality, and long-term trend were controlled, the accuracy of forecasting by the time-series Poisson regression model in Changsha would be comparatively high, and we could forecast the incidence of HFRS in advance.</p>
Subject(s)
Humans , China , Epidemiology , Climate Change , Forecasting , Hemorrhagic Fever with Renal Syndrome , Epidemiology , Humidity , Incidence , Models, Theoretical , Seasons , TemperatureABSTRACT
Objective To analyze the spatio-temporal process on 2009 influenza A (HlNl) pandemic in Changsha and the influencing factors during the diffusion process. Methods Data were from the following 5 sources, influenza A (HlNl) pandemic gathered in 2009, Geographic Information System (GIS) of Changsha, the broad range of theorems and techniques of hot spot analysis, spatio-temporal process analysis and Spearman correlation analysis. Results Hot spot areas appeared to be more in the economically developed areas, such as cities and townships. The cluster of spatial-temporal distribution of influenza A (HlNl) pandemic was most likely appearing in Liuyang city (RR=22.70,P<0.01). The secondary cluster would include districts as Yuelu (RR=6A9,P< 0.01) , Yuhua (RR=81.63, P<0.01). Xingsha township appeared as the center in the Changsha county (RR=2.90, P<0.01) while townships as Yutangping (RR=19.31, P<0.01) , Chengjiao (RR=73.14,P<0.01) and Longtian appeared as the center in the west of Ningxiang county (RR= 14.43,P<0.01) and Wushan as the center in the Wangcheng county (RR= 13.84,P<0.01). As time went on, the epidemic moved towards the eastern and more developed regions. Regarding factor analysis, population, the amount of students, geographic relationship and business activities etc. appeared to be the key elements influencing the transmission of influenza A (H1N1) pandemic. At the beginning of the epidemic, population density served as the main factor (r=0.477, P<0.05) but during the initial and fast growing stages, it was replaced by the size of students to serve as the important indicator (r=0.831, P<0.01; r=0.518, P<0.01). However, during the peak of the epidemics, the business activities played an important role (r=-0.676, P<0.01). Conclusion Groups under high risk and districts with high incidence rates were shifting, along with the temporal process of influenza A(H1N1) pandemic, suggesting that the protection measures need to be adjusted, according to the significance of influencing factors at different stages.
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Objective To determine the incidence of non-fatal injuries and related influencing factors among children under 5 years old in China. Methods Data involving 10 819 children under 5 years old was from the Fourth National Health Service Survey of China. Injury-related indicators include: history of ever having had an injury, its frequency, cause, location and severity of the injury.A two-level Poissun regression was used to examine the significance of related socio-economic variables. Results The overall incidence rate of nonfatal injuries among children under 5 years old was 16.0 per 1000 population in the prior 12 months. The first three leading causes of non-fatal injuries were falls,animal bite, fire/bum among children under 1 year old,with the rates as 3.9, 1.8 and 1.8 per 1000 population, respectively. For children aged I to 4 years old, the first three leading causes were animal bite, fall, fire/burn with rates as 6.5,6.0 and 2.9 per 1000 population, respectively. 83.0% and 69.0% of last injuries occurred at home for the above said two age groups. No disability was found among children younger than 1 year old who suffered from a nonfatal injury while for the 1-4 age group, the disability accounted for 1.0% of injury-induced outcomes. After adjusting other variables,boys had 1.57 times the risk of injury compared with girls in the 1-4 age group (P＜0.05). The differences on the effects regarding ethmicity,per capita household income, and place were insignificant (P＞0.05). None of the socio-economic variables was found that significantly related to the non-fatal injury risk among children under 1 year old (P＞0.05). Conclusion The incidence of nonfatal injuries among children under 5 years old was 16.0 per 1000 population in the prior 12 months. The three leading causes of injuries were animal bite, falls, fire/bum respectively. Home was the most common place that non-fatal injuries occurred. Boys had a higher risk of injury compared with girls among children aged 1 to 4 years old and the difference was significant.