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Importation and transmission of measles via air travel is a public health concern to countries, which are close to or have achieved elimination, i.e., to the majority of countries in Europe. In 2018, two measles cases occurred in Berlin residents, who flew within Europe while being infectious. In addition to contact tracing through passenger manifests, we contacted national authorities in flight destination countries or embarking countries and inquired about epidemiologically linked measles cases to the two Berlin index cases. We identified eight epidemiologically linked cases (six males, median age: 32 years) from three countries associated with three air-travels. Consequently measles was imported to Germany (Bavaria), Denmark and possibly Sweden. Our investigations revealed impediments to an effective public health response indicating the need to revisit current guidelines and methods to better control transmission of measles related to air travel., Competing Interests: Declaration of competing interest None., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Measles is a highly transmissible viral infection that may lead to serious illness, lifelong complications, and death. As there is no animal reservoir for measles, measles resurgence is due to human movement of viremic persons. Therefore, some have blamed the enormous migration into Europe in the past 5 years for the measles resurgence in this region. We set out to determine the main driver for measles resurgence in Europe by assessing vaccine coverage rates and economic status in European countries, number of migrants, and travel volumes. Data on measles vaccine coverage rates with two vaccine doses of measles, mumps and rubella (MMR) [Measles Containing Vaccine (MCV)2] and total number of measles cases in 2017 for Europe, including Eastern European countries, were obtained, in addition to Gross Domestic Product (GDP), and number of migrants and tourist arrivals. The outcome measured, incidence of measles per 100,000, was log transformed and subsequently analyzed using multiple linear regression, along with predictor variables: number of international migrants, GDP per capita, tourist arrivals, and vaccine coverage. The final model was interpreted by exponentiating the regression coefficients. Incidence of measles was highest in Romania (46.1/100,000), followed by Ukraine (10.8/100,000) and Greece (8.7/100,000). MCV2 coverage in these countries is less than 84%, with lowest coverage rate (75%) reported in Romania. Only vaccine coverage appears to be the significant predictor in the model ( p < 0.001) for incidence of measles even after adjusting for international migrants, international tourist arrivals, and GDP per capita. With one unit increase in vaccination coverage, the incidence of measles decreased by 18% [95% confidence interval (CI): 10-25]. Our results showed that number of migrants and international tourist arrivals into any of the European countries were not the drivers for increased measles cases. Countries with high vaccine coverage rates regardless of economic status did not experience a resurgence of measles, even if the number of migrants or incoming travellers was high. The statistically significant sole driver was vaccine coverage rates. These analyses reemphasize the importance of strategies to improve national measles vaccination to achieve coverage greater than 95%., Competing Interests: The authors declare they have no conflicts of interest., (© 2019 Atlantis Press International B.V.)

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.

Our ability to respond appropriately to infectious diseases is enhanced by identifying differences in the potential for transmitting infection between individuals. Here, we identify epidemiological traits of self-limited infections (i.e. infections with an effective reproduction number satisfying [0 < R eff < 1) that correlate with transmissibility. Our analysis is based on a branching process model that permits statistical comparison of both the strength and heterogeneity of transmission for two distinct types of cases. Our approach provides insight into a variety of scenarios, including the transmission of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) in the Arabian peninsula, measles in North America, pre-eradication smallpox in Europe, and human monkeypox in the Democratic Republic of the Congo. When applied to chain size data for MERS-CoV transmission before 2014, our method indicates that despite an apparent trend towards improved control, there is not enough statistical evidence to indicate that R eff has declined with time. Meanwhile, chain size data for measles in the United States and Canada reveal statistically significant geographic variation in R eff, suggesting that the timing and coverage of national vaccination programs, as well as contact tracing procedures, may shape the size distribution of observed infection clusters. Infection source data for smallpox suggests that primary cases transmitted more than secondary cases, and provides a quantitative assessment of the effectiveness of control interventions. Human monkeypox, on the other hand, does not show evidence of differential transmission between animals in contact with humans, primary cases, or secondary cases, which assuages the concern that social mixing can amplify transmission by secondary cases. Lastly, we evaluate surveillance requirements for detecting a change in the human-to-human transmission of monkeypox since the cessation of cross-protective smallpox vaccination. Our studies lay the foundation for future investigations regarding how infection source, vaccination status or other putative transmissibility traits may affect self-limited transmission.

Background: Flight-related measles contact investigations in the United States are coordinated by the Centers for Disease Control and Prevention (CDC). To evaluate the efficiency of CDC's measles protocol, we analyzed data from contact investigations conducted December 2008-December 2011., Methods: Cases were defined as travelers diagnosed with measles that were infectious at the time of the flight. Passengers seated within 2 rows of the case-traveler and all babies-in-arms were defined as contacts. Contact information obtained from airlines was distributed to US health departments; reporting of outcomes was requested. We cross-referenced the National Notifiable Diseases Surveillance System and CDC's National Center for Immunization and Respiratory Diseases to identify unreported cases in passenger-contacts and in passengers not identified as contacts., Results: Our evaluation included 74 case-travelers on 108 flights. Information for 2673 (79%) of 3399 passenger-contacts was provided to health departments; 9 cases of secondary measles were reported. No additional cases were identified., Conclusion: Our evaluation provided evidence of measles transmission related to air travel. CDC's protocol efficiently identifies passengers most at risk of exposure and infection for flights into and within the United States., (Published by Elsevier Ltd.)

During 2003-2009, substantial progress was made toward the previous goal of measles elimination in the World Health Organization (WHO) European Region (EUR) by 2010. However, since late 2009, measles virus transmission has increased, and outbreaks have become widespread. In 2011, measles outbreaks have been reported in 36 of 53 EUR member states; a total of 26,074 measles cases had been reported regionwide as of October 26. France reported the largest number of cases (approximately 14,000), predominantly among older children and young adults who had not been vaccinated or whose vaccination history was unknown. Overall, the primary reason for the increased transmission and outbreaks of measles in EUR is failure to vaccinate susceptible populations. Eliminating measles by 2015, a new measles elimination target date set in September 2010 by the 60th Regional Committee for Europe, will require 1) increasing demand for and delivery of vaccination to achieve and sustain ≥ 95% coverage with 2 doses of measles-containing vaccine (MCV) across a wide age range, 2) implementing effective outbreak control measures, and 3) further strengthening surveillance to identify cases and outbreaks promptly, and in the future, to validate elimination.

A new strain of measles virus, D4-Hamburg, was imported from London to Hamburg in December 2008 and subsequently spread to Bulgaria, where an outbreak of >24,300 cases was observed. We analyzed spread of the virus to demonstrate the importance of addressing hard-to-reach communities within the World Health Organization European Region regarding access to medical care and vaccination campaigns. The D4-Hamburg strain appeared during 2009-2011 in Poland, Ireland, Northern Ireland, Austria, Greece, Romania, Turkey, Macedonia, Serbia, Switzerland, and Belgium and was repeatedly reimported to Germany. The strain was present in Europe for >27 months and led to >25,000 cases in 12 countries. Spread of the virus was prevalently but not exclusively associated with travel by persons in the Roma ethnic group; because this travel extends beyond the borders of any European country, measures to prevent the spread of measles should be implemented by the region as a whole.

Background: In 2002, the World Health Organization (WHO) adopted a goal to eliminate measles in the European Region by 2010. Measles elimination is defined as the interruption of indigenous measles virus (MV) transmission. The molecular epidemiology of MV transmission in the WHO European Region was studied through the investigation of reported cases and outbreaks to monitor the region's progress toward its measles elimination goal., Methods: National and regional laboratories performed molecular characterization of MV detected between 2007 and 2009 in the WHO European Region. To document indigenous transmission and importations into the region, we analyzed genotyping results and epidemiological data on measles outbreaks reported by the member states., Results: Since 2007, MV genotype D6 has not been reported in the WHO European Region, suggesting that its chains of transmission have been interrupted, whereas several other MV genotypes are still circulating. Although several European countries have already interrupted indigenous MV transmission, genotyping showed that 3 endemic MV transmission chains have been reestablished in other countries., Conclusions: The WHO European Region 2010 goal will not be met, as indigenous transmission of MV has not been interrupted. As the region begins to document its process of elimination verification to monitor progress toward the goal, countries will need to ensure that genotyping is performed in all measles outbreaks., (© The Author 2011. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved.)

With improved measles virus (MV) control, the genetic variability of the MV-nucleoprotein hypervariable region (NP-HVR) decreases. Thus, it becomes increasingly difficult to determine the origin of a virus using only this part of the genome. During outbreaks in Europe and Africa, we found MV strains with identical NP-HVR sequences. However, these strains showed considerable diversity within a larger sequencing window based on concatenated MV phosphoprotein and hemagglutinin genes (P/H pseudogenes). In Belarus, Germany, Russia, and the Democratic Republic of Congo, the P/H pseudogenes provided insights into chains of transmission, whereas identical NP-HVR provided none. In Russia, for instance, the P/H pseudogene identified temporal clusters rather than geographical clusters, demonstrating the circulation and importation of independent variants rather than large local outbreaks lasting for several years, as suggested by NP-HVR. Thus, by extending the sequencing window for molecular epidemiology, a more refined picture of MV circulation was obtained with more clearly defined links between outbreaks and transmission chains. Our results also suggested that in contrast to the P gene, the H gene acquired fixed substitutions that continued to be found in subsequent outbreaks, possibly with consequences for its antigenicity. Thus, a longer sequencing window has true benefits both for the epidemiological surveillance of measles and for the better monitoring of viral evolution.

The objective of this study is to estimate the measles reproduction ratio for eight Western European vaccination programmes. Because many plausible age-structured transmission patterns result in a similar description of the observations, it is not possible to estimate a unique value of the reproduction ratio. A method is developed to estimate bounds and confidence intervals for plausible values of the reproduction ratios using maximum likelihood methods. Lower and upper bounds for plausible values of the basic reproduction ratio are estimated to be 7.17 (95% CI 7.14-7.20) and 45.41 (95% CI 9.77-49.57), corresponding to lower and upper bounds on critical vaccine coverage of 86.6% and 98.1%. Of the eight evaluated vaccination programmes, four have vaccine coverage below the lower bound and allow measles to persist, and four have vaccine coverage at the upper bound and may eventually eliminate measles.

In the period 1980-1981, two hundred nine imported measles cases were reported in the United States. These cases represent 1.3% of the total of 16,630 cases of measles reported to the Centers for Disease Control (CDC) during that period. An average of two imported measles cases were reported each week. The travelers with imported measles were United States citizens and foreign nationals who arrived from 47 different countries throughout the world. However, returning United States citizens have accounted for a rising proportion of imported measles cases. Approximately half (49.3%) of the imported cases were reported by four areas: California, New York State exclusive of New York City, New York City, and Florida. Seven measles outbreaks occurring following importations during the two-year period were identified. In addition to 114 imported measles cases reported to the CDC in 1981, 437 measles cases were reported to be caused directly or indirectly by those importations. The actual number of import-associated cases may have been considerably higher. Imported measles and associated cases together accounted for at least 17% (551/3,124) of reported measles cases in 1981.