Weekly incidence data for influenza-like illness, routinely collected in sentinel general practices in England and Wales and in the Netherlands over 10 winter periods (week 37 in one year to week 20 in the next, 1987/1988-1996/1997) were examined in conjunction with matching virus isolate data to define epidemic periods of influenza in the two countries.
We first defined the background rates of recording influenza-like illness which occurred at times when only sporadic or no isolations of virus were reported.
The background rates were similar in the two networks with mean weekly incidence in England and Wales of 28.1 per 100,000 (all ages) and in the Netherlands 29.8. Epidemic periods defined as lying above the upper 95% confidence level of the background rate lasted on an average of about 10 weeks.
Once epidemics were recognised, peak incidence was generally achieved within 4 weeks.
The excess population (all ages) consulting general practitioners during influenza epidemic periods was calculated from the difference between the observed and background incidence rates, and expressed as a percentage of the total population.
In the 10 periods surveyed, the percentage of the population consulting and diagnosed with influenza-like illness in England and Wales ranged from 0.4% in 1991/1992 to 1.7% in 1989/1990 and in the Netherlands from 0.5% in 1990/1991 to 2.1% in 1989/1990. (...)
Mots-clés Pascal : Grippe, Virose, Infection, Epidémie, Surveillance sanitaire, Epidémiologie, Incidence, Durée, Homme, Pays Bas, Europe
Mots-clés Pascal anglais : Influenza, Viral disease, Infection, Epidemic, Sanitary surveillance, Epidemiology, Incidence, Duration, Human, Netherlands, Europe
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 99-0414013
Code Inist : 002B05C02C. Création : 22/03/2000.