Eurosurveillance - Volume 13, Issue 16, 17 April 2008

This week’s edition of Eurosurveillance is dedicated to European Immunization Week 2008, which will take place from 21 to 27 April. In 2005, the World Health Organization (WHO) organised the first European Immunization Week (http://www.euro.who.int/vaccine/eiw/20050608_1) to increase vaccination coverage by raising awareness about the importance of immunisation, with a special focus on reaching vulnerable and hard-to-reach population groups. During the week, each participating country implements activities to inform and engage key target groups using the slogan “prevent-protect-immunise” and focuses on critical challenges regarding immunisation in their country.

The World Health Organization (WHO) Regional Office for Europe established the European Immunization Week (EIW, http://www.euro.who.int/vaccine) in 2005 for three reasons: 1) to raise public awareness of the benefits of immunisation, 2) to support national immunisation systems, and 3) to provide a framework for mobilising public and political support for governmental efforts to protect the public through universal childhood immunisation.

Despite efforts to eliminate measles in Europe [1] outbreaks still continue unabated and even cause deaths. In 2006 and 2007 several countries have reported high numbers of cases and outbreaks. The larger outbreaks such as those described in Switzerland [2], Germany [3,4] and Spain [5] mostly involved the general population. Other outbreaks were described primarily affecting particular groups such as the travellers' communities in the United Kingdom [6,7] and Norway [8], Roma and Sinti populations in Italy [9], Roma and immigrant families in Greece [10] and orthodox Jewish communities in Belgium [11] and the UK [7,12]. The groups in the UK are known to historically have low vaccine uptake [13]. .

From the second week of March 2008, public health authorities in the province of Salzburg observed an increased number of measles cases compared to previous years. Twenty cases of measles had been were notified Austria-wide in 2007, 24 in 2006, 10 in 2005, and 14 in 2004. The current outbreak has affected, as of 14 April, 202 people in Austria, 53 in Germany, and four in Norway, bringing the total number of cases related to this outbreak to 259. The initial case series investigation revealed that the common link was attendance of an anthroposophic school and day care centre in Salzburg city. The majority of the pupils were not vaccinated against measles.

Between 7 January and 16 March 2008, 16 cases of measles were reported in the region of Apulia in south-eastern Italy (about four millions inhabitants). This outbreak is currently ongoing: we present here a preliminary report.

A cluster of rubella has been identified by the Infectious Disease Prevention and Control Unit (IDCU) of Malta in the beginning of January 2008. Two men and a woman aged between 23 and 28 years were affected. The index case had onset of illness on 23 December 2007. The second case had onset of rash on 3 January and the third case displayed symptoms on 6 January 2008. Two of the three cases were laboratory-confirmed (IgM positive), the third displayed typical symptoms and was a close contact of a laboratory-confirmed case but was IgM and IgG negative. None of the affected patients had received vaccination against rubella and there was no history of recent travel abroad. All three cases were linked through a work place. Blood samples were submitted to the World Health Organization (WHO) Regional Reference Laboratory for Measles and Rubella, Luxembourg, for further investigations. None of the cases had any complications. To date no further cases have been identified.

A cross-sectional study was conducted in order to determine the prevalence of mumps and measles antibodies in a representative sample of the general population in Northern Greece between January 2004 and May 2007. Overall, 900 healthy individuals participated in the study. The great majority were found to be protected against measles. The total protection rate against mumps was significantly less (87% versus 72%, respectively; p<0.01). Compared to all other age groups, statistically significantly lower protection rates were found in children younger than 1.5 years (p<0.01). The lowest rates of all adult groups were found in the age group of 21 to 30 years (86% and 68% for measles and mumps, accordingly). In conclusion, protection rates against both measles and mumps seem to be lower than expected in certain age groups, such as infants and young adults.

The Czech Republic has had a two-dose measles, mumps and rubella (MMR) vaccination programme since 1987. The last outbreak of mumps was reported in 2002, but an increase in the number of mumps cases was observed in 2005, starting in October that year. We analysed routinely collected surveillance data from 1 January 2005 to 30 June 2006 to show the magnitude of the increase and describe the most affected groups in order to better target prevention and control strategies. In the 18-month period examined, 5,998 cases of mumps were notified, with a peak incidence in May 2006. No deaths were recorded, but 21% of cases were hospitalised. Incidence was lowest in the Plzeň region (1.9/100,000) and highest in Zlín (118.6/100,000). There were more male (61.8%) than female cases. The age of the cases ranged from 0 to 80 years. The highest incidence rate was observed in the age group of 15 to 19 years, in which 87% of cases had received two doses of mumps vaccine. The average age of unvaccinated cases was 22.9 years, while for cases vaccinated with two doses it was 14.5 years. Although vaccine effectiveness could not be calculated from the data available, possible reasons for highly-vaccinated cases occurring are discussed.

We report on three cases of symptomatic transmission of the L-Zagreb mumps vaccine virus from three vaccinated children to five adult contacts. The five contact cases were parents of the vaccinated children and presented with parotitis and in one case also with aseptic meningitis. The etiology of the contacts' illness was determined by viral culture, genomic sequencing, serology and epidemiological linking. Two of the vaccinated children developed vaccine associated parotitis as an adverse event three weeks following immunization. Symptoms in contact cases developed five to seven weeks after the vaccination of the children. The five contact cases, as well as the three children with adverse events recovered completely. The children had been vaccinated with MMR vaccine produced by the Institute of Immunology Zagreb, each of them with a different lot. One of the possible explanations for these adverse events is that the very low levels of wild mumps virus circulation in the last decade, combined with waning immunity in those who received one dose of vaccine or suffered from mumps in childhood, resulted in susceptible young adults and that this unique epidemiological situation allows us to detect horizontal transmission of mumps vaccine virus.