Human-to-human transmission of avian influenza A/H7N7, The Netherlands, 2003.
An outbreak of highly pathogenic avian influenza A virus subtype H7N7 began in poultry farms in the Netherlands in 2003. Virus infection was detected by RT-PCR in 86 poultry workers and three household contacts of PCR-positive poultry workers, mainly associated with conjunctivitis. To determine the magnitude of and risk factors for human-to-human transmission of influenza A/H7N7 in the Netherlands, a retrospective cohort study among household members of infected poultry workers was undertaken. In total, 33 (58.9%) of 56 (among 62) participants who provided blood samples had positive H7 serology, using single convalescent serum samples obtained at least 3 weeks after onset of symptoms of the index case. Eight household members (12.9%) reported symptoms (conjunctivitis and/or ILI), of which four of five (80.0%) tested seropositive. On univariate analysis, significant risk factors for seropositivity included having at least two toilets, a pet bird, and using cloth handkerchiefs. It was not possible to obtain a stable model for binomial regression for the outcome of A/H7N7 infection. Further seroprevalence studies among contacts of asymptomatic H7 cases should be conducted.
Du Ry van Beest Holle
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European Programme for Intervention Epidemiology Training, Centre for Infectious Diseases Epidemiology, National Institute for Public Health and the Environment, Bilthoven, the Netherlands.
Meijer
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Koopmans
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de Jager
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D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003231:Conjunctivitis / Q000821:virology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D053126:Influenza A Virus, H7N7 Subtype / Q000276:immunology; D007251:Influenza, Human / Q000150:complications / Q000635:transmission*; D008875:Middle Aged; D009426:Netherlands; D012189:Retrospective Studies; D012307:Risk Factors; D016036:Seroepidemiologic Studies
D000914:Antibodies, Viral