Morbidity profiles of patients consulting during influenza and respiratory syncytial virus active periods

Abstract

We compared the burden of illness due to a spectrum of respiratory diagnostic categories among persons presenting in a sentinel general practice network in England and Wales during periods of influenza and of respiratory syncytial virus (RSV) activity. During all periods of viral activity, incidence rates of influenza-like illness, bronchitis and common cold were elevated compared to those in baseline periods. Excess rates per 100,000 of acute bronchitis were greater in children aged <1 year (median difference 2702, 95% CI 929-4867) and in children aged 1-4 years (994, 95% CI 338-1747) during RSV active periods rather than influenza; estimates for the two viruses were similar in other age groups. Excess rates of influenza-like illness in all age groups were clearly associated with influenza virus activity. For common cold the estimates of median excess rates were significantly higher in RSV active periods for the age groups <1 year (3728, 95% CI 632-5867) and 5-14 years (339, 95% CI 59-768); estimates were similar in other age groups for the two viruses. The clinical burden of disease associated with RSV is as great if not greater than influenza in patients of all ages presenting to general practitioners.

Fig. 1

The incidence rate of lower respiratory tract infections in the 45–64 years (–––) and 65–74 years (·······) age groups contrasted with laboratory reports of RSV () and influenza () over 10 years 1994/1995 to 2003/2004 (starting 1994 week 40 ending 2004 week 20).

Fig. 2

Cumulative excess incidence of upper respiratory tract infection (URTI) and lower respiratory tract infection (LRTI) in influenza (■) and RSV (□) active periods for persons aged (a) 1–4 years, (b) 25–44 years and (c) 65–74 years.

Fig. 3

Cumulative excess incidence of influenza-like illness (ILI) and acute bronchitis (AB) in influenza (■) and RSV (□) active periods for persons aged (a) 1–4 years, (b) 25–44 years and (c) 65–74 years.

Fig. 4

Median winter cumulative excess incidence (1994/1995 to 2003/2004) of acute bronchitis (AB), influenza-like illness (ILI), otitis media (OM) and common cold (CC) during influenza (■) and RSV (□) active periods, in (a) children aged <1, 1–4 and 5–14 years and (b) adults aged 15–24, 25–44, 45–64, 65–74 and ⩾75 years.