Resurgence of measles in Serbia 2010-2011 highlights the need for supplementary immunization activities.

Between December 2010 and August 2011 an outbreak of measles occurred in Serbia with 363 reported cases. Sera and/or nose/throat swabs were collected from 193 patients and tested for measles-specific IgM antibodies by ELISA and viral RNA by RT-PCR, respectively. Epidemiological data were obtained from the surveillance database of the Institute of Public Health of Serbia. Of the 363 cases involved in the outbreak, 113 were laboratory confirmed. More than one third of the patients were hospitalized (n = 130, 35.8%) and for 15 (4.1% of the reported outbreak cases) the infection was complicated by pneumonia. Mostly pre-school children aged 4 years (37.8%) and adults aged 30 years (27.3%) were affected. The majority of patients belonged to the Roma population with a preponderance of female cases (57.0%). Nearly 94% of the patients were either unvaccinated or of unknown vaccination status. The main outbreak virus was the D4-Hamburg strain. The outbreak in Serbia occurred after several years of very low measles incidence despite a high routine immunization coverage in the general population, suggesting that special efforts to identify and vaccinate susceptible population groups are required even in countries with apparently good disease control.