Transmission dynamics and risk factors for pandemic H1N1‐related illness: outbreak investigation in a rural community of British Columbia, Canada

Influenza and Other Respiratory Viruses

Naveed Z. Janjua⁵  Danuta M. Skowronski⁵  Travis S. Hottes⁵  William Osei¹  Evan Adams³  Martin Petric⁵  Marcus Lem⁴  Patrick Tang⁵  Gaston De Serres²  David M. Patrick⁵ 

[1] Northern Health Authority, Prince George, BC, Canada;Institut National de santé publique du Québec, Québec, QC, Canada;British Columbia Ministry of Health, Victoria, BC, Canada;First Nations and Inuit Health, Health Canada, Vancouver, BC, Canada;BC Centre for Disease Control, Vancouver, BC, Canada

关键词: Aboriginal;    human influenza;    H1N1 pandemic;    risk factors;    serial interval;    transmission;   

DOI  :  10.1111/j.1750-2659.2012.00344.x

来源: Wiley

【 摘 要 】

Abstract

Please cite this paper as: Janjua et al. (2012) Transmission dynamics and risk factors for pandemic H1N1-related illness: outbreak investigation in a rural community of British Columbia, Canada. Influenza and Other Respiratory Viruses 6(3), e54–e62.

Objective  To characterize the first-wave epidemiologic features of influenza-like illness (ILI) associated with the novel pandemic A/H1N1 [A(H1N1)pdm09] virus.

Methods  We used generalized linear mixed models (GLMM) to assess risk factors and non-parametric and/or parametric distributions to estimate attack rates, secondary attack rates (SAR), duration of illness, and serial interval during a laboratory-confirmed community outbreak of A(H1N1)pdm09 clustered around on-reserve residents and households of an elementary school in rural British Columbia, Canada, in late April/early May 2009. ILI details were collected as part of outbreak investigation by community telephone survey in early June 2009.

Results  Overall, 92/408 (23%) of participants developed ILI and 36/408 (9%) experienced medically attended ILI (MAILI). The overall SAR in households was 22%: highest among participants 1–4 years of age (yoa) (50%) followed by <1 yoa (38%), 5–8 yoa (20%), 10–19 yoa (13%), 20–49 yoa (20%), and 50–64 yoa (0%). The median serial interval was estimated at 3·5 days (95% CI: 2·1–5·1). In multivariable GLMM analysis, having a chronic condition (OR: 2·58; 95% CI: 1·1–6·04), younger age [1–8 yoa: OR: 4·63; 95% CI: 2·25–9·52; 9–19 yoa: OR: 1·95; 95% CI: 0·97–3·9 (referent: ≥20 yoa)] and receipt of 2008–2009 influenza vaccine (OR: 2·68; 95% CI: 1·37–5·25) were associated with increased risk of ILI. Median duration of illness was 9 days, longer among those with chronic conditions (21 days). Median time to seeking care after developing illness was 4·5 days. On-reserve participants had higher chronic conditions, household density, ILI, MAILI, and SAR.

Conclusions  During a community outbreak of A(H1N1)pdm09-related illness, we identified substantial clinical ILI attack rates exceeding 20% with secondary household attack rates as high as 50% in young children. The serial interval was short suggesting a narrow period to prevent transmission.

【 授权许可】

Unknown   
© 2012 Blackwell Publishing Ltd