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Objective To analyze the epidemiological characteristics of hepatitis B in Guangzhou from 2006 to 2018. Methods The data were retrieved from the National Infectious Disease Surveillance Information Report Management System. Descriptive methods were used to analyze and summarize the results. Chi-square test was used for statistical analysis of classification data, and Joinpoint software was used to analyze the annual change percentage and trend. Results A total of 292 674 cases of hepatitis B were reported in Guangzhou from 2006 to 2018, and the annual average reported incidence was 182.2 per 100,000. Chronic hepatitis B was the main type, accounting for 89.9%. The incidence rate of males (241.6 / 105) was higher than that of females (117.9 / 105), with a ratio of 2.0:1. During the period from 2006-2018, the reported incidence of hepatitis B in Guangzhou first increased, reached the highest in 2008, and then decreased year by year. There was no significant difference in the number of HBV cases among different months. The average onset age of hepatitis B reported in Guangzhou was 39.3 years old, and the average onset age increased year by year from 2006 to 2018. Conclusion The incidence rate of hepatitis B in Guangzhou has decreased since 2008, but it was still higher than the national average incidence rate. The hepatitis B infection in Guangzhou remains a big issue. It is suggested to further strengthen the prevention and control of hepatitis B in adults by maintaining a national immunization program for children, thereby reducing the epidemiological level of hepatitis B in Guangzhou.
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Objective@#To evaluate the burden and to describe the characteristics of spatial distribution caused by malignant tumors among different administrative areas in Guangzhou from 2010- 2013.@*Methods@#Based on data from the Cancer Registry system and population in Guangzhou in 2010- 2013, disability-adjusted life year (DALY) was assessed on the disease burden of cancer, in accordance with the method used in the Global Burden of Disease study.@*Results@#The crude incidence rates of cancer appeared as 256.22/105 in 2010-2011 and 270.04/105 in 2012-2013, with the crude mortality rates as 143.17/105 and 148.01/105, respectively, in Guangzhou. Cancers caused 606 238.95 DALYs in 2010-2011 and 623 763.80 DALYs in 2012-2013 for both sexes and 37.63 and 37.81 person year per 1 000 persons, with the standardized DALY rates as 34.51‰, 34.00‰ respectively. Three administrative districts (Yuexiu, Haizhu and Liwan) were with the largest disease burden of cancers that accounted for 45% of the DALYs for the whole Conghua district, with liver cancer was the leading cancer on DALYs, and tracheal, bronchus and lung cancer ranked the first in the other districts.@*Conclusions@#In Guangzhou, disease burden caused by cancers was both prominently seen in the newly developed urban area and the old districts. It remains an arduous task to continue programs on control and prevention of cancers in this city.
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Objective To understand the epidemiological and molecular characteristics of a norovirus-borne outbreak caused by GⅡ.4 Sydney 2012 in a university of Guangzhou to provide evidence for the prevention and control strategy on norovirus-caused epidemics.Methods A self-designed questionnaire was used to collect clinical information from the patients as well as other data related to the epidemic.Pathogen detections were performed through anal swab specimens from the patients,kitchen workers and samples from the environment.Positive samples were further sequenced for phylogenetic analysis.A case-control study was employed to identify the risk factors related to this outbreak.Results A total of 226 cases of norovirus-borne infection were identified between September 17 and 21,2017,including 223 students,with an attack rate of 0.73％ (223/30 711),and 3 kitchen workers.Students staying in the A dormitory area had the highest attack rate (1.73％,164/9 459).No clustering was found in different colleges or classes.Results from the case-control study revealed that people who ate at the canteen in A dormitory area during September 18 to 20 was at risk for the onset of illness (OR=10.75,95％CI:5.56-20.79).The highest risk was related to the dinner on September 18.Another significant risk factor (OR=3.65,95％ CI:1.92-6.94) was close personal contact in the same room of the dorm.The 3 norovirus infected kitchen workers were all from the canteen in A dormitory area where the positive rate of norovirus identified in kitchen workers was 26.67％ (12/45).Positive samples were sequenced and sub-typed with results showing that the GⅡ.4 Sydney 2012 variant and the nucleotide sequences of cases and kitchen workers were 100％ identical.Conclusions The outbreak was caused by norovirus GⅡ.4 Sydney 2012 variant at campus.Similar outbreaks had been seen since 2013,with the routes of transmission most likely due to food-borne or personal contact.
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Objective To investigate the infection pattern and etiological characteristics of a case of human infection with highly pathogenic avian influenza A (H7N9) virus and provide evidence for the prevention and control of human infection with highly pathogenic avian influenza virus.Methods Epidemiological investigation was conducted to explore the case's exposure history,infection route and disease progression.Samples collected from the patient,environments and poultry were tested by using real time reverse transcriptase-polymerase chain reaction (RT-PCR).Virus isolation,genome sequencing and phylogenetic analysis were conducted for positive samples.Results The case had no live poultry contact history,but had a history of pulled chicken processing without taking protection measure in an unventilated kitchen before the onset.Samples collected from the patient's lower respiratory tract,the remaining frozen chicken meat and the live poultry market were all influenza A (H7N9) virus positive.The isolated viruses from these positive samples were highly homogenous.An insertion which lead to the addition of multiple basic amino acid residues (PEVPKRKRTAR/GL) was found at the HA cleavage site,suggesting that this virus might be highly pathogenic.Conclusions Live poultry processing without protection measure is an important infection mode of "poultry to human" transmission of avian influenza viruses.Due to the limitation of protection measures in live poultry markets in Guangzhou,it is necessary to promote the standardized large scale poultry farming,the complete restriction of live poultry sales and centralized poultry slaughtering as well as ice fresh sale.
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Objective To study the willingness and influence factors related to "centralized slaughtering,fresh poultry listing and marketing" strategy,among the household chefs,and provide reference for government to adjust and optimize the strategy on avian influenza prevention.Methods According to the geographical characteristics and regional functions,6'monitoring stations' were selected from 12 residential districts of Guangzhou,respectively.Another 21 meat markets which selling live poultry,were selected in each station and 5 household chefs of each market were invited to attend a face to face interview.Basic information,personal cognitive,willingness and influencing factors to the policy were under study.Univariate and multivariate logistic regression methods were used.Results A total of 664 household chefs underwent the survey and results showed that the rate of support to the "centralized slaughtering,fresh poultry listing and marketing" strategy was 44.6％ (296/664).Results from the multi-factor logistic regression showed that those household chefs who were males (OR=1.618,95％ CI:1.156-2.264,P=0.005),having received higher education (OR=1.814,95％ CI:1.296-2.539,P=0.001),or believing that the existence of live poultry stalls was related to the transmission of avian influenza (OR=1.918,95％CI:1.341-2.743,P＜0.001) were factors at higher risk.These household chefs also intended to avoid the use of live poultry stalls (OR =1.666,95％CI:1.203-2.309,P=0.002) and accept the "centralized slaughtering,fresh poultry listing and marketing" strategy.Conclusion Detailed study on this subject and,setting up pilot project in some areas as well as prioritizing the education programs for household chefs seemed helpful to the implementation of the'freezing-fresh poultry'policy.
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Objective To understand the epidemiological and molecular characteristics of a norovirus-borne outbreak caused by GⅡ.4 Sydney 2012 in a university of Guangzhou to provide evidence for the prevention and control strategy on norovirus-caused epidemics.Methods A self-designed questionnaire was used to collect clinical information from the patients as well as other data related to the epidemic.Pathogen detections were performed through anal swab specimens from the patients,kitchen workers and samples from the environment.Positive samples were further sequenced for phylogenetic analysis.A case-control study was employed to identify the risk factors related to this outbreak.Results A total of 226 cases of norovirus-borne infection were identified between September 17 and 21,2017,including 223 students,with an attack rate of 0.73％ (223/30 711),and 3 kitchen workers.Students staying in the A dormitory area had the highest attack rate (1.73％,164/9 459).No clustering was found in different colleges or classes.Results from the case-control study revealed that people who ate at the canteen in A dormitory area during September 18 to 20 was at risk for the onset of illness (OR=10.75,95％CI:5.56-20.79).The highest risk was related to the dinner on September 18.Another significant risk factor (OR=3.65,95％ CI:1.92-6.94) was close personal contact in the same room of the dorm.The 3 norovirus infected kitchen workers were all from the canteen in A dormitory area where the positive rate of norovirus identified in kitchen workers was 26.67％ (12/45).Positive samples were sequenced and sub-typed with results showing that the GⅡ.4 Sydney 2012 variant and the nucleotide sequences of cases and kitchen workers were 100％ identical.Conclusions The outbreak was caused by norovirus GⅡ.4 Sydney 2012 variant at campus.Similar outbreaks had been seen since 2013,with the routes of transmission most likely due to food-borne or personal contact.
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Objective To investigate the infection pattern and etiological characteristics of a case of human infection with highly pathogenic avian influenza A (H7N9) virus and provide evidence for the prevention and control of human infection with highly pathogenic avian influenza virus.Methods Epidemiological investigation was conducted to explore the case's exposure history,infection route and disease progression.Samples collected from the patient,environments and poultry were tested by using real time reverse transcriptase-polymerase chain reaction (RT-PCR).Virus isolation,genome sequencing and phylogenetic analysis were conducted for positive samples.Results The case had no live poultry contact history,but had a history of pulled chicken processing without taking protection measure in an unventilated kitchen before the onset.Samples collected from the patient's lower respiratory tract,the remaining frozen chicken meat and the live poultry market were all influenza A (H7N9) virus positive.The isolated viruses from these positive samples were highly homogenous.An insertion which lead to the addition of multiple basic amino acid residues (PEVPKRKRTAR/GL) was found at the HA cleavage site,suggesting that this virus might be highly pathogenic.Conclusions Live poultry processing without protection measure is an important infection mode of "poultry to human" transmission of avian influenza viruses.Due to the limitation of protection measures in live poultry markets in Guangzhou,it is necessary to promote the standardized large scale poultry farming,the complete restriction of live poultry sales and centralized poultry slaughtering as well as ice fresh sale.
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Objective To study the willingness and influence factors related to "centralized slaughtering,fresh poultry listing and marketing" strategy,among the household chefs,and provide reference for government to adjust and optimize the strategy on avian influenza prevention.Methods According to the geographical characteristics and regional functions,6'monitoring stations' were selected from 12 residential districts of Guangzhou,respectively.Another 21 meat markets which selling live poultry,were selected in each station and 5 household chefs of each market were invited to attend a face to face interview.Basic information,personal cognitive,willingness and influencing factors to the policy were under study.Univariate and multivariate logistic regression methods were used.Results A total of 664 household chefs underwent the survey and results showed that the rate of support to the "centralized slaughtering,fresh poultry listing and marketing" strategy was 44.6％ (296/664).Results from the multi-factor logistic regression showed that those household chefs who were males (OR=1.618,95％ CI:1.156-2.264,P=0.005),having received higher education (OR=1.814,95％ CI:1.296-2.539,P=0.001),or believing that the existence of live poultry stalls was related to the transmission of avian influenza (OR=1.918,95％CI:1.341-2.743,P＜0.001) were factors at higher risk.These household chefs also intended to avoid the use of live poultry stalls (OR =1.666,95％CI:1.203-2.309,P=0.002) and accept the "centralized slaughtering,fresh poultry listing and marketing" strategy.Conclusion Detailed study on this subject and,setting up pilot project in some areas as well as prioritizing the education programs for household chefs seemed helpful to the implementation of the'freezing-fresh poultry'policy.
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Objective To investigate the molecular characteristics of dengue virus serotype 2 (DENV2) in Guangzhou during 2001-2015,and analyze the E gene of the strains isolated,the phylogenetic tree and molecular clock were constructed to know about the evolution of the strains.Methods The serum samples of the patients were detected by real time PCR,and positive samples were used to isolate dengue virus by using C6/36 cells.The E gene of the isolated strains were sequenced.The phylogenetic tree was constructed by using software Mega 4.0,and the molecular clock was drawn by using software BEASTv1.8.2.Results Twenty-six dengue virus strains were isolated between 2001 and 2015.They were all clustered into 2 genotypes,i.e.cosmopolitan genotype and Asian genotype Ⅰ.The strains isolated in Guangzhou shared high homology with Southeast Asian strains.The cosmopolitan genotype was divided into 2 sub-genotype at about 46 and 35 years ago.The substitution rate of dengue virus serotype 2 in Guangzhou was 7.1 × 10-4 per year per site.Conclusions There were close relationship between the Guangzhou strains and Southeast Asian strains.Guangzhou was at high risk of imported dengue fever,outbreak of dengue hemorrhagic fever and dengue shock syndrome.There might be two ways of introduction of cosmopolitan genotype.The substitution rate of the strains in Guangzhou was similar to that in the neighbor countries.
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Objective To evaluate the efficacy of a sustained releasing mosquito larvicide package against larval breeding and its impact on water and plant,in order to provide a scientific evidence for its application in control and prevention of Dengue.Methods Guangzhou Center for Disease Control and Prevention was chosen as the test place.Twenty test sites were set up,2 bags of sustained releasing larvicides package,1 bag of sustained releasing larvicides package,3 g 1％ temephos granules and nothing were put into 4 glass bottles for each test site from July to December in 2014,respectively.The 4 glass bottles were called high dose (H) group,low dose (L)group,positive control (P) group and blank control (B) group,respectively.The 4 groups were observed at intervals of 10 days for 19 times.Environmental air temperature,turbidity of water,number of larvae and damage of plant were recorded.And 5 test sites were selected to collect water specimen.The chemical oxygen demand,ammonia nitrogen concentration and temephos concentration of water specimen were detected.Results The larval breeding rates were 0 (0/380),1.1％ (4/380),0.8％ (3/380) and 63.4％ (241/380),damage rates of plant were 5.0％ (19/380),5.5％ (21/380),4.7％ (18/380),4.7％ (18/380) and turbidty rates of water were 24.5％ (93/380),19.7％ (75/380),33.4％ (127/380) and 20.3％ (77/380) in H,L,P and B groups,respectively.Statistically significant differences were seen in larval breeding rate and turbidity rate of water between different groups (x2 =823.565,24.715,all P ＜ 0.05),but they were not seen in damage rate of plant (x2 =0.332,P ＞ 0.05).The temephos concentrations were 1.24,0.78 and 2.33 mg/L in H,L and P groups,respectively.Statistically significant differences were seen in temephos concentration between different groups (H =35.426,P ＜ 0.01),but they were not seen in chemical oxygen demand and ammonia nitrogen concentration (H =0.239,0.013,all P ＞ 0.05).Conclusions The sustained releasing package of mosquito larvicide makes less pollution to water and has no impact on water turbidity.Moreover,it doesn't damage the aquatic plant.The efficacy of the sustained releasing package of mosquito larvicide could effectively prevent mosquito larval breeding in Dengue epidemic period.
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Objective To investigate the molecular characteristics of dengue virus serotype 2 (DENV2) in Guangzhou during 2001-2015,and analyze the E gene of the strains isolated,the phylogenetic tree and molecular clock were constructed to know about the evolution of the strains.Methods The serum samples of the patients were detected by real time PCR,and positive samples were used to isolate dengue virus by using C6/36 cells.The E gene of the isolated strains were sequenced.The phylogenetic tree was constructed by using software Mega 4.0,and the molecular clock was drawn by using software BEASTv1.8.2.Results Twenty-six dengue virus strains were isolated between 2001 and 2015.They were all clustered into 2 genotypes,i.e.cosmopolitan genotype and Asian genotype Ⅰ.The strains isolated in Guangzhou shared high homology with Southeast Asian strains.The cosmopolitan genotype was divided into 2 sub-genotype at about 46 and 35 years ago.The substitution rate of dengue virus serotype 2 in Guangzhou was 7.1 × 10-4 per year per site.Conclusions There were close relationship between the Guangzhou strains and Southeast Asian strains.Guangzhou was at high risk of imported dengue fever,outbreak of dengue hemorrhagic fever and dengue shock syndrome.There might be two ways of introduction of cosmopolitan genotype.The substitution rate of the strains in Guangzhou was similar to that in the neighbor countries.
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<p><b>OBJECTIVES</b>To investigate a survey about acceptance of central slaughtering of live poultry in residents of Guangzhou.</p><p><b>METHODS</b>We conducted a telephone survey by sampling residents with fixed-line telephone and with normal hearing, whose age is more than 15 years, by Mitofsky-Waksberg two-stage method during Jan 6(th) to 8(th), 2014. 358 residents finished the telephone questionnaire by 12 320 health hot line. We investigated the acceptance rate of city-wide central slaughtering permanently. We compared the difference between the respondents and the 2010 Guangzhou census data by Cohen's effect sizes (w) and weighted by population age and sex. We used χ(2) test to compare the acceptance rate of central slaughtering in residents with different characteristic. We used multiple logistic regression analysis to analyze the factors.</p><p><b>RESULTS</b>The difference in gender and age was small between respondents and the 2010 Guangzhou census data (w value was 0.13, 0.28, respectively), but that in education and marital status was large (w value was 0.52, 0.31, respectively). 49.0% (95% CI: 43.7%-54.3%) accept city-wide central slaughtering permanently. The acceptance rate of city-wide central slaughtering permanently in those who bought fresh, chilled and frozen poultry in their family in previous year was 54.3% (133/245), 60.0% (57/95) and 59.8% (49/82), respectively. It was more than those who didn't buy fresh, chilled and frozen poultry (38.1% (43/113), 44.9% (118/263) and 45.7% (126/276); χ(2) values were 8.15, 6.40 and 5.03; P values were 0.004, 0.011 and 0.025, respectively). The acceptance rate of city-wide central slaughtering permanently in those who deem fresh poultry taste better than live poultry was 64.9% (24/38). It more than those who deem not (47.0%, 151/320) (χ(2) = 4.22, 6.02, P = 0.040, 0.014, respectively). The acceptance rate of city-wide central slaughtering permanently in the male (OR = 2.68, 95% CI: 1.64-4.37) and those who deem getting sick due to buying live birds from LPM (OR = 1.72, 95% CI: 1.05-2.82), who can accept only fresh poultry carcass supply (OR = 2.39, 95% CI: 1.33-4.30), Who bought live poultry in their family in previous year (OR = 0.29, 95% CI: 0.11-0.74), who will decrease the consumption after ban on live poultry sale (OR = 0.50, 95% CI: 0.30-0.83) was 58.6% (109/186), 59.0% (92/156), 60.7% (139/230), 44.9% (132/295), 36.6% (68/186), respectively.</p><p><b>CONCLUSION</b>In the early stage of avian influenza A(H7N9) epidemic in Guangzhou, the rate of acceptance of central slaughtering permanently in residents was not so high. Who deem getting sick due to buying live birds from LPM, who could accept only fresh poultry carcass supply and the male more accept city-wide central slaughtering permanently.</p>
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Animals , Humans , Male , Attitude to Health , Birds , Epidemics , Influenza A Virus, H7N9 Subtype , Influenza in Birds , Influenza, Human , Meat-Packing Industry , Poultry , Surveys and QuestionnairesABSTRACT
<p><b>OBJECTIVE</b>To understand the threshold of Breteau Index (BI) on Dengue fever outbreak in Guangzhou.</p><p><b>METHODS</b>Dengue cases from Guangzhou during 2006 to 2012 in the National Infectious Disease Report and Management System were collected and described. Receiver-operating characteristic (ROC) curve was used to judge the threshold of BI on the outbreaks of Dengue fever.</p><p><b>RESULTS</b>A total of 1 038 local cases were reported from 2006 to 2012 in Guangzhou city, with a total of 71 outbreaks and 259 sporadic episodes. Data from the ROC curve analysis showed that the highest Youden index that BI predicting Dengue fever outbreaks or sporadic were 6.4 and 9.5, respectively. When using BI = 6.4 in predicting the sporadic case of Dengue, sensitivity and specificity were 67.8% , 79.1% , respectively. When using BI = 9.5 in predicting the outbreaks of Dengue, sensitivity and specificity were 81.7%, 90.9%, respectively.</p><p><b>CONCLUSION</b>Both BI = 5.0 and BI = 9.5 showed effects on predicting the nature of sporadic or outbreak on Dengue, suggesting that the threshold need to be monitored, according to the purpose of control and availability of manpower, in order to get better sensitivity and specificity.</p>
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Humans , China , Epidemiology , Dengue , Epidemiology , Disease Outbreaks , ROC Curve , Sensitivity and SpecificityABSTRACT
<p><b>OBJECTIVE</b>To analyze the results of nine-round environmental specimen surveillance programs in five live poultry markets pre-, during and post the 'closing days' and to evaluate the effects of 'closing days' on live poultry markets regarding the control against avian influenza pollution.</p><p><b>METHODS</b>In January 2014, control measures including culling poultry, completely cleaning and disinfecting and a 'three-day-closing' measure were conducted in five live poultry markets which were found positive for H7N9 nucleic acid in the 1(st) round environmental specimen surveillance program. Second surveillance program was conducted after a thorough disinfection campaign was launched. Several times surveillance were conducted in one week, after the markets were reopened. RT-PCR was used to test the nucleic acid of HA, H5, H7 and H9 viruses.</p><p><b>RESULTS</b>654 specimens from the environment were collected and tested. During the first round surveillance program, positive rates for influenza A and H5/H7/H9 nucleic acid of poultry stalls appeared to be 94.44% and 61.11% respectively. The positive rates of poultry stalls reduced to 0 after the disinfection campaign but increased again after the markets reopened. The positive rate for influenza A of poultry stalls slightly increased from 50.00% in the third surveillance to 72.22% in the ninth surveillance (P > 0.05). The positive rate for H5/H7/H9 of poultry stalls showed a significantly increasing trend, from 0 in the third surveillance to 44.44% in the ninth surveillance (P < 0.01). The positive rates for influenza A and H5/H7/H9 nucleic acid of specimens were 28.89% and 17.78% respectively. The positive rate of specimens reduced to 0 after disinfection while increased again after reopening of the markets. The positive rate for influenza A of specimens slightly increased from 19.67% in the third surveillance to 27.54% in the ninth surveillance programs (P > 0.05). The positive rate for H5/H7/H9 of specimen showed a significant increasing trend, from 0 in the third surveillance to 8.70% in the ninth-round surveillance programs (P < 0.01). The positive rate for influenza A was the highest for slaughter- related specimens of 22.4% (35/156). The positive rates for influenza A from sewage and drinking water being collected on the later stage after the markets reopened (25.9%, 12.4%)were higher than those on the early stage (8.3%, 8.6%) (P > 0.05). The positive rate for influenza A of poultry stalls with overnight poultry storage (91.7%) was significant higher than that of poultry stalls without the overnight storage (33.3%). The positive rate for influenza A of poultry stalls in which simultaneously selling different kinds of poultry (85.7%) was significant higher than that of poultry stalls in which selling only one kind of poultry at one time (25.0%) (P < 0.05).</p><p><b>CONCLUSION</b>Slaughter in live poultry markets posed a large risk of pollution diffusion. Sewage and drinking water showed an accumulation effect for avian influenza virus. Overnight poultry storage and selling different kinds of poultry at one time at the poultry stalls seemed the risk factors for avian influenza virus transmission. Complete cleaning, disinfecting and several 'closing days' for live poultry markets seemed effective in eliminating avian influenza virus. Once the markets were reopened, they seemed to be soon polluted again.</p>
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Animals , China , Commerce , Disinfection , Environmental Microbiology , Environmental Monitoring , Influenza A virus , Influenza in Birds , Poultry , VirologyABSTRACT
ObjectiveTo analyze the Envelope (E) gene of type 1,2,3 dengue virus isolated fromGuangzhouin2010, andtoinvestigatetheinfectionsourceandvirusgenotypes.MethodsEighty-five serum samples were collected from 85 patients in acute phase of dengue fever.Dengue virus was cultured and isolated by C6/36 cells.The whole length of E gene was amplified by reverse transcriptase-polymerase chain reaction (RT-PCR) and then sequenced.The phylogenetic tree was drawn by neighbor-joining method.The bioinformatics analysis was performed by combining the phylogenetic information and the epidemiologic data.ResultsSix strains of type 1 dengue virus,two strains of type 2 dengue virus and six strains of type 3 dengue virus were isolated from 85 samples.The E gene sequence of these strains was obtained by sequencing.The phylogenetic analysis showed that type 1 and 3 dengue virus belonged to two genotypes (Asian and South Pacific ocean,India subcontinent and Southeast Asia/South Pacific ocean,respectively),and type 2 dengue virus belonged to one genotype (Malaysia/India subcontinent).ConclusionIt's presumed that all strains of type 2 dengue virus are imported,four strains of type 1 dengue virus are imported and four strains of type 3 dengue virus arc imported,the remaining two stains of type 1 and two stains of type 3 dengue virus need mosquito intermediary research further to prove their origins.
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<p><b>OBJECTIVE</b>To document the investigation and control of an outbreak of gastroenteritis in City G, South China, and provide a reference for preventing future outbreaks.</p><p><b>METHODS</b>An ambispective cohort study was designed. Attack rate (AR) and relative risks (RR) were calculated to identify the causes of gastroenteritis. Investigations using questionnaires included personal interviews with patients and doctors, reviews of medical records, laboratory examinations of fecal specimens and continuous hygiene monitoring of water samples from the waterworks.</p><p><b>RESULTS</b>Overall, 427/71534 (AR=5.97%) cases were identified between October 31 and November 12 2010. Geographic distribution was highly localized, with 80% of cases occurring in the areas supplied by waterworks-A. Consumption of water provided solely by waterworks-A was found to be associated with illness (RR=8.20, 95 CI%:6.12-10.99) compared with that from waterworks-B. Microbiological analyses confirmed the presence of Norovirus in six of eight fecal samples from symptomatic patients, two water samples from waterworks-A and two sewage samples. After taking effective measures, the hygienic indices of waterworks-A met health criteria again on November 9 and no cases were reported 3 days later.</p><p><b>CONCLUSION</b>The outbreak reported here was caused by drinking tap water contaminated with sewage at the source. Early identification of possible contamination sources and awareness of changes that might negatively impact water quality are important preventive measures to protect public health.</p>
Subject(s)
Adolescent , Adult , Aged , Child , Child, Preschool , Female , Humans , Infant , Male , Middle Aged , Young Adult , Disease Outbreaks , Gastroenteritis , Epidemiology , Water PollutionABSTRACT
Objective To sequence and analyze the envelope (E) gene of type Ⅰ dengue virus isolated from Guangzhou in 2009 for tracing the infection source. Methods The serum samples were collected from patients diagnosed with dengue fever in Guangzhou area during 2009. Dengue virus was isolated and cultured in C6/36 cells.The whole length of E gene was amplified by reverse transcriptase-polymerase chain reaction (RT-PCR) and then sequenced. The phylogenetic tree was drawn by neighbor-joining method. The bioinformatics analysis was performed by combining the phylogenetic information and the epidemiology data. Results Four strains of type Ⅰ dengue virus were isolated from 19 samples. E gene of these strains was amplified and sequenced. The phylogenetic analysis showed that 09/GZ/9104 strain and 09/GZ/9236 strain had identical nucleotide sequence and fell within the American/African group, 09/GZ/11534 stain and 09/GZ/11562 strain had similar sequence homology and fell within the Asian group. Conclusion The typeⅠdengue viruses in Guangzhou area in 2009 are imported, which belong to two genotypes and may come from two independent origins respectively.