| BackgroundTuberculosis(TB) is an ancient disease which had been deemed as "human killer" and "white plague" in the17th century and the19th century, It is a chronic respiratory infectious diseases caused by lung infection of Mycobacterium tuberculosis. The main source of infection is the patients with tuberculosis bacteria spreading with respiratory tract. World Health Organization statistical results showed that total about800-1000million new tuberculosis occurred in the world every year and about300million people among them were died due to tuberculosis, and the youths and the adults are the main infected population in the300million people, also this disease caused the highest death in all infectious disease. Our country is one of the high TB burden countries and the total number of TB patients ranking second in the world. In the network of reported infectious diseases of our country the incidence and deaths of TB are always the first among class A and B infectious diseases, among these incidence people2/3are15to54-year old who has strongest production capacity, so this disease is a major public health problem in our country. Hunan Province’s smear-positive tuberculosis incidence is59/100000in2004, significantly higher than the national average incidence (46/100000), and the average annual tuberculosis in whole province is94.5/100000from2005to2011, which makes it, is the higher incidence of tuberculosis.Because of the seasonal distribution, some external sentimental factors including meteorological factors play an important role in the incidence and spread of TB. Some studies suggest that meteorological factors, such as temperature, precipitation, air pressure, etc, may be have impact on the incidence and the spread of TB. However, due to the differences in natural environment, ecological characteristics, climate, immunity and some other social factors, different studies have different results in how meteorological affect TB, or even come to opposite conclusion.Objectives In order to clear the development trends and spatial distribution of TB in Hunan Province, Epidemic monitoring data of Hunan Province obtained from the epidemic report system of CDC has been used and studied. At the same time, the TB monitoring data and meteorological data in three cities (Zhangjiajie, Changsha, and Shaoyang) which have different incidence trends were collected and analyzed to explore the impact of climate to TB and provide reference for future research.MethodsCollect the TB monitoring data in Hunan Province (2005-2011) to establish the TB epidemic monitoring database of Hunan Province, access to digital maps of Hunan Province. Surveillance data of TB and meteorological factors in Zhangjiajie, Changsha, and Shaoyang (2005-2011) was obtained. Descriptive analysis, time-series analysis, correlation analysis, and principal component regression were used to process data. Soft wares used in this study included SPSS17.0, SAS9.1, and ArcGIS9.2.Results1. About420,864cases of TB have been reported from2005to2011in Hunan Province with an annual incidence rate of94.5/100,000. There were TB cases every week; the incidence distribution is mainly concentrated in spring and summer, decline in autumn and winter, and lowest in winter. From time point view, the incidence of TB has obvious seasonal. In addition, the14cities in Hunan province can be divided into three incidence trend. Zhangjiajie, Yueyang, Yiyang, Huaihua, Loudi and Chenzhou showed decline trend; Changsha, Hengyang, Zhuzhou and Yongzhou belonged to increased and then decreased type; Shaoyang, Changde, Xiangtan, and Xiangxi showed a smooth change.2. The Kriging shows that the space distribution of TB incidence in Hunan Province decreases from northwestern to south, especially in Zhangjiajie; the incidence is the highest every year.3. According to the surveillance data of Hunan Province, using the method of time series analysis. ARIMA (1,1,1)12model was bullied. With this model to validate the data of2012, the results show that the model fit better. Used this model to predict the TB incidence in Hunan Province of2013, the results are (/10,0000):5.4329±1.7512(Jan);5.9535±1.9406(Feb);6.8320±1.9814(Mar);7.5719±1.9906(Apr);7.3021±1.9926(May);7.0457±1.9931(Jun);6.5958±1.9932(Jul);6.8486±1.9933(Aug);6.4918±1.9933(Sep);5.7884±1.9933(Oct);5.6756±1.9934(Nov);5.2179±1.9934(Dec).4. In the study, three representative cities (Zhangjiajie, Changsha, and Shaoyang) were chosen as the objects to explore the relationship between TB incidence and meteorological factors. The results show that the meteorological factors have lagged an effect on TB incidence. Moisture index, mean vapor pressure, average relative humidity, and mean temperature show a significant positive correlation to TB incidence; mean air pressure, day minimum pressure, day maximum pressure, mean wind velocity, and sunshine duration show a significant negative correlation.5. Principal component analysis showed that four main components were extracted, and the cumulative contribution rate was86.58%. The first component reflected the information about air pressure, temperature and vapor pressure; the second component reflected the wind speed and sunshine hours; the third component reflected the relative humidity, moisture index, and the fourth principal component reflected the three-week lagged moisture index. Regression analysis showed that the estimated coefficients of the fourth component was not significant and could not include in the regression model.Conclusions1. As whole the incidence of TB in Hunan province showed a downward trend, but different regions had different characteristics, they mainly as declined type which represented by Zhangjiajie city, increased and then decreased type which represented by Changsha city and stationary type which represented by Shaoyang city. The TB incidence showed a characteristic of obvious seasonal, spring and summer were the high season of TB and in winter the TB incidence reached lowest. In space, the TB incidence was serious in northwestern than southern in the whole province. 2. In climate factors the moisture index, mean vapor pressure, vapor pressure maximum, vapor pressure minimum, average relative humidity and mean temperature showed positive correlation with the TB incidence; the mean air pressure, pressure maximum, pressure maximum, mean wind velocity and sunshine duration showed negative correlation with the TB incidence.3. From the principle component regression model, the estimated coefficient about pressure, humidity, temperature, wind speed and sunshine hours could be included in the model, so they were the main meteorological factors to affect the TB incidence.Significance and innovation1. Analyzed the spatial and temporal distribution of the TB incidence in Hunan province, predicted the TB incidence by ARIMA mathematical model. Found the focus region which needs to be controlled and prevented, so provide a reference to allocate the health resources rationally.2. Analyzed the relationship between meteorological factors and TB incidence, and extracted the main factors to provide a reference to prevent and control TB. |
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