We would first like to congratulate Cécile Viboud et al1 on the successful completion of the study of risk factors of influenza transmission in households as reported in the BJGP. We are sure it will yield much valuable information on the burden of disease as well as on its transmission.
The authors discuss diagnostic criteria and point out, quite correctly, that many people with influenza infection do not necessarily have a fever exceeding 38°C. However, few would argue that the likelihood of high fever is greater in children, and particularly in young children, than in adults. Hence, in the sensitivity analysis using a stricter case definition, the risk of secondary infection was increased in young children.
The study is based on 395 subjects with confirmed influenza who completed the follow-up. They were distributed across France, with between two and 61 cases reported from each region. Their mean age was 38.4 years: 10 children were aged 0–5 years and 28 between 6 and 15 years, together accounting for 13.6% of indexed subjects. The authors conclude that children play a major role in the dissemination of influenza. Given the increased likelihood of a febrile response to respiratory illness in children, the relatively small proportions of children recruited to this study seriously challenges their own conclusions. If epidemics are spread more from children than adults, it would be logical to expect an increased proportion of children at recruitment over the final proportion among contact cases.
- © British Journal of General Practice, 2005.
