Risk of influenza A (H5N1) infection among health care workers exposed to patients with influenza A (H5N1), Hong Kong.
The first outbreak of avian influenza A (H5N1) occurred among humans in Hong Kong in 1997. To estimate the risk of person-to-person transmission, a retrospective cohort study was conducted to compare the prevalence of H5N1 antibody among health care workers (HCWs) exposed to H5N1 case-patients with the prevalence among nonexposed HCWs. Information on H5N1 case-patient and poultry exposures and blood samples for H5N1-specific antibody testing were collected. Eight (3.7%) of 217 exposed and 2 (0.7%) of 309 nonexposed HCWs were H5N1 seropositive (P=.01). The difference remained significant after controlling for poultry exposure (P=.01). This study presents the first epidemiologic evidence that H5N1 viruses were transmitted from patients to HCWs. Human-to-human transmission of avian influenza may increase the chances for the emergence of a novel influenza virus with pandemic potential.
Buxton Bridges
C
C
Centers for Disease Control and Prevention, Influenza Branch, MS A-32, 1600 Clifton Rd., Atlanta, GA 30333, USA. ctb1@cdc.gov
Katz
J M
JM
Seto
W H
WH
Chan
P K
PK
Tsang
D
D
Ho
W
W
Mak
K H
KH
Lim
W
W
Tam
J S
JS
Clarke
M
M
Williams
S G
SG
Mounts
A W
AW
Bresee
J S
JS
Conn
L A
LA
Rowe
T
T
Hu-Primmer
J
J
Abernathy
R A
RA
Lu
X
X
Cox
N J
NJ
Fukuda
K
K
D000328:Adult; D000914:Antibodies, Viral / Q000097:blood*; D002353:Carrier State; D015331:Cohort Studies; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D017758:Infectious Disease Transmission, Patient-to-Professional; D053124:Influenza A Virus, H5N1 Subtype; D009980:Influenza A virus / Q000145:classification / Q000276:immunology*; D007251:Influenza, Human / Q000635:transmission*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016036:Seroepidemiologic Studies
D000914:Antibodies, Viral