Time-series analysis of geographically specific monthly number of newly registered cases of active tuberculosis in Japan
Time-series analysis of geographically specific monthly number of newly registered cases of active tuberculosis in Japan
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DOI：
10.1371/journal.pone.0213856
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发表时间：
2019-03-18
期刊：
影响因子：
3.7
通讯作者：
Kobayashi, Nobumichi
中科院分区：
文献类型：
--
作者：
Sumi, Ayako;Kobayashi, Nobumichi
背景了解结核病（TB）流行的季节性可能有助于识别潜在的可改变的风险因素。在日本境外进行的研究发现，报告的结核病病例存在季节性变化，春季和夏季为高峰，秋季和冬季发病率较低。关于春季或夏季结核病流行高峰的一种假设是，由于室内拥挤和通风不良，冬季结核病传播可能会增加，而社会弱势群体在春季和夏季会出现原发性结核病。另一个合理的解释是，冬季维生素 D 缺乏会降低免疫力，增加这些季节结核病重新激活的风险。先前的研究表明，存在与纬度相关的因素，包括冬季阳光的减少及其对维生素 D 水平的影响。在这里，我们根据拥挤和纬度的影响，研究了日本结核病流行的季节性机制。方法我们使用由谱分析和最小二乘法组成的时间序列分析，分析了 1998 年至 2015 年日本所有 47 个都道府县每月新登记的各种形式活动性结核病病例数。结果在 47 个都道府县的所有功率谱密度中，在与1年为一个周期。这种季节性的程度与人口密度有关。我们没有在高纬度地区检测到更大的季节性，这表明纬度相关因素，包括冬季日照减少及其对维生素 D 水平的潜在影响，对日本的季节性没有显着影响。讨论和结论在人口密度高的地区，需要采取措施解决青少年和中年人中两种特定类型的主动感染风险：(i) 公共交通的使用，以及 (ii) 没有定期体检的非正规就业。为了控制活动性结核病流行，调查每个地区和每个年龄组活动性结核病时间模式的周期性结构非常重要。
BackgroundUnderstanding seasonality of tuberculosis (TB) epidemics may lead to identify potentially modifiable risk factors. Studies conducted outside Japan have found seasonal variation among reported TB cases, with peaks in spring and summer and low prevalence in fall and winter. One hypothesis regarding spring or summer peaks in TB epidemics is that TB transmission likely increases in winter because of indoor crowding and poor ventilation, with development of primary TB among socially vulnerable people in spring and summer. Another plausible explanation is that vitamin D deficiency in winter depresses immunity, increasing the TB reactivation risk in these seasons. Previous studies suggest latitude-dependent factors, including reduced winter sunlight and its effect on vitamin D levels. Here, we investigated mechanisms of seasonality in TB epidemics in Japan, according to the effects of crowding and latitude.MethodsWe used time-series analysis consisting of spectral analysis and least-squares method, to analyse geographically specific monthly number of newly registered cases of all forms of active TB in all 47 prefectures of Japan during 1998-2015.ResultsIn all power spectral densities for the 47 prefectures, spectral lines were observed at frequency positions corresponding to a 1-year cycle. The degree of this seasonality was associated with population density. We did not detect greater amplitude of seasonality at higher latitudes, suggesting that latitude-dependent factors, including reduced winter sunlight and its potential effect on vitamin D levels, do not contribute significantly to seasonality in Japan.Discussion and conclusionIn districts with high population density, measures are needed to address two specific types of active infection risk in adolescents and middle-aged adults: (i) public transport use, and (ii) irregular employment with no periodic medical examinations. To control active TB epidemics, investigating periodic structures in the temporal patterns of active TB in each district and each age group is important.