Epidemiology of invasiveHaemophilus influenzaeinfections in England and Wales in the pre-vaccination era (1990–2)

Abstract

SUMMARYThis survey defined the pattern of invasive Haemophilus influenzae infections during 1990-2 in six regions in England and Wales during the pre-vaccination era providing a baseline against which any changes in patterns of disease due to the introduction of the Haemophilus influenzae type b vaccination programme can be monitored. A total of 946 cases of invasive Haemophilus influenzae were recorded during the survey period of which almost 90 % were due to type b and most of the remainder were non-typeable. Type b infections occurred predominantly in children 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 both age and serotype; meningitis was the commonest presentation overall but pneumonia and bacteraemia were more common in adults and non-typeable isolates. Mortality was highest in neonates and the elderly (over 65 years of age) who were more likely to have an underlying predisposing 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 cefotaxime resistant type b isolates.

AreHaemophilus influenzaeInfections a Significant Problem in India? A Prospective Study and Review

“…In our study, 65% of all invasive H. influenzae infections in children aged !5 years occurred in infants !1 year of age, and the age distribution showed a peak for children aged 6-9 months. We found that 8.8% of the cases of invasive Hib disease were in hospitalized adults, a finding similar to the 12% [39] and 9% [40] reported in hospital studies from the United States and the United Kingdom. In contrast to data for blood cultures from a single hospital in Pakistan [18] but similar to data for CSF isolates from Bangladesh [21] and the United States [41], 97% of the H. influenzae isolates we recovered from CSF and blood specimens were Hib.…”

Characterization of Encapsulated and Noncapsulated Haemophilus influenzae and Determination of Phylogenetic Relationships by Multilocus Sequence Typing

“…Noncapsulated (nontypeable) H. influenzae is commonly carried in the pharynx, is one of the major causes of acute otitis media, and can cause diseases of the upper and lower respiratory tract, including sinusitis and pneumonia. These isolates may also cause invasive disease, and serious non-Hib disease in children is more commonly due to noncapsulated isolates than to encapsulated isolates of the non-Hib serotypes (1,2,10,17). In some countries where the Hib conjugate vaccines are used (e.g., the United Kingdom) there has been an increase in adult invasive disease due to non-Hib isolates, most of which is due to noncapsulated isolates (34).…”

Nontypeable Haemophilus influenzae strains with the capsule‐associated insertion element IS1016 may mimic encapsulated strains

“…The capsule is a major determinant of the pathogenicity of H. influenzae. In the pre‐vaccination era, approximately 90% of the invasive cases were caused by type b strains (8, 9). Apart from the type b capsule, encapsulated strains can express five other structurally and antigenically distinct capsular polysaccharides (10).…”