Letter to the editor: The measles outbreak in Bulgaria, 2009-2011: an epidemiological assessment and lessons learnt--but not completely yet.

To the editor: The recent report by Muscat et al., on the 2009 to 2011 measles outbreak in Bulgaria, emphasised that this infectious disease still represents a health issue of concern that can re-emerge with a substantial magnitude in Europe [1]. Indeed, this epidemiological analysis recorded 24,364 cases in Bulgaria between April 2009 and December 2011 and, importantly, around 73% of those infected were children and adolescents < 15 years of age. According to a previous national survey, almost 30% of children aged 2 to 10 had not been immunised against measles [2]. Moreover, most cases occurred in the Roma ethnic group, where the immunisation rate was even lower than in the rest of the Bulgarian population [1].