Epidemiology and Surveillance, Tuberculosis and M/XDR-TB Programme, National Institute for Public Health and the Environment, Bilthoven, The Netherlands.
Int J Tuberc Lung Dis. 2012 May;16(5):639-44. doi: 10.5588/ijtld.11.0680. Epub 2012 Mar 9.
The seasonality of tuberculosis (TB) incidence suggests that the risk of infection or development of disease has a seasonal component.
To investigate factors associated with seasonal patterns of TB disease in the Netherlands by splitting notifications according to origin (natives vs. non-natives) and disease site (pulmonary TB [PTB] vs. extra-pulmonary TB [EPTB]). We focus on the presence of a seasonal peak, as much debate has centred on factors enhancing transmission vs. disease development.
Monthly notifications were derived from culture sample dates of all cases between 1993 and 2008. We fitted seasonal autoregressive integrated moving average (SARIMA) models to the time series. Seasonal decomposition revealed seasonal trends. To assess the seasonality of the peak, we repeated the analysis omitting December (trough) notifications.
TB notifications show a seasonal pattern, with a peak in spring and a trough in winter, which is present in both PTB and EPTB and in both natives and non-natives. However, when excluding December notifications, seasonality only holds in non-native EPTB and non-native TB notifications.
A seasonal peak in TB notifications (March-June) is apparent in non-natives, but is absent in natives. This peak is driven by the seasonality of EPTB notifications, which are highest in June-July. The contribution of winter crowding is discussed. Vitamin D deficiency, enhancing disease development at the end of winter-early spring, seems the most likely factor explaining the yearly peak in EPTB.
结核病（TB）发病率的季节性表明，感染或发病的风险具有季节性成分。
通过根据来源（本地人 vs. 非本地人）和疾病部位（肺结核[PTB] vs. 肺外结核[EPTB]）对通知进行拆分，研究与荷兰结核病发病季节性模式相关的因素。我们关注季节性高峰的存在，因为许多争论集中在增强传播的因素与疾病发展的因素上。
1993 年至 2008 年间所有病例的培养样本日期均来源于每月的通知。我们对时间序列拟合季节性自回归综合移动平均（SARIMA）模型。季节性分解揭示了季节性趋势。为了评估高峰的季节性，我们在分析中省略了 12 月（低谷）的通知。
TB 通知显示出季节性模式，春末夏初出现高峰，冬季出现低谷，这在 PTB 和 EPTB 以及本地人和非本地人中都存在。然而，当排除 12 月的通知时，季节性仅在非本地 EPTB 和非本地 TB 通知中存在。
非本地人中明显存在结核病通知（3 月至 6 月）的季节性高峰，但在本地人中不存在。这一高峰是由 EPTB 通知的季节性驱动的，EPTB 通知在 6 月至 7 月最高。讨论了冬季拥挤的影响。维生素 D 缺乏症，在冬末早春增强疾病的发展，似乎是解释 EPTB 每年高峰的最可能因素。
