Epidemiology and Infection

Original Papers

Influenza

Probable longer incubation period for human infection with avian influenza A(H7N9) virus in Jiangsu Province, China, 2013

Y. HUANGa1a4 , K. XUa2 , D. F. RENa3a4 , J. AIa2 , H. JIa2, A. H. GEa2, C. J. BAOa2, G. Q. SHIa4, T. SHENa4, F. Y. TANGa2 c1, Y. F. ZHUa2 c1, M. H. ZHOUa2 and H. WANGa2

a1 Tongling Centre for Disease Control and Prevention, Tongling, Anhui, China

a2 Jiangsu Provincial Centre for Disease Control and Prevention, Nanjing, China

a3 Tongren Centre for Disease Control and Prevention, Tongren, Guizhou, China

a4 Chinese Field Epidemiology Training Programme, Chinese Centre for Disease Control and Prevention, Beijing, China

SUMMARY

Human infection with the emerging avian influenza A(H7N9) virus in China in 2013 has raised global concerns. We conducted a retrospective descriptive study of 27 confirmed human influenza A(H7N9) cases in Jiangsu Province, to elaborate poultry-related exposures and to provide a more precise estimate of the incubation periods of the illness. The median incubation period was 6 days (range 2–10 days) in cases with single known exposure and was 7·5 days (range 6·5–12·5 days) in cases with exposures on multiple days, difference between the two groups was not significant (Z = −1·895, P = 0·058). The overall median incubation period for all patients was estimated to be 7·5 days (range 2–12·5 days). Our findings further highlight the necessity for public health authorities to extend the period of medical surveillance from 7 days to 10 days.

(Received July 08 2013)

(Revised December 09 2013)

(Accepted January 24 2014)

(Online publication February 24 2014)

Key words

  • Avian flu;
  • emerging infections;
  • infectious disease epidemiology

Correspondence

c1 Author for correspondence: Dr Y. F. Zhu or Dr F. Y. Tang, Jiangsu Provincial Centre for Disease Control and Prevention, Nanjing, China. (Email: jszyf@jscdc.cn) [Y. F. Zhu] (Email: tfyepi@jscdc.cn) [F. Y. Tang]

Footnotes

  These authors contributed equally to this work.

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