[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.
Yuan
Jun
J
Guangzhou Center for Disease Control and Prevention, China.
Li
Mei-xia
MX
Liu
Yu-fei
YF
Di
Biao
B
Xiao
Xiao-ling
XL
Mao
Xin-wu
XW
Wu
Ye-jian
YJ
Xie
Hua-ping
HP
Xie
Zhao-jun
ZJ
Zhang
Hao
H
Liu
Jian-ping
JP
Li
Hai-lin
HL
Shen
Ji-chuan
JC
Yang
Zhi-cong
ZC
Wang
Ming
M
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