MEASLES VIRUS SPREAD INITIATED AT INTERNATIONAL MASS GATHERINGS IN EUROPE, 2011

Monday, 13th of October 2014

[source]Euro Surveillance and Outbreaks Report[|source]

Infected but not yet symptomatic individuals can spread measles virus to others and may not be recognised as a source of infection. At mass gatherings (MGs), the high number of participants in a crowded setting can further increase the risk of MV transmission. Measles virus long-distance spread has repeatedly originated at international MGs by participants travelling back to their home country and, as reported in this study, has even been transmitted from one MG to the next. MGs therefore represent a test for countries approaching measles elimination.

In this study, the authors investigate measles virus transmission chains that were initiated at two coinciding international mass gatherings held in Rimini, Italy, in June 2011. The report documents that an adequate serological and molecular-epidemiological characterisation of cases linked to mass gatherings may be helpful in tracing international measles virus transmission pathways and identifying unprotected population groups. More details on the report are accessible at: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=20891

 ABSTRACT

Three parallel transmission chains of measles virus (MV) variant ‘D8-Villupuram’ (D8-V) originated from two coinciding international mass gathering (MG) events in Rimini, Italy, in June 2011. MV D8-V was independently introduced into Germany by two unvaccinated persons, and into Slovenia by one unvaccinated person who had attended these events. Secondary spread of D8-V was restricted to two generations of transmission in Slovenia as well as in Germany where the virus was further disseminated at another MG. Serological and epidemiological investigation of the D8-V-associated German and Slovenian cases revealed different antibody responses and age distributions. Primary infected young persons between 11 and 27 years-old were affected in Germany, whereas the group of Slovenian cases comprised adults aged from 28 to 47 years and a high proportion (9/14; 64%) of patients with secondary vaccine failure (SVF). Our study demonstrates that monitoring of MV transmission chains in an international context and adequate serological investigation of cases with remote vaccination can contribute to identify susceptibility gaps.