Ng Victoria, Tang Patrick, Jamieson Frances, Guyard Cyril, Low Donald E, Fisman David N
Child Health Evaluative Sciences, Research Institute of the Hospital for Sick Children, Toronto, Canada.
BMC Infect Dis. 2009 May 21;9:68. doi: 10.1186/1471-2334-9-68.
Legionellosis is a common cause of severe community acquired pneumonia and respiratory disease outbreaks. The Ontario Public Health Laboratory (OPHL) has conducted most testing for Legionella species in the Canadian province of Ontario since 1978, and represents a multi-decade repository of population-based data on legionellosis epidemiology. We sought to provide a laboratory-based review of the epidemiology of legionellosis in Ontario over the past 3 decades, with a focus on changing rates of disease and species associated with legionellosis during that time period.
We analyzed cases that were submitted and tested positive for legionellosis from 1978 to 2006 using Poisson regression models incorporating temporal, spatial, and demographic covariates. Predictors of infection with culture-confirmed L. pneumophila serogroup 1 (LP1) were evaluated with logistic regression models.
1,401 cases of legionellosis tested positive from 1978 to 2006. As in other studies, we found a late summer to early autumn seasonality in disease occurrence with disease risk increasing with age and in males. In contrast to other studies, we found a decreasing trend in cases in the recent decade (IRR 0.93, 95% CI 0.91 to 0.95, P-value = 0.001); only 66% of culture-confirmed isolates were found to be LP1.
Despite similarities with disease epidemiology in other regions, legionellosis appears to have declined in the past decade in Ontario, in contrast to trends observed in the United States and parts of Europe. Furthermore, a different range of Legionella species is responsible for illness, suggesting a distinctive legionellosis epidemiology in this North American region.
军团病是严重社区获得性肺炎和呼吸道疾病暴发的常见病因。自1978年以来，安大略省公共卫生实验室（OPHL）对加拿大安大略省的军团菌进行了大部分检测，并且是基于人群的军团病流行病学数十年数据的储存库。我们试图对安大略省过去30年军团病的流行病学进行基于实验室的回顾，重点关注该时间段内疾病发生率的变化以及与军团病相关的菌种。
我们使用纳入时间、空间和人口统计学协变量的泊松回归模型，分析了1978年至2006年提交并检测出军团病呈阳性的病例。使用逻辑回归模型评估培养确诊的嗜肺军团菌血清型1（LP1）感染的预测因素。
1978年至2006年，1401例军团病检测呈阳性。与其他研究一样，我们发现疾病发生存在夏末至秋初的季节性，疾病风险随年龄增长和男性增加。与其他研究不同的是，我们发现近十年来病例呈下降趋势（发病率比0.93，95%置信区间0.91至0.95，P值=0.001）；仅66%的培养确诊分离株被发现为LP1。
尽管与其他地区的疾病流行病学有相似之处，但与美国和欧洲部分地区观察到的趋势相反，安大略省的军团病在过去十年中似乎有所下降。此外，导致疾病的军团菌种范围不同，表明该北美地区存在独特的军团病流行病学。
