Abstract

Measles re-emerged in some counties in Germany in 2005, despite increasing vaccination coverage rates in children at school entry in recent years, which had led to decreasing incidence (with the lowest incidence ever recorded, 0.2 cases per 100 000 inhabitants in 2004). Regional outbreaks have been detected by the mandatory reporting system in the states of Hesse and Bavaria. Although both outbreaks led to similar incidences in the affected areas (14 and 12 cases respectively per 100 000 inhabitants) they differed in age distribution, transmission patterns and measles virus genotype. In Hesse, 223 cases were submitted, from which 160 belonged to 41 clusters mainly defined by family or household contacts. Attack rate was highest in children aged between 1-4 years (102 cases per 100 000). Results of measles virus diagnosis showed genotype D4 and identical nucleotide sequences for all analysed cases from Hesse. In Bavaria, 279 cases were submitted, most of which had occurred in schools and preschool facilities. Age-specific attack rate was highest in children aged between 5-9 years (129 per 100 000). Laboratory diagnosed viruses were identified as genotype D6 and were identical at the nucleotide level. In both outbreaks the vast majority of cases (95% in Hesse and 98% in Bavaria) were in unvaccinated children, but vaccination coverage differed in the affected areas and was slightly lower in Bavaria than in Hesse. Local accumulation of unvaccinated children and their concentration in schools and kindergarten preceded the outbreak in Bavaria. Despite high average vaccination coverage levels, local variations may lead to regionally limited outbreaks.