title: A field study of household attack rates and the effectiveness of macrolide antibiotics in reducing household transmission of pertussis.
abstract: Bordetella pertussis (whooping cough) is an endemic, highly contagious bacterial respiratory infection, which is notifiable to Australian state and territory health departments. Between 2008 and 2011 there was a substantial outbreak in New South Wales with an initial increase in cases occurring in North Coast New South Wales from late 2007. During September and October 2011 the North Coast Public Health Unit conducted a household study of secondary attack rates to assess the effectiveness of pertussis vaccination as well as the timely use of antibiotics in preventing household transmission. At the time the study was commenced, notified cases included a large proportion of individuals with a documented history of vaccination against pertussis. We found lower attack rates amongst vaccinated compared with non-vaccinated subjects in all age groups, with the exception of the 5-11 years age group, who were also primarily responsible for the introduction of pertussis into the household. There was an increased risk of pertussis transmission from the household first primary case to contacts when antibiotic treatment was commenced later than 7 days after the onset of symptoms compared with within 7 days. This protective effect of timely antibiotic treatment in relation to transmission highlights the need to control for antibiotic treatment in field studies of pertussis. The benefits of timely diagnosis and use of antibiotics in preventing household transmission underscore the importance of early presentation and diagnosis of pertussis cases, particularly in households with susceptible occupants.
authors.affiliation: Public Health Preparedness Epidemiologist,North Coast Public Health Unit, Lismore, New South Wales.
authors.forename: Janet B
authors.initials: JB
authors.lastname: Terry
authors.affiliation: Epidemiologist contractor, North Coast Public Health Unit, Lismore, New South Wales.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Flatley
authors.affiliation: Communicable Disease Public Health Officer, North Coast Public Health Unit, Lismore, New South Wales.
authors.forename: Debra J
authors.initials: DJ
authors.lastname: van den Berg
authors.affiliation: Associate Professor, Environmental Health, University Centre for Rural Health, New South Wales, and North Coast Sydney Medical School, University of Sydney, New South Wales and Southern Cross University, New South Wales and University of Western Sydney, New South Wales and University of Wollongong, New South Wales.
authors.forename: Geoffrey G
authors.initials: GG
authors.lastname: Morgan
authors.affiliation: Public Health Nurse, Immunisation Co-ordinator, North Coast Public Health Unit, Lismore, New South Wales.
authors.forename: Marianne
authors.initials: M
authors.lastname: Trent
authors.affiliation: Communicable Disease Public Health Officer, Immunisation Co-ordinator, North Coast Public Health Unit, Lismore, New South Wales.
authors.forename: John A
authors.initials: JA
authors.lastname: Turahui
authors.affiliation: Communicable Diseases CNC, Refugee/Multicultural Health Nurse, North Coast Public Health Unit, Lismore, New South Wales.
authors.forename: Michelle C
authors.initials: MC
authors.lastname: Greenwood
authors.affiliation: Director Public Health, North Coast Public Health Unit, Lismore, New South Wales.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Corben
authors.affiliation: Deputy Director Public Health, North Coast Public Health Unit, Lismore, New South Wales.
authors.forename: Greg J
authors.initials: GJ
authors.lastname: Bell
mesh_terms: D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001315:Australia / Q000453:epidemiology; D001886:Bordetella pertussis / Q000276:immunology* / Q000472:pathogenicity; D002648:Child; D002675:Child, Preschool; D018563:Disease Notification / Q000706:statistics & numerical data; D004196:Disease Outbreaks / Q000517:prevention & control*; D062665:Epidemiological Monitoring; D005191:Family Characteristics; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007223:Infant; D018942:Macrolides / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D010567:Pertussis Vaccine / Q000008:administration & dosage*; D061665:Time-to-Treatment; D016896:Treatment Outcome; D014611:Vaccination; D014917:Whooping Cough / Q000188:drug therapy* / Q000453:epidemiology / Q000517:prevention & control* / Q000635:transmission
chemical_list: D000900:Anti-Bacterial Agents; D018942:Macrolides; D010567:Pertussis Vaccine