title: Determinants of acute respiratory infections in Soweto--a population-based birth cohort.
abstract: BACKGROUND
  Acute respiratory infections (ARIs) are an important cause of infant morbidity in both developing and developed countries, and they are the leading cause of death in poorer parts of the world. Respiratory viruses appear to be the most frequent microbiological pathogens, especially respiratory syncytial virus. It has been suggested that factors such as being male, overcrowding, poor access to medical care, low level of maternal education, and passive smoking are associated with contracting ARIs.
  
  
  METHODS
  A fixed birth cohort of 571 children was followed from birth to 1 year of age. The children were monitored for symptoms of ARIs during regular home visits.
  
  
  METHODS
  An urban low-income setting in Soweto, a township outside Johannesburg with an estimated 1.2 million inhabitants, including an estimated 45,000 children under 2 years of age.
  
  
  METHODS
  A total of 571 children were observed for 118,650 days.
  
  
  METHODS
  The incidence rate of ARIs. The determinants birth weight, breastfeeding, gender, crowding, passive smoking, indoor pollution, and sanitary facilities were analysed.
  
  
  RESULTS
  A total of 489 episodes of coughing or coughing and nasal discharge combined were recorded. Only the father's level of education and the number of people living in the household remained significant in the multivariate analyses. The incidence of severe ARIs was reduced among breastfed infants.
  
  
  CONCLUSIONS
  Our study supports previous observations suggesting that crowding and communal living conditions are important determinants of ARIs. Breastfeeding seemed protective against severe ARI. The lack of association with well-described risk factors such as low level of maternal education, gender and passive smoking could be due to lack of statistical power in this rather uniform population.
authors.affiliation: Skejby University Hospital/Viborg Hospital, Aarhus, Denmark. ines@dadlnet.dk
authors.forename: Ines A
authors.initials: IA
authors.lastname: Kristensen
authors.forename: Jørn
authors.initials: J
authors.lastname: Olsen
mesh_terms: D000208:Acute Disease; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D016012:Poisson Distribution; D011159:Population Surveillance / Q000379:methods; D011204:Poverty Areas; D012044:Regression Analysis; D012141:Respiratory Tract Infections / Q000453:epidemiology*; D012307:Risk Factors; D013019:South Africa / Q000453:epidemiology; D014505:Urban Population