Epidemiology of Haemophylus influenzae and meningococcal invasive diseases in a Spanish hospital (1987–2006)

Abstract number: 1733_1372

Blanco R., Unzaga M., Ezpeleta C., Alava J., Guerediaga I., Amezua B., Cabezas V., Cisterna R.

Objective: To describe the epidemiology of serogroup C meningococcal and Haemophilusinfluenzae invasive diseases and evaluate the efficacy of vaccination against them in Basurto Hospital.

Material and Methods: In the Basque Country scheduled vaccination with meningococcal conjugate vaccine (MCV4) began in 2000, previous sporadic campaigns of vaccination were performed since 1997. In 1996 the vaccine against Haemophilusinfluenzae was implemented too.

We evaluated the number of cases of CSF and bloodstream infections in the pre-vaccination period compared with those in post-vaccination period.

Results: The number of cases of serogroup B meningococcal invasive disease was 62 and 77 in the prevaccination period and post-vaccination period, respectively. The number of cases of serogroup C meningococcal invasive disease (SCMID) in the pre-vaccination period were 59 and 29 in the post-vaccination period; only 5 of them were detected in CSF. Among persons of 18 years and younger, the number of cases of SCMID reduced from 49 cases in the pre-vaccination period to 9 cases during the post-vaccination period. Three patients out of them were vaccinated, one of them was not and in the remaining 5 patients no data were available. The number of SCMID cases among persons older than 18 years increased from 3 to 16 cases in the post-vaccination period.

The number of cases of Haemophilus Influenzae invasive infections (HIID) in the prevaccination period was 65 and 35 in post-vaccination period, only 2 of them were detected in CSF. Among persons of 18 years and younger the number of HIID cases reduced from 25 cases in the pre-vaccination period to 6 cases during the post-vaccination period. One patient out of them was previously vaccinated, no data of vaccination were available in the others. The number of HIID among persons older than 18 years was reduced from 39 to 24 cases in the post-vaccination period.

Conclusion: Since the introduction of vaccination, the incidence of meningitis and bloodstream infections by Haemophilus Influenzae and serogroup C meningococci in the Basque Country is declining, which is partly caused by the natural fluctuation in the incidence of serogroup B meningococci. Nevertheless, the vaccination against serogroup C meningococcal disease as well as Haemophilus were very effectives and contributed significantly to the decline in the incidence of meningitis.