Description of two measles outbreaks in the Lazio Region, Italy (2006-2007). Importance of pockets of low vaccine coverage in sustaining the infection
1 Unit of Infecious Diseases and Vaccination, Department of Health Prevention and Promotion, Laziosanita' Agenzia di Sanita' Pubblica (ASP), Via Santa Costanza 53, 00198 Roma, Italy
2 Unit of Epidemiology and Bio-Statistics, Healthcare Department, The Bambino Gesù Children's Hospital, Piazza S Onofrio 4, 00165 Rome, Italy
3 National Centre for Epidemiology, Surveillance and Health Promotion (CNESPS), Istituto Superiore di Sanità (ISS), Via Giano della Bella 34 - 00162 Rome, Italy
4 Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy
5 Scientific Directorate, Laziosanita' Agenzia di Sanita' Pubblica, Via Santa Costanza 53, 00198 Rome, Italy
6 Department of Health Prevention and Promotion, Laziosanita' Agenzia di Sanita' Pubblica, Via Santa Costanza 53, 00198 Rome, Italy
BMC Infectious Diseases 2010, 10:62 doi:10.1186/1471-2334-10-62Published: 11 March 2010
Despite the launch of the national plan for measles elimination, in Italy, immunization coverage remains suboptimal and outbreaks continue to occur. Two measles outbreaks, occurred in Lazio region during 2006-2007, were investigated to identify sources of infection, transmission routes, and assess operational implications for elimination of the disease.
Data were obtained from several sources, the routine infectious diseases surveillance system, field epidemiological investigations, and molecular genotyping of virus by the national reference laboratory.
Overall 449 cases were reported, sustained by two different stereotypes overlapping for few months. Serotype D4 was likely imported from Romania by a Roma/Sinti family and subsequently spread to the rest of the population. Serotype B3 was responsible for the second outbreak which started in a secondary school. Pockets of low vaccine coverage individuals (Roma/Sinti communities, high school students) facilitated the reintroduction of serotypes not endemic in Italy and facilitated the measles infection to spread.
Communities with low vaccine coverage represent a more serious public health threat than do sporadic susceptible individuals. The successful elimination of measles will require additional efforts to immunize low vaccine coverage population groups, including hard-to-reach individuals, adolescents, and young adults. An enhanced surveillance systems, which includes viral genotyping to document chains of transmission, is an essential tool for evaluating strategy to control and eliminate measles