A REVIEW OF THE MEASLES OUTBREAK IN GREECE FOR THE YEARS 2010-2011

Background

Measles is a highly contagious disease that can cause serious complications and lead even to death. In the period 2007–2011, outbreaks were reported in many countries in the western part of Europe, due to the accumulation of susceptible people over the previous few years, which allows sustained transmission. Measles viruses continue to spread across the European Region, leading to thousands of cases in people who are not immunized or not immunized on time. Outbreaks can be expected where coverage is below 95% for two doses of measles‐containing vaccine (MCV2) [Figure1].

Methods & Materials

Measles is a notifiable disease in Greece. The case definition currently in use is that of the European Union published in 2008. Measles cases were notified through the mandatory notification system; data were collected and analyzed in the Hellenic Centre of Diseases Control and Prevention (HCDCP). Genotyping was performed by the Hellenic Pasteur Institute.

Results

In total, 189 measles cases were notified to HCDCP of which 149 in 2010 and 40 in 2011 corresponding to an annual incidence of 1.32/100,000 population and 0.35/100,000 for 2010 and 2011 respectively. The first case was notified on 29 January 2010 and the last on 23 August 2011.

 Case classification

One hundred twenty six cases out of the total 189 (67%) were laboratory confirmed by either PCR and/or PCR while 24 (13%) fulfilled the criteria to be classified as probable (meeting clinical criteria with an epidemiological link) and 39 (20%) as possible (meeting only the clinical criteria). [Figure 2].

 Genotyping

Measles virus genotyping performed in 28 pharyngeal swab and urine samples by the National Measles Reference Laboratory in the Hellenic Pasteur Institute revealed 27 cases of genotype D4 and 1 of D6. The samples came from 18 cases of Greek nationality, 9 Bulgarians and 1  Albanian.

 Population and Geographical distribution

During the 2 years of the outbreak, the majority (74.1%) of cases were individuals of Greek nationality of which 55% (77%) didn’t belong to a specific high risk group, 39.3% (55) belonged to the Greek Roma community and 8 (5.7%) were health-care workers. The rest of the notified cases belonged to Roma communities of Bulgarian nationality (20.6%, 55 cases) mainly living under poor conditions and working as seasonal workers  while 5.3 % (10) were other foreign nationals. The first measles’ clusters were reported from the district of Ilia in the Peloponnese and followed by others in the two districts in the island of Crete (Chania and Heraklion) without any apparent connection between them. As the outbreak progressed  cases/clusters  were reported from various districts around Greece , the distribution of which are presented in Figure 3.

 Outbreak progress

The outbreak onset occurred in individuals of Bulgarian nationality who represented the majority of cases in the first 7 weeks. During the outbreak evolution, cases in Greek population were reported; mainly children <14 years old of Greek Roma communities after the 21st week) and to a less extent Greek non-minority population. In 2011, after a 5 week’s interval, the outbreak continued principally in Greek nationals who didn’t belong to a specific subpopulation group (80%). [Figure 4]

Age distribution

More than half (50.8%) of the cases were children 0-14 years old while 58/189 reported cases (30.7%) belonged to the 0-4 years age group. The majority of measles cases (24/39, 61.5%) in Bulgarian nationals were children 0-14 years of which 38.5% ( 15/39) 0-4 years. Nearly all (96.4%) cases in Greek Roma were children 0-14 years, with 58.2 % of the cases in children 0-4 years. Reported cases in Greek non-minority population represented mainly (74.1%) young adults over the age of 20 years.

 Vaccination Coverage

Vaccination status was known in 84.7% (150/189) of reported cases; of which 85.3 % were reported as unvaccinated and 14.7% have had ≥1 dose of MCV. Vaccination coverage by age group and population group is presented in Figure 5.

Control Measures

In response to the outbreak the following public health measures were implemented:

•Information for the ongoing outbreak in Greece and the one in the neighboring Bulgaria as well as  for the appropriate investigation and the management of the disease (case isolation, contact tracing and vaccination of susceptible contacts) were provided to the local and regional public health authorities and to healthcare professionals from the public and private sector. • Guidelines for measles control were distributed to healthcare staff and are available on the website of the HCDCP (www.keelpno.gr). • Physicians were alerted for the identification of further measles cases and advised to complete routine vaccination of children, adolescents and young adults according to the National Immunization Programme. • Prioritized vaccination campaigns of population groups with low vaccine coverage (mainly the Roma community) were organized in affected areas.   Conclusions

Despite the existence of effective vaccines, measles outbreaks continue to occur throughout Europe. The development of this outbreak underlines the need to ensure high vaccination coverage with 2 doses of a measles containing vaccine in children, adolescents and young adults taking special care in reducing pockets of undervaccinated populations as the Roma minority or immigrants, which undermine achieving  the goal of eradicating measles from Europe by 2015.

Part of Session

Epidemiology