Epidemiology and Infection

Carriage of a new epidemic strain of Neisseria meningitidis and its relationship with the incidence of meningococcal disease in Galicia, Spain

a1 Dirección Xeral de Saúde Pública, Xunta de Galicia, Santiago de Compostela
a2 Laboratorio de Neisserias, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid


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.

(Accepted July 16 1999)

c1 Author for correspondence: Servicio de Información sobre Saúde Pública, Dirección Xeral de Saúde Pública, Xunta de Galicia, Camiño Francés, 10, 15771 Santiago de Compostela, España.