Enteric, Zoonotic and Vector-borne Diseases, Communicable Disease Prevention and Control, Public Health Ontario, Toronto, Ontario, Canada.
PLoS One. 2013 Sep 30;8(9):e76208. doi: 10.1371/journal.pone.0076208. eCollection 2013.
We examined malaria cases reported to Ontario's public health surveillance systems from 1990 through 2009 to determine how temporal scale (longitudinal, seasonal), spatial scale (provincial, health unit), and demography (gender, age) contribute to Plasmodium infection in Ontario travellers. Our retrospective study included 4,551 confirmed cases of imported malaria reported throughout Ontario, with additional analysis at the local health unit level (i.e., Ottawa, Peel, and Toronto). During the 20-year period, Plasmodium vivax accounted for 50.6% of all cases, P. falciparum (38.6%), Plasmodium sp. (6.0%), P. ovale (3.1%), and P. malariae (1.8%). During the first ten years of the study (1990-1999), P. vivax (64% of all cases) was the dominant agent, followed by P. falciparum (28%); however, during the second ten years (2000-2009) the situation reversed and P. falciparum (55%) dominated, followed by P. vivax (30%). The prevalence of P. falciparum and P. vivax cases varied spatially (e.g., P. falciparum more prevalent in Toronto, P. vivax more prevalent in Peel), temporally (e.g. P. falciparum incidence increased during the 20-year study), and demographically (e.g. preponderance of male cases). Infection rates per 100,000 international travellers were estimated: rates of infection were 2× higher in males compared to females; rates associated with travel to Africa were 37× higher compared to travel to Asia and 126× higher compared to travel to the Americas; rates of infection were 2.3-3.5× higher in June and July compared to October through March; and rates of infection were highest in those 65-69 years old. Where exposure country was reported, 71% of P. falciparum cases reported exposure in Ghana or Nigeria and 63% of P. vivax cases reported exposure in India. Our study provides insights toward improving pre-travel programs for Ontarians visiting malaria-endemic regions and underscores the changing epidemiology of imported malaria in the province.
我们考察了安大略省公共卫生监测系统在 1990 年至 2009 年报告的疟疾病例，以确定时间尺度（纵向、季节性）、空间尺度（省级、卫生单位）和人口统计学（性别、年龄）如何导致安大略省旅行者感染疟原虫。我们的回顾性研究包括整个安大略省报告的 4551 例确诊的输入性疟疾病例，并在当地卫生单位（即渥太华、皮尔和多伦多）进行了额外分析。在 20 年期间，间日疟原虫占所有病例的 50.6%，恶性疟原虫（38.6%），疟原虫属（6.0%），卵形疟原虫（3.1%）和间日疟原虫（1.8%）。在研究的前十年（1990-1999 年），间日疟原虫（所有病例的 64%）是主要病原体，其次是恶性疟原虫（28%）；然而，在接下来的十年（2000-2009 年），情况发生了逆转，恶性疟原虫（55%）占主导地位，其次是间日疟原虫（30%）。恶性疟原虫和间日疟原虫病例的流行情况在空间上（例如，恶性疟原虫在多伦多更为普遍，间日疟原虫在皮尔更为普遍）、时间上（例如，在 20 年的研究期间，恶性疟原虫的发病率增加）和人口统计学上（例如，男性病例居多）存在差异。每 10 万国际旅行者的感染率估计如下：男性感染率是女性的 2 倍；与前往亚洲相比，前往非洲的感染率高 37 倍，与前往美洲相比，感染率高 126 倍；与 10 月至 3 月相比，6 月和 7 月的感染率高 2.3-3.5 倍；65-69 岁的感染率最高。在报告了接触国的情况下，71%的恶性疟原虫病例报告在加纳或尼日利亚接触，63%的间日疟原虫病例报告在印度接触。我们的研究为改善前往疟疾流行地区的安大略省居民的旅行前规划提供了一些见解，并强调了该省输入性疟疾的流行病学变化。
