In Galicia, Spain, a dramatic increase in the incidence of meningococcal disease was seen in
the 1995–6. The annual incidence rose to 11 per 105 inhabitants, and 80% of identified strains
were C[ratio ]2b[ratio ]P1.2,5. This led to the implementation of an intensive A+C vaccination campaign
for the population aged 18 months to 19 years. During this campaign the prevalence of
carriage in areas with high and low incidence was studied. Nasopharyngeal swabs were taken
from 9796 subjects immediately before the administration of meningococcal vaccine, plated
onto Thayer–Martin plates, incubated and sent for analysis to the Reference Laboratory for
Neisseria in Spain. The prevalence of the C[ratio ]2b[ratio ]P1.2,5 strains was 0·6% (95% CI 0·29–0·88) in
the high incidence area, and 0·41% (95% CI 0·00–1·04) in the low incidence area, and that of
serogroup C (all strains) 1·36% (95% CI 0·80–1·80) and 0·89% (95% CI 0·09–1·69)
respectively. The prevalence of N. meningitidis (all strains) was almost the same in both areas
(8%). Carriers of the epidemic strain were not found in the 2–4 year age group, that most
affected by the disease.
Our data showed a wide distribution but a low carriage rate of the epidemic strain
C[ratio ]2b[ratio ]P1.2,5 in the high and low disease incidence areas studied; the difference in the carriage
rates between the two areas was not statistically significant.