Clark Michael, Vynnycky Emilia
First Nations and Inuit Health Branch, Health Canada, Ottawa, Canada.
Int J Epidemiol. 2004 Jun;33(3):477-84. doi: 10.1093/ije/dyh001. Epub 2004 Mar 11.
Tuberculosis (TB) notification rates among First Nations people in British Columbia, Canada, are higher than those among non-First Nations people, although rates are declining more rapidly in the First Nations population. The epidemiology of tuberculous infection and disease during the period 1926-2000 in this population was investigated.
The trend in the annual risk of infection (ARI) since 1926 was estimated using tuberculous meningitis mortality statistics and skin testing data. Risks of progression from infection to disease were estimated by fitting model predictions of disease incidence to TB notifications, using maximum likelihood methods. Infectious TB notifications were matched with ARI estimates to obtain the number of transmissions per infectious case over time.
We estimate that the ARI decreased from more than 10% during the prechemotherapy era to less than 0.1% by 2000. The risks of primary, reactivation, and exogenous re-infection disease among adults aged 25-44 years were 22%, 0.1%, and 6%, respectively. The number of transmissions per infectious case decreased from 16 to 2 from the early 1970s to the late 1990s.
This study shows that the risk of infection among British Columbia First Nations people is decreasing, while the relative contribution of reactivation to disease incidence is increasing. Once infected, First Nations people may have a higher risk of developing disease than other populations.
在加拿大不列颠哥伦比亚省，原住民的结核病报告率高于非原住民，尽管原住民中的发病率下降得更快。本研究调查了该人群在1926年至2000年期间结核感染和疾病的流行病学情况。
利用结核性脑膜炎死亡率统计数据和皮肤试验数据估算自1926年以来的年度感染风险（ARI）趋势。通过使用最大似然法将疾病发病率的模型预测与结核病报告病例拟合，估算从感染发展为疾病的风险。将传染性结核病报告病例与ARI估算值相匹配，以获取每个传染性病例随时间推移的传播次数。
我们估计，ARI从化疗前时代的超过10%下降到2000年时的低于0.1%。25至44岁成年人中原发性、再激活和外源性再感染疾病的风险分别为22%、0.1%和6%。从20世纪70年代初到90年代末，每个传染性病例的传播次数从16次降至2次。
本研究表明，不列颠哥伦比亚省原住民的感染风险正在降低，而再激活对疾病发病率的相对贡献正在增加。一旦感染，原住民患疾病的风险可能高于其他人群。
