Communicable Disease Control ; methods ; trends

Objective: To optimize the warning threshold values of common communicable diseases in Gansu province, and improve the early warning effect. Method: An early warning model was set up for influenza, scarlet fever, other infectious diarrheal diseases, dysentery, typhoid and paratyphoid, viral hepatitis type E and hand foot and mouth disease (HFMD) respectively in Gansu by using the moving percentile method and cumulative sum method. By calculating the sensitivity, specificity, predictive value of positive test, predictive value of negative test, Youden' index and receiver-operating characteristic curve, the optimum early warning threshold values for communicable diseases in Gansu were selected. Results: The optimum early warning boundary values of influenza, scarlet fever, other infectious diarrheal diseases, dysentery, typhoid and paratyphoid, and viral hepatitis type E were P(90), P(80), P(95), P(90), P(80) and P(90) respectively. The optimum early warning parameters of HFMD were k=1.2, H=5σ. Under the optimum early warning boundary values/parameters, the early warning sensitivities of influenza, scarlet fever, other infectious diarrheal diseases, dysentery, typhoid and paratyphoid, viral hepatitis type E and HFMD were 86.67%, 100.00%, 91.67%, 100.00%, 100.00%, 100.00% and 100.00%, the specificities were 86.49%, 62.22%, 75.00%, 100.00%, 97.92%, 89.13% and 74.47%. The predictive values of positive test were 72.22%, 29.17%, 52.38%, 100.00%, 80.00%, 54.55% and 29.41%, and the predictive values of negative test were 94.12%, 100.00%, 96.77%, 100.00%, 100.00%, 100.00% and 100.00%, and the Youden' indexes were 0.73, 0.62, 0.67, 1.00, 0.98,0.89 and 0.74. Receiver-operating characteristic curve showed that the values/parameters of this warning boundary were the points closest to the upper left of the coordinate diagram. Conclusion: The early warning thresholds of influenza, other infectious diarrheal diseases, dysentery and hepatitis E in Gansu may be raised appropriately and the early warning parameters of HFMD need to be adjusted to improve the effectiveness of early warning.
China ; Communicable Disease Control/methods* ; Communicable Diseases/epidemiology* ; Disease Notification ; Disease Outbreaks/prevention & control* ; Humans ; Models, Theoretical ; Population Surveillance/methods*

Communicable Disease Control ; Communicable Diseases ; Disease Notification ; Humans ; Population Surveillance ; methods

OBJECTIVETo investigate the application of prospective space-time scan statistic in the early stage of detecting infectious disease outbreaks.

METHODSThe prospective space-time scan statistic was tested by mimicking daily prospective analyses of bacillary dysentery data of Chengdu city in 2005 (3212 cases in 102 towns and villages). And the results were compared with that of purely temporal scan statistic.

RESULTSThe prospective space-time scan statistic could give specific messages both in spatial and temporal. The results of June indicated that the prospective space-time scan statistic could timely detect the outbreaks that started from the local site, and the early warning message was powerful (P = 0.007). When the merely temporal scan statistic for detecting the outbreak was sent two days later, and the signal was less powerful (P = 0.039).

CONCLUSIONThe prospective space-time scan statistic could make full use of the spatial and temporal information in infectious disease data and could timely and effectively detect the outbreaks that start from the local sites. The prospective space-time scan statistic could be an important tool for local and national CDC to set up early detection surveillance systems.

China ; Communicable Disease Control ; methods ; Communicable Diseases ; epidemiology ; Humans ; Models, Statistical ; Population Surveillance ; methods ; Prospective Studies

OBJECTIVEforecast the epidemic trend and to evaluate the effect of outbreak control measures by investigation of a varicella outbreak event with a discrete time delay SEIR model.

METHODSA discrete time delay model was formulated by discretization method based on a continuous SEIR model with the consideration of the time delay effect on latent period and communicable period. The epidemic trend forecast was carried out based on the number of expected cases. The theoretical effect evaluation was assessed by comparing the results from different emergency control measures.

RESULTSWithout any control measures, the theoretical attack rate was 30.16% (504/1671). The course of the epidemic lasted for 4 months and the peak epidemic time was 78 days after the onset of the first case. 'Generation' phenomenon had been observed in the course of the epidemic with the interval of two weeks. The actual number of cases was decreased by 89.48% (451/504) compared with the number of expected cases under no control measure scenario. With the rigorous quarantine measure for all cases on their onset day, when the measure was conducted on 0, 14, 28, 42 days after the onset of the first case, the total numbers of expected cases were 22, 59, 127 and 220 respectively. With the quarantine measure conducted on 14 days after the onset of the first case, when the proportion of quarantine was 30%, 50%, 70%, 90%, the total number of expected cases were 485, 457, 386 and 169, respectively. With the emergent vaccination for all persons, when the measure was conducted on 0, 14, 28, 42 days after the onset of the first case, the total numbers of expected cases were 7, 26, 81 and 202 respectively. With the emergent vaccination conducted on 14 days after the onset of the first case, when the immunization coverage rate was 30%, 50%, 70%, 90%, the total numbers of expected cases were 354, 246, 127 and 40, respectively.

CONCLUSIONThe number of expected cases can be regarded as the reference to evaluate the effect of control measures. The simulation results suggest that it will get more benefits to conduct control measures earlier in varicella outbreak events, and the effect of emergent vaccination is better than that of quarantine measure under the same conditions.

Chickenpox ; epidemiology ; prevention & control ; Communicable Disease Control ; methods ; Disease Outbreaks ; prevention & control ; Humans ; Incidence ; Models, Theoretical

China ; epidemiology ; Communicable Disease Control ; methods ; Communicable Diseases ; epidemiology ; Disasters ; Humans

China ; epidemiology ; Communicable Disease Control ; methods ; organization & administration ; Communicable Diseases ; epidemiology ; Disease Outbreaks ; prevention & control ; Environmental Monitoring ; methods ; Epidemiologic Methods ; Epidemiological Monitoring ; Humans ; Risk Assessment ; methods ; Risk Factors

The world has paid a heavy price for the pandemic of the emerging respiratory communicable disease, so more concern about communicable disease surveillance and early warning has been aroused. This paper briefly reviews the establishment of the surveillance and early warning system of respiratory communicable diseases in China, discusses its future development and introduces the novel surveillance methods and early warning models for the purpose of establishment of a multi-channel surveillance and multi-dimensional early warning system of communicable diseases in the future and the improvement of the prevention and control of emerging respiratory communicable diseases in China.
Humans ; Population Surveillance/methods* ; Communicable Diseases/epidemiology* ; Communicable Diseases, Emerging/prevention & control* ; China/epidemiology* ; Pandemics ; Disease Outbreaks/prevention & control*

OBJECTIVETo select the premium alert threshold for major communicable disease by using the control graph alert technique based on the local disease information.

METHOD8 major communicable diseases in Songjiang district were ascertained by analysis of the national early warning detection information system which include the other diarrhea, mumps, chickenpox, scarlet fever, rubella, hand foot mouth disease, influenza and dysentery; weekly reported cases from 2008 to 2011 were used to establish the early detection model (PERCENTILE (array, x), array (4×5), x = 0.05, 0.10…0.95) by moving percentile method, next applying the established early detection model and the golden standard (AKX(-)D ± 2s) to predict the expected weekly cases in 2012 respectively, and then ascertain the predict results by comparison with the actual weekly cases in 2012 respectively, finally the premium threshold was selected by comparison of the model predicted results with the golden standard predicted results after comprehensive consideration of the sensitivity, specificity, positive predictive value and negative predictive value and receiver operating characteristic (ROC) curve.

RESULTSThe premium alert threshold for mumps, other diarrhea and rubella was P90, dysentery was P75, scarlet fever and chickenpox was P80, and the premium threshold for hand-foot-mouth disease (HFMD) and influenza was P95, the sensitivity of 8 major communicable diseases were 100%, 100%, 86%, 100%, 100%, 100%, 94%, 100%, respectively; the specificities were 92%, 73%, 72%, 77%, 73%, 92%, 66%, 80%, respectively; the positive predictive values were 43%, 40%, 32%, 8%, 24%, 20%, 59%, 47%, respectively; and the negative predictive values were 100%, 100%, 97%, 100%, 100%, 100%, 96%, 100%, respectively. The national recommended alert thresholds for the 8 major communicable diseases were P80, except for chickenpox (P50) and HFMD (CUSUM).

CONCLUSION6 out of 8 major communicable diseases' early detection thresholds in Songjiang district should be adjusted according to the analysis results. Premium alert threshold selection need to consider the local disease report and the characteristics of infectious diseases to upgrade the early detection capability.

China ; epidemiology ; Communicable Disease Control ; methods ; Communicable Diseases ; epidemiology ; Disease Notification ; Disease Outbreaks ; prevention & control ; Humans ; Models, Theoretical ; Population Surveillance ; methods

OBJECTIVETo explore the effect of new model for tuberculosis (TB) control and management, and provide a scientific basis and justification for making TB control strategies in rural communities.

METHODSAmong those townships with low TB service accessibility by the county TB control institute in Guangxi Xingye county (population of 679 thousands), four townships with total population of 152 518 and inconvenient transportation, were selected as the experimental group to conduct a new model research project.Based on the accessibility for community services, setting diagnosis and treatment management centers in township hospitals, employing family treatment supporters to supervise the treatment process. The TB cases of the base-line and the project expiration of the experimental group were 44 and 117. Meanwhile, three townships including Dapingshan, Longan and Gaofeng in the county with the similar condition and total population of 133 303 were selected as the control group. The control group conducted the provisions of national TB control program in the county TB clinic management. The TB cases of the base-line and the project expiration of the control group were 56 and 110. By double-direction comparison method, the effect of the new model was evaluated through TB patients detection, treatment outcomes and TB control management data. SPSS 13.0 statistical software was adopted and Chi-square test was used for analyzing technical data.

RESULTSAfter two-year project research implementation, in the experimental group the detection rate of new smear-positive TB patients increased from 16.39/100 000 (25/152 518) to 51.14/100 000 (78/152 518) (χ(2) = 27.281, P < 0.01), the cure rate of new smear-positive cases increased from 71.4% (15/21)to 91.1% (51/56) (χ(2) = 4.812, P < 0.05), and the completing treatment rate in newly diagnosed smear-negative cases improved from 23.5% (4/17)to 71.4% (15/21) (χ(2) = 8.622, P < 0.01); the loss rate of newly diagnosed smear-positive cases dropped from 23.8% (5/21) to 0.0% (0/56) (χ(2) = 10.608, P < 0.01), and the loss rate of newly diagnosed smear-negative cases decreased from 64.7% (11/17) to 4.8% (1/21) (χ(2) = 15.624, P < 0.01). Meanwhile, the cure rate of new smear-positive cases in the experimental group, 91.1% (51/56), was higher than the control group, 72.0% (36/50) (χ(2) = 6.531, P < 0.05). The loss rate of newly diagnosed smear-positive cases in the experimental group (0.0% (0/56)) was lower than the control group (16.0% (8/50)) (χ(2) = 7.534, P < 0.01). During the project implementation, in the experimental group the on time rate of taking medicine, 91.5% (107/117) and receiving medicine, 100.0% (117/117), the reexamining sputum ratio, 83.6% (98/117) were higher than that in the control group: 81.8% (90/110), 92.7% (102/110) and 64.5% (71/110). The differences were statistically significant (χ(2) = 4.589, 8.820 and 11.005, P < 0.05).

CONCLUSIONThe new management model had been proved effective. It can improve TB case detection and cure rates, reduce the loss rate of patients, and improve patient treatment and management conditions as well.

China ; Communicable Disease Control ; methods ; Humans ; Outcome Assessment (Health Care) ; Rural Health ; Tuberculosis ; prevention & control