Centers for Disease Control and Prevention, Influenza Division, Atlanta, Georgia 30333, USA.
J Infect Dis. 2012 Sep 15;206(6):838-46. doi: 10.1093/infdis/jis467. Epub 2012 Jul 24.
Although influenza is a vaccine-preventable disease that annually causes substantial disease burden, data on virus activity in tropical countries are limited. We analyzed publicly available influenza data to better understand the global circulation of influenza viruses.
We reviewed open-source, laboratory-confirmed influenza surveillance data. For each country, we abstracted data on the percentage of samples testing positive for influenza each epidemiologic week from the annual number of samples testing positive for influenza. The start of influenza season was defined as the first week when the proportion of samples that tested positive remained above the annual mean. We assessed the relationship between percentage of samples testing positive and mean monthly temperature with use of regression models.
We identified data on laboratory-confirmed influenza virus infection from 85 countries. More than one influenza epidemic period per year was more common in tropical countries (41%) than in temperate countries (15%). Year-round activity (ie, influenza virus identified each week having ≥ 10 specimens submitted) occurred in 3 (7%) of 43 temperate, 1 (17%) of 6 subtropical, and 11 (37%) of 30 tropical countries with available data (P = .006). Percentage positivity was associated with low temperature (P = .001).
Annual influenza epidemics occur in consistent temporal patterns depending on climate.
虽然流感是一种可通过疫苗预防的疾病，每年都会造成巨大的疾病负担，但有关热带国家病毒活动的数据有限。我们分析了公开的流感数据，以更好地了解流感病毒的全球传播情况。
我们回顾了开源的、经实验室确认的流感监测数据。对于每个国家，我们从每年经实验室确认的流感阳性样本数量中提取出每个流行季节每周阳性样本百分比的数据。流感季节的开始定义为阳性样本比例持续高于年度平均值的第一周。我们使用回归模型评估阳性样本百分比与平均每月温度之间的关系。
我们从 85 个国家中确定了实验室确认的流感病毒感染数据。每年有一个以上流感流行期的情况在热带国家（41%）比在温带国家（15%）更为常见。在有数据的 43 个温带、6 个亚热带和 30 个热带国家中，有 3 个（7%）、1 个（17%）和 11 个（37%）国家全年都有活动（即每周至少有 10 个样本送检时可检出流感病毒）（P =.006）。阳性百分比与低温相关（P =.001）。
流感每年都会按照与气候一致的时间模式出现流行。
