Molecular surveillance of measles and rubella in the WHO European Region: new challenges in the elimination phase.

BACKGROUND: The WHO European Region (EUR) has adopted the goal of eliminating measles and rubella but individual countries perform differently in achieving this goal. Measles virus spread across the EUR by mobile groups has recently led to large outbreaks in the insufficiently vaccinated resident population. As an instrument for monitoring the elimination process and verifying the interruption of endemic virus transmission, molecular surveillance has to provide valid and representative data. Irrespective of the country's specific situation, it is required to ensure the functionality of the laboratory surveillance that is supported by the WHO Global Measles and Rubella Laboratory Network. AIMS: To investigate whether the molecular surveillance in the EUR is adequate for the challenges in the elimination phase, we addressed the quality assurance of molecular data, the continuity and intensity of molecular monitoring, and the analysis of transmission chains. SOURCES: Published articles, the molecular External Quality Assessment Programme of the WHO, the Centralized Information System for Infectious Diseases of the WHO EUR and the WHO Measles and Rubella Nucleotide Surveillance databases served as information sources. CONTENT: Molecular proficiency testing conducted by the WHO in 2016 has shown that the expertise for measles and rubella virus genotyping exists in all parts of the EUR. The analysis of surveillance data reported nationally to the WHO in 2013-2016 has revealed some countries with outbreaks but not sufficiently representative molecular data. Long-lasting supranational MV transmission chains were identified. IMPLICATIONS: A more systematic molecular monitoring and recording of the transmission pattern for the whole EUR could help to create a meaningful picture of the elimination process.

Challenges of measles and rubella laboratory diagnostic in the era of elimination.

The Member States of the WHO European Region adopted the goal of measles and rubella elimination more than 10 years ago, but so far only 21 of 53 countries have reached this target. Laboratory investigation of suspected cases is essential to support disease elimination efforts. Therefore, WHO maintains a network of accredited laboratories providing high-quality testing. Laboratory investigation heavily relies on specific IgM serology and increasingly on virus detection by reverse transcription (RT)-PCR, but other methods such as IgG avidity testing and genetic characterization of virus strains have gained in importance. In elimination settings, often few samples from suspected cases are available for testing, but testing proficiency must be maintained. The predictive value of an IgM-positive result decreases and other rash-fever disease aetiologies become more important. In addition, cases with a rash after measles/rubella vaccination or with mild disease after waning of vaccine-induced antibodies are seen more often. Thus, it is necessary to perform comprehensive and potentially time-consuming and costly investigations of every suspected case using quality-controlled laboratory methods. At the same time rapid feedback to public health officers is required for timely interventions. The introduction of new laboratory methods for comprehensive case investigations requires training of staff under the supervision of WHO-accredited reference laboratories and the definition of appropriate test algorithms. Clinical, laboratory, and epidemiological data are essential for final case classification and investigation of chains of transmission in the endgame of measles and rubella elimination.

A sensitive one-step TaqMan amplification approach for detection of rubella virus clade I and II genotypes in clinical samples.

Although teratogenic rubella virus (RV) causes a vaccine-preventable disease, it is still endemic in several countries worldwide. Thus, there is a constant risk of RV importation into non-endemic areas. RV monitoring, especially during measles and Zika virus outbreaks, requires reliable diagnostic tools. For this study, a TaqMan-based one-step reverse transcription-quantitative PCR (RT-qPCR) assay, with the p90 gene as a novel and so far unexplored target for detection of clade I and II genotypes, was developed and evaluated. Automated nucleic acid extraction was carried out. Performance characteristics of the TaqMan RT-qPCR assay were determined for a RV plasmid standard and RNA extracted from virus-infected cell culture supernatants representing clade I and II genotypes. Diagnostic specificity and sensitivity were validated against other RNA and DNA viruses, relevant for RV diagnostic approaches and for RV-positive clinical samples, respectively. The assay is specific and highly sensitive with a limit of detection as low as five to one copies per reaction or 200 infectious virus particles per ml. The coefficients of variation (CV) were specified as intra- (within one run) and inter- (between different runs) assay variation, and calculated based on the standard deviations for the obtained Ct values of the respective samples. Intra- and inter-assay CV values were low, with a maximum of 3.4% and 2.4%, respectively. The assay was shown to be suitable and specific for the analysis of clinical samples. With p90 as a novel target, the highly sensitive and specific TaqMan assay outlined in this study is suitable for RV diagnosis worldwide.

Measles, mumps, rubella and VZV: importance of serological testing of vaccine-preventable diseases in young adults living with HIV in Germany.

Measles, mumps, rubella (MMR) and varicella zoster virus (VZV) infection can cause serious diseases and complications in the HIV-positive population. Due to successful vaccination programmes measles, mumps and congenital rubella syndrome has become neglected in Germany. However, recent outbreaks of measles have occurred from import-associated cases. In this cross-sectional study the serostatus for MMR and VZV in 2013 HIV-positive adults from three different university outpatient clinics in Bonn (n = 544), Cologne (n = 995) and Munich (n = 474) was analysed. Sera were tested for MMR- and VZV-specific immunglobulin G antibodies using commercial immunoassays. Seronegativity was found in 3% for measles, 26% for mumps, 11% for rubella and 2% for VZV. Regarding MMR, 35% of patients lacked seropositivity against at least one infectious agent. In multivariable analysis younger age was strongly associated with seronegativity against all four viruses, measles, mumps, rubella (P < 0·001, P < 0·001 and P = 0·001, respectively) and VZV (P = 0·001). In conclusion, there is high need for MMR and VZV vaccination in people living with HIV in Germany born in 1970 or later. Thus, systematic MMR and VZV antibody screening and vaccination should be implemented in the HIV-positive population to prevent serious disease and complications of vaccine-preventable diseases.

Long-term transmission of measles virus in Central and continental Western Europe.

The World Health Organization (WHO) has adopted an elimination goal for measles and rubella, which is supposed to be met in the WHO European Region (EUR) by 2015. For verification of elimination, it is required that the genotyping data of detected measles viruses provide evidence for the interruption of endemic transmission. In order to record and assess the extent of endemic measles virus (MV) circulation in a part of the EUR, we analyzed transmission chains of the epidemiologically most relevant MV variants identified in Central and continental Western Europe (CCWE) from 2006 to 2013. Based on MV sequence data deposited in the WHO global database for molecular surveillance of measles (MeaNS), the circulation period was calculated for each MV variant at the country-level and for the entire region of CCWE. The MV variants "D5-Okinawa," "D4-Hamburg," "D4-Manchester," and "D8-Frankfurt-Main" spread widely in CCWE; they caused large and long-lasting outbreaks with secondary spread that resulted in additional outbreaks. Nation-wide outbreaks (epidemics) with thousands of measles cases occurred in four countries (Switzerland, France, Bulgaria, and Romania) and were characterized by continuous detection of the same MV variant for more than 12 months suggesting endemic transmission. In the entire region of CCWE, the circulation period of the four predominant MV variants ranged from 18 to 44 months. The long-lasting MV transmission which affected predominantly unvaccinated individuals in different hard-to-reach groups and in the general population is not consistent with the measles elimination goal. Additional efforts are necessary to meet the elimination target in the EUR.

[Immunity against measles among healthcare personnel at the University Hospital Frankfurt, 2003-2013]. / Immunität gegen Masern beim medizinischen Personal des Universitätsklinikums Frankfurt, 2003-2013.

BACKGROUND: Despite aiming for the elimination of measles by 2015, the current epidemiological situation in Germany shows that there is still insufficient vaccination coverage among the population. During the present pre-elimination period, nosocomial measles are gaining in importance. AIM: The purpose of our study was to determine the immune status of measles among healthcare personnel and medical students at the University Hospital Frankfurt. Moreover, the knowledge of study participants regarding the WHO's goal of the elimination of measles and the general attitude towards vaccination recommendations were investigated. METHODS: A retrospective study of measles seroprevalence was conducted among healthcare personnel and students at the University Hospital Frankfurt with an observation period of 11 years. In spring 2014, medical students were asked to complete an anonymous questionnaire regarding vaccination status, knowledge of measles and acceptance of measles vaccination recommendations. RESULTS: In total, 9,933 serologies were evaluated and 85.7% of the participants had sufficient immunity against measles. Significant changes in immunity to measles over time were not observed. However, a significant difference in the immunity rate of participants born before 1970 and those born after1970 was found. Participants born before 1970 significantly more often showed sufficient immunity against measles compared to those born later (96.4 vs. 83.3 %, p < 0.0001). Almost 20 % of the medical students were not aware of their measles vaccination status and merely 70.7 % indicated that they had received two measles vaccinations. Furthermore, only 45.4 % of the medical students were familiar with the WHO's goal of eliminating measles by 2015; however 95 % could be classified as vaccination-supporters on the basis of the questionnaire. CONCLUSIONS: Overall, the immunity rate of measles determined by serology within the study population did not reach the WHO goal of ≥ 95 %, and this gap was even greater in group of medical students. Despite the medical students' positive attitude towards vaccination guidelines, the awareness in this field awaits improvement.

Measles virus spread initiated at international mass gatherings in Europe, 2011.

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.

Mumps virus infection in vaccinated patients can be detected by an increase in specific IgG antibodies to high titres: a retrospective study.

Mumps outbreaks in highly vaccinated populations with genotype G have been reported repeatedly. Detection of these outbreaks can be difficult in a setting with relatively high vaccination coverage when acute cases of mumps are routinely diagnosed by IgM serology since this marker is not reliable for diagnosis of mumps re-infection. To learn whether diagnostic tests performed in a large private laboratory may be useful to detect mumps outbreaks retrospectively, we reviewed the results of almost 7000 mumps tests. Two groups were compared: group 1 comprised of 3438 samples from patients submitted by physicians and clinicians (it was assumed that these patients visited their doctor due to acute disease). Group 2 comprised of 3398 samples submitted from company medical officers and occupational physicians. Since these patients usually attend for routine check-ups and certification of immunity to vaccine-preventable diseases, these samples comprised a control group. From July 2010 to May 2011, a mumps virus outbreak with more than 300 cases occurred in Bavaria, Southeast Germany. Our study includes samples received for serological mumps tests from January 2009 until December 2011 (36 months). The two groups were analysed with regard to the number of IgM-positive cases per month and the level of IgG titre. We found a marked increase for both parameters in group 1 during the time of the outbreak, while the samples submitted by the occupational medical physicians did not display significant alterations. These parameters reflect the outbreak with high accuracy, indicating that a retrospective analysis of IgG titres may be a useful tool for detection of mumps outbreaks when, as was the case in Germany, (i) a nationwide notification system has not been implemented and (ii) a highly vaccinated population is affected.

Measles outbreak spreading from the community to an anthroposophic school, Berlin, 2011.

Between April and July 2011 there was an outbreak of measles virus, genotype D4, in Berlin, Germany. We identified 73 case-patients from the community and among students of an anthroposophic school, who participated in a 4-day school trip, as well as their family and friends. Overall, 27% were aged ≥ 20 years, 57% were female and 15% were hospitalized. Of 39 community case-patients, 38% were aged ≥ 20 years, 67% were female and 63% required hospitalization. Unvaccinated students returning from the school trip were excluded from school, limiting transmission. Within the group of 55 school-trip participants, including 20 measles case-patients, a measles vaccine effectiveness of 97.1% (95% confidence interval 83.4-100) for two doses was estimated using exact Poisson regression. Our findings support school exclusions and the recommendation of one-dose catch-up vaccination for everyone born after 1970 with incomplete or unknown vaccination status, in addition to the two-dose routine childhood immunization recommendation.

Transmission and molecular characterisation of wild measles virus in Romania, 2008 to 2012.

Molecular characterisation of measles virus is a powerful tool for tracing transmission. Genotyping may prove the absence of endemic circulation of measles virus, i.e. transmission for more than 12 months, which is one of the criteria for verifying elimination of the disease. We have genetically characterised measles viruses detected in Romania from 2008 to 2012, focusing on the recent outbreaks from 2010 to 2012 that affected mainly groups with limited access to healthcare and schools. The findings emphasise the importance of genotyping during the different phases of an outbreak. A total of 8,170 cases were notified, and 5,093 (62%) of the 7,559 possible cases were serologically confirmed. RT-PCR was performed for 104 samples: from the 101 positive samples obtained from sporadic measles cases or clusters from different counties, 73 were genotyped. Sporadic measles cases associated with D4 and D5 viruses were observed from2008 to 2009. Genotype D4-Manchester was predominant in 2011 and 2012. In addition, the related variant D4-Maramures and MVs/Limoges.FRA/17.10[D4] and a few D4-Hamburg strains were detected. The detection of several distinct MV-D4 genotypes suggests multiple virus importations to Romania. The outbreak associated with D4 genotype is the second largest outbreak in Romania in less than 10 years.

[Molecular surveillance shows progress in measles elimination process]. / Molekulare Surveillance belegt Fortschritt im Eliminationsprozess der Masern.

Measles is a severe disease caused by infection with the measles virus. Complications after the onset of infection lead to 1-3 fatalities per 1,000 cases in industrialized countries. If more than 95 % of the global population were vaccinated twice with the measles, mumps, and rubella (MMR) vaccine, measles could be eliminated worldwide. The elimination of measles and rubella should be reached in the WHO Europe region in 2015. One important criterion for elimination of the measles virus consists in the analysis of the duration of transmission chains initiated by the import of measles virus. To assign measles viruses to outbreaks and transmission chains, genetic characterization is necessary. These investigations have been performed continually at the National Reference Center Measles, Mumps, Rubella since 1999, when the German Intervention Program was launched. This article summarizes our experiences with measles virus genotyping and new developments with respect to measles elimination in Germany.

[Vaccination coverage against measles and sero-epidemiology of measles-specific IgG antibodies in German children and adolescents]. / Durchimpfung und Prävalenz von IgG-Antikörpern gegen Masern bei Kindern und Jugendlichen in Deutschland.

BACKGROUND: Measles is a vaccine-preventable disease that could be eliminated by global vaccination strategies with two-dose measles vaccination. The World Health Organization (WHO) European Region aims at achieving measles elimination by 2015. Target control is mainly based on verification of 95 % vaccination coverage. In Germany, target verification cannot be based on data from centrally collected registers on vaccination and seroprevalence of measles-specific antibodies. OBJECTIVE: This paper provides an overview of measles vaccination coverage and the timeliness of measles vaccination in birth cohorts 1989-2008. In addition, factors associated with vaccination gaps are described. METHODS: Primary data on vaccination coverage (annual school entrance health examination) and on vaccination coverage and immune status (population-based German Health Interview and Examination Survey for Children and Adolescents - KiGGS) and secondary data (insurance refund claim data) are described and discussed. RESULTS AND CONCLUSION: The measles immunization coverage (two doses) obtained in the 2010 school entrance examinations was 91.5 %. The range was 87.6-95.3 % between Federal States. Regional differences were even more pronounced between districts. The timeliness of the two-dose measles immunization increased from 41 % (birth cohorts 2001/2002) to 66 % (birth cohorts 2006/2008). Despite progress in recent years, measles vaccination coverage is still inadequate in adolescents, young adults, and young children. The German Standing Committee on Vaccination (STIKO) recommends a combined MMR vaccination of adults who were born after 1970 and who were not fully vaccinated against measles during childhood. Successful implementation of this recommendation is crucial just as it is important to step up efforts to improve the timeliness of measles vaccination in young children. Regional vaccination gaps and susceptible clusters defined by age or sociodemographic parameters are of particular importance to the epidemiology of measles disease. Knowledge of the factors associated with nonimmunization should be used to tailor vaccination strategies.

[Measles surveillance in Germany. From sentinel to mandatory surveillance]. / Masern-Surveillance in Deutschland. Vom Sentinel zur Meldepflicht.

From September 1999 to March 2011, sentinel surveillance of measles was conducted by a self-selected sample of private physicians in Germany. From 2001, when mandatory surveillance for measles was established, two surveillance systems worked in parallel. The aim of this article is to summarize the strengths and limitations of sentinel versus mandatory surveillance. Active monthly reporting included case-based questionnaires on patients with (suspected) measles or zeroreporting. For confirmation of measles, the diagnostic patient specimens were sent to regional laboratories for serological tests or to the National Reference Laboratory (NRC). In the NRC in addition to serological tests measles-virus (MV) detection by PCR in urine, throat swabs, and oral fluid (since 2003) as well as MVgenotyping was offered. From January 2000 to December 2010, 934 out of 1,488 participating sentinel-practices did not see any measles case, while 554 reported 3,573 suspected cases. Measles was confirmed by laboratory testing in 801 cases, excluded in 473 cases, and the diagnosis remained uncertain in 215 cases. Of 3,100 analyzed cases, 2,712 (87 %) were unvaccinated, 217 (7 %) and 32 (1 %) were vaccinated with one or two doses, respectively, and for 139 (4 %) cases the vaccination status was unknown. The main reason for not being vaccinated against measles was refusal (n = 1,383). The confirmation rate was lower in the vaccinated than in the unvaccinated patients (19 % vs. 63 %). Since 2006, sentinel-cases have differed from notified cases by region and age. The proportion of sentinel cases from all NRC-investigated cases decreased from more than 50 % (2002) to less than 5 % (since 2007). Sentinel surveillance allowed for the detection of trends, delivered additional information for measles prevention, and played a major role in measles diagnostics. Since mandatory surveillance was established and sentinel surveillance no longer reflected the epidemiologic situation, the latter was abandoned in April 2011.

Description of measles D4-Hamburg outbreak in Hamburg, Germany, December 2008 to June 2009, which disproportionally affected a local Roma community.

From December 2008 to June 2009 a measles outbreak occurred in the Federal State of Hamburg, Germany. The outbreak affected 216 persons and was caused by a new measles strain termed D4-Hamburg which led to consecutive outbreaks between 2009 and 2011 in at least 12 European countries. Here, we describe epidemiological characteristics of the outbreak and evaluate the control measures taken in Hamburg. In one of the seven boroughs of Hamburg a local Roma community comprised more than 50% of the notified cases.We compared in a stratified analysis the age distribution of these cases with cases of fellow citizens who did not belong to the Roma community. The age group of infants (0-11 months) comprised 33% among the non-Roma measles cases, while in the Roma community only 4% belonged to this stratum. In the stratum of 5-17 year-olds only 8% were affected among the non-Roma cases, whereas in the Roma community 50% belonged to this age group. We discuss the influencing factors that might have led to this difference in age distribution between the two groups.

Spotlight on measles 2010: measles outbreak in a mainly unvaccinated community in Essen, Germany, March-June 2010.

On 15 March 2010, a case of measles was reported to the District Health Office in Essen. In total 71 cases occurred from 15 March to 19 May (four cases hospitalised), with the majority linked to a Waldorf school. Only one case had been vaccinated twice, two cases had been vaccinated once. Immediate and consequent exclusion of non-immune children from classes for two weeks as well as the adjacent spring break prevented the wider spread of the virus.

Spotlight on measles 2010: An epidemiological overview of measles outbreaks in Poland in relation to the measles elimination goal.

The objective of this study was to describe transmission chains of measles observed in Poland during 2008-2009. A decade ago, the incidence of measles in Poland declined and approached one case per million inhabitants one of the World Health Organization's criteria for measles elimination. Following a period of very few reported measles cases (2003 to 2005), an increase in incidence was observed in 2006. Since then, the incidence has constantly exceeded one case per million inhabitants. Of 214 measles cases reported in 2008 and 2009 in Poland, 164 (77%) were linked to 19 distinct outbreaks, with 79% of cases belonging to the Roma ethnic group. Outbreaks in the non-Roma Polish population had different dynamics compared to those in the Roma population. On average, measles outbreaks in Roma communities involved 10 individuals, seven of whom were unvaccinated, while outbreaks in the non-Roma Polish population involved five individuals, half of whom were incompletely vaccinated. The majority of outbreaks in Roma communities were related to importation of virus from the United Kingdom. In six outbreaks, the epidemiologic investigation was confirmed by identification of genotype D4 closely related to measles viruses detected in the United Kingdom and Germany. Our data indicate that Poland is approaching measles elimination, but measles virus circulation is still sustained in a vulnerable population. More efforts are needed to integrate the Roma ethnic group into the Polish healthcare system and innovative measures to reach vulnerable groups should be explored.

Spotlight on measles 2010: preliminary report of an ongoing measles outbreak in a subpopulation with low vaccination coverage in Berlin, Germany, January-March 2010.

Since early January 2010, Berlin has been experiencing a measles outbreak with 62 cases as of 31 March. The index case acquired the infection in India. In recent years, measles incidence in Berlin has been lower than the German average and vaccination coverage in school children has increased since 2001. However, this outbreak involves schools and kindergartens with low vaccination coverage and parents with critical attitudes towards vaccination, which makes the implementation of public health interventions challenging.

Measles outbreak linked to a minority group in Austria, 2008.

We report on a measles outbreak originating in an anthroposophic community in Austria, 2008. A total of 394 (94.9%) cases fulfilled the outbreak case definition including 168 cases affiliated to the anthroposophic community. The source case was a school pupil from Switzerland. The Austrian outbreak strain was genotype D5, indistinguishable from the Swiss outbreak strain. A school-based retrospective cohort study in the anthroposophic school demonstrated a vaccine effectiveness of 97.3% in pupils who had received a single dose of measles-containing vaccine and 100% in those who had received two doses. The vaccination coverage of the cases in the anthroposophic community was 0.6%. Of the 226 outbreak cases not belonging to the anthroposophic community, the 10-24 years age group was the most affected. Our findings underline the epidemiological significance of suboptimal vaccination coverage in anthroposophic communities and in older age groups of the general population in facilitating measles virus circulation. The findings of this outbreak investigation suggest that the WHO European Region is unlikely to achieve its 2010 target for measles and rubella elimination.