[Investigation on a seasonal influenza accompanying with the first locale novel A/H1N1 influenza outbreak in China].
OBJECTIVE
To timely summarize past experience and to provide more pertinent reference for control and prevention in A/H1N1 cases in influenza season.


METHODS
During May 25 to 31, 2009, 2 secondary community cases caused by a influenza A/H1N1 imported case. In the close contacts of 3 A/H1N1 cases, 14 had some aspirator symptoms onset, such as fever (> or = 37.5 degrees C), cough, sore throat and etc. Laboratory tests excluded the infection of A/H1N1 influenza. For throat swab test for the 14 cases, 7 were tested for seasonal influenza virus. A face-to-face or telephone interview was conducted by CDC staff to collect information of 62 close contacts.


RESULTS
Of 14 fever cases, there was no significant by differences by age[15-age group: 19.2% (5/26), over 25-age group: 25.0% (9/36); chi(2) = 0.287, P = 0.592]; by sex group [24.0% (6/25) for male and 21.6% (8/37) for female; chi(2) = 0.048, P = 0.826], by working units [dressing and design, photograph, saleroom and others, consumer group: 42.1% (8/19), 27.3% (3/11), 12.5% (2/16) and 6.3% (1/16); chi(2) = 7.653, P = 0.054], by dormitory style [dormitory style = 33.3% (4/12), non-dormitory style = 29.4% (10/34); chi(2) = 0.699, P = 0.403]. All the cases had fever (37.5 - 37.9 degrees C), no case had diarrhea. One in 3 A/H1N1 cases had diarrhea. All the 14 cases were negative result for A/H1N1 RNA. Six from 7 cases were positive for seasonal influenza test.


CONCLUSIONS
This was a seasonal influenza outbreak happened in the close contacts of first confirmed A/H1N1 cases in community in mainland China. It showed that we should exclude the seasonal influenza in the investigation of A/H1N1 cases in the seasonal influenza period in some time. It is necessary to take effective measure to strengthen the control and prevention of seasonal influenza.
Guangzhou Center for Disease Control and Prevention, China.
Jun
J
Yuan
Mei-xia
MX
Li
Yu-fei
YF
Liu
Biao
B
Di
Xiao-ling
XL
Xiao
Xin-wu
XW
Mao
Ye-jian
YJ
Wu
Hua-ping
HP
Xie
Zhao-jun
ZJ
Xie
Hao
H
Zhang
Jian-ping
JP
Liu
Hai-lin
HL
Li
Ji-chuan
JC
Shen
Zhi-cong
ZC
Yang
Ming
M
Wang
D000293:Adolescent; D000328:Adult; D002681:China / Q000453:epidemiology; D017714:Community-Acquired Infections / Q000453:epidemiology; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D055815:Young Adult