EPIDEMIOLOGY OF INVASIVE HAEMOPHILUS-INFLUENZAE INFECTIONS IN ENGLANDAND WALES IN THE PRE-VACCINATION ERA (1990-2)

This survey defined the pattern of invasive Haemophilus influenzae inf ections during 1990-2 in six regions in England and Wales during the p re-vaccination era providing a baseline against which any changes in p atterns of disease due to the introduction of the Haemophilus influenz ae type b vaccination programme can be monitored. A total of 946 cases of invasive Haemophilus influenzae were recorded during the survey pe riod of which almost 90% were due to type b and most of the remainder were non-typeable. Type b infections occurred predominantly in childre n less than 5 years of age (88%) with the highest attack rate in male infants in the 6-11 month age group. Diagnostic category varied with b oth age and serotype; meningitis was the commonest presentation overal l but pneumonia and bacteraemia were more common in adults and non-typ eable isolates. Mortality was highest in neonates and the elderly (ove r 65 years of age) who were more likely to have an underlying predispo sing condition than older children and adults. Children under 5 years of age had a higher case fatality rate for non-typeable than for type b infections. Ampicillin resistance was 15% and there were no cefotaxi me resistant type b isolates.