Probable person to person transmission of novel avian influenza A (H7N9) virus in Eastern China, 2013: epidemiological investigation.
OBJECTIVE
To determine whether the novel avian influenza H7N9 virus can transmit from person to person and its efficiency.


METHODS
Epidemiological investigations conducted after a family cluster of two patients with avian H7N9 in March 2013.


METHODS
Wuxi, Eastern China.


METHODS
Two patients, their close contacts, and relevant environments. Samples from the patients and environments were collected and tested by real time reverse transcriptase-polymerase chain reaction (rRT-PCR), viral culture, and haemagglutination inhibition assay. Any contacts who became ill had samples tested for avian H7N9 by rRT-PCR. Paired serum samples were obtained from contacts for serological testing by haemagglutination inhibition assays.


METHODS
Clinical data, history of exposure before the onset of illnesses, and results of laboratory testing of pathogens and further analysis of sequences and phylogenetic tree to isolated strains.


RESULTS
The index patient became ill five to six days after his last exposure to poultry. The second patient, his daughter aged 32, who provided unprotected bedside care in the hospital, had no known exposure to poultry. She developed symptoms six days after her last contact with her father. Two strains were isolated successfully from the two patients. Genome sequence and analyses of phylogenetic trees showed that both viruses were almost genetically identical. Forty three close contacts of both patients were identified. One had mild illness but had negative results for avian H7N9 by rRT-PCR. All 43 close contacts tested negative for haemagglutination inhibition antibodies specific for avian H7N9.


CONCLUSIONS
The infection of the daughter probably resulted from contact with her father (the index patient) during unprotected exposure, suggesting that in this cluster the virus was able to transmit from person to person. The transmissibility was limited and non-sustainable.
Department of Acute Infectious Disease Control and Prevention, Jiangsu Province Center for Disease Control and Prevention, Nanjing, Jiangsu 210009, China.
Xian
X
Qi
Yan-Hua
YH
Qian
Chang-Jun
CJ
Bao
Xi-Ling
XL
Guo
Lun-Biao
LB
Cui
Fen-Yang
FY
Tang
Hong
H
Ji
Yong
Y
Huang
Pei-Quan
PQ
Cai
Bing
B
Lu
Ke
K
Xu
Chao
C
Shi
Feng-Cai
FC
Zhu
Ming-Hao
MH
Zhou
Hua
H
Wang
D000328:Adult; D000818:Animals; D001717:Birds; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D009980:Influenza A virus / Q000145:classification / Q000302:isolation & purification; D005585:Influenza in Birds / Q000453:epidemiology / Q000635:transmission* / Q000821:virology; D007251:Influenza, Human / Q000453:epidemiology / Q000635:transmission* / Q000821:virology; D008297:Male; D008875:Middle Aged; D020133:Reverse Transcriptase Polymerase Chain Reaction