Melbourne School of Population and Global Health - Theses

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End date: 2009 × Start date: 2000 × Subject: Victoria × Subject: cohort analysis ×

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    The epidemiology and impact of viral respiratory infections in pre-school aged children
    Lambert, Stephen Bernard ( 2009)
    BACKGROUND: There are significant gaps in our knowledge of the epidemiology of globally endemic respiratory viruses. Current community research methods are expensive, requiring invasive specimen collection at a home visit by health‐care workers. METHODS: Two cohort studies were conducted to collect better information about the epidemiology and impact of community‐managed respiratory illnesses in pre‐school aged children. The pilot study recruited 121 Melbourne children aged one to four years over winter/spring of 2001. Parents collected daily respiratory symptoms and completed an impact diary, including time seeking health‐care and caring for an ill child, when a pre‐defined acute respiratory illness (ARI) occurred. The Respiratory Virus Study (ReVS) followed 234 Melbourne children less than five years of age for approximately one year from January 2003. A combined nose‐throat swab (NTS), collected by parents when an ARI occurred, was added to pilot study methods. NTS specimens were transported to the Victorian Infectious Diseases Reference Laboratory (VIDRL) for polymerase chain reaction (PCR) to test for influenza A, influenza B, respiratory syncytial virus (RSV), parainfluenza viruses I, II, and III, adenoviruses, and picornaviruses (rhinoviruses, enteroviruses). At the end of the study, available specimens and nucleic acid extracts were shipped on dry ice to the Queensland Paediatric Infectious Diseases (Qpid) Laboratory and tested for human metapneumovirus and human coronavirus NL63. RESULTS: The incidence rate for community‐managed ARI in the pilot study was 0.44 episodes per childmonth (95% CI 0.38 to 0.51) with an average cost per illness of $241 (95% CI $191 to $291). The key cost driver was carer time away from usual activities caring for the ill child, making up 70% of costs. There were 730 ARIs identified in ReVS children for a rate of 0.48 ARIs per child‐month (95% CI 0.45 to 0.52). At least one virus was identified in 401 of 543 ARIs (74%) with a specimen returned, and picornaviruses were identified in 269 ARIs (50%). The total cost of all illnesses with a burden diary returned was $161,454, with over one‐third, $52,597, from illnesses where a picornavirus was identified in isolation. The mean cost of all ARIs was $309 (95% CI $263 to $354), and time spent caring for an ill child was again the key cost driver, responsible for 82% of all costs. The point estimate for the mean cost of influenza A illnesses ($904; 95% CI $89 to $1,719) was three times higher than RSV ($304; 95% CI $194 to $415), the next most expensive illness. Collection by a health‐care worker parent, collector‐reported quality, or presence of a throat swab made no difference to the proportion of specimens positive for any virus. DISCUSSION: Acute respiratory illnesses in community dwelling pre‐school aged children are common and a virus can be detected in 74% of parent‐collected specimens. Use of daily symptom diaries and parent‐collected specimens were effective and efficient study methods, and provide a new model for the future conduct of community‐based epidemiological studies for respiratory pathogens, including efficacy studies for new preventative vaccines and treatments.