Measles Virus Genotypes Research Articles

Measles Vaccine-Associated Rash Illness in China: an Emerging Issue in the Process of Measles Elimination.

Along with the implementation of measles case-based surveillance, measles vaccine-associated rash illness (VARI) cases were detected in China. To better understand the characteristics of VARI, 101 VARI cases confirmed by measles virus genotyping in 2011 to 2018 were analyzed in this study. With the decrease in measles incidence, the detection rate of VARI cases increased among the cases confirmed by genotyping. Compared with genotype H1 wild-type measles, VARI occurred throughout the year, without obvious seasonal distribution. Infants and children of ages 8 to 23 months were the main population of VARI. VARI mainly occurred within 14 days after measles vaccination. The number of VARI cases peaked on the 8th day after measles vaccination, which was later than that of genotype H1 wild-type measles cases with a measles vaccination history. VARI presents clinical symptoms similar to those of measles. The frequencies of the "3Cs" (cough, coryza, and conjunctivitis), Koplik spots, and complications in VARI cases were significantly lower than those in wild-type measles cases. In total, 94.06% of sequences from VARI cases were identical to measles vaccine strain S191 in the C-terminal 450-nucleotide sequence of the nucleoprotein (N-450) gene. A few substitutions were found in N-450 sequences of the VARI cases. The confirmation of VARI has become an emerging issue in the process of measles elimination. Rapid confirmation of VARI is critical for measles surveillance and will help to determine the response measures for measles, especially in measles preelimination and elimination settings. The suspected measles cases with measles-containing vaccine (MCV) vaccination were recommended to be tested by the laboratory to identify wild-type measles or VARI.

Imported B3 genotype measles virus isolated in Fujian province

Objective: We isolated and identified the genotypes and molecular characteristics of the imported B3 measles virus (MeV) in Fujian province in 2018. Methods: Throat swab specimens were collected from clinically diagnosed measles patients and tested for viral RNA, using the real-time reverse transcription-polymerase chain reaction after the RNA extraction. Reverse transcription-polymerase chain reaction method was undertaken to amplify the 634 nucleotide acids of 3-terminal of the nucleoprotein gene. A phylogenetic tree was constructed and similarities in homology assessed. Results: We successfully isolated and obtained two measles virus strains and eighteen viral nucleic acid sequences. The Fujian strains were clustered within the same genotype group of WHO genotype B3 reference strains. Compared to the major circulating measles strain genotype B3 in the world, two Fujian strains MV18-41 and MV18-42 showed 100.0% nucleic acid homology to HongKong.CHN/35.18 strain which was isolated from Hong Kong in 2018. The remaining 16 Fujian strains showed the highest homology (99.9%) with the Mvs/Osaka.JPN/38.18/B3 strain isolated from Japan in 2018. Compared with other 23 WHO genotype reference strains, homology on both nucleotide and amino acid of the Fujian strain and the B1 genotype reference strain were the smallest, as 95.1%-95.4% and 95.3%, respectively. The differences of homology between the Fujian strain and H1 genotype reference strain were the largest, as 88.7%-89.0% and 87.3%, respectively. In addition, there were 13 mutation sites between the Fujian strain and the vaccine strain (Shanghai-191) at the 150 amino acid position of carboxy terminus on N protein, However, these sites did not cause functional changes in the protein region. Conclusions: In Fujian province, two strains of B3 genotype measles virus were obtained successfully, which were considered to be new genotype measles virus found in 2018. These findings showed it is necessary to strengthening the monitoring program on imported cases for better control and eliminate the measles virus.

Molecular genetic analysis of the strain Leningrad-16 used for the production of measles vaccine

Aim. To study the genetic stability of the measles virus strain Leningrad-16 (L-16) used for the production of vaccine at JSC NPO Mikrogen.Materials and methods. A series of production and sowing strains of L-16 (JSC NPO Mikrogen), ready-made series of measles vaccines from various manufacturers, and the strain of measles virus genotype D6 were studied. Molecular genetic study of the strains was performed using RT-PCR followed by restriction analysis and sequencing.Results. The complete genome sequences of the production and sowing strains of L-16 that are used for vaccine production were obtained. The sequence of the vaccine strain was deposited in GenBank. Strain L-16 was confirmed to be genetically stable. The obtained data demonstrated the possibility of using the RT-PCR method with subsequent restriction analysis to confirm the authenticity of the vaccine strain L-16 in finished mono and three component vaccines.Conclusion. The results of the study suggest the applicability of the molecular genetic methods to confirm the authenticity of the studied strains not only at the production stages, but also in the finished series of vaccines.

Measles Virus Imported by International Traveler in Jiangsu Province of China, in 2018 and 2019.

Measles remains a public health concern in many regions, and the imported measles cases continue to challenge the measles elimination program for most of the countries where measles was verified to be eliminated or approaching elimination. The imported measles cases have been reported since October, 2017, in Jiangsu province, China. In this study, we reported the first imported B3 genotype measles virus from Egypt and the second imported D8 genotype measles virus from Philippines through international traveling. No secondary measles cases were found after these imported cases. Our findings highlighted the importance of measles vaccination targeting international travelers in China.

Measles Virus Infection and Immunity in a Suboptimal Vaccination Coverage Setting.

Despite efforts to improve surveillance and vaccination coverage, measles virus (MeV) continues to cause outbreaks also in high-income countries. As the reference laboratory of the Veneto Region, Italy, we analyzed changes in population immunity, described measles outbreaks, investigated MeV genetic diversity, and evaluated cross-protection of measles vaccination against MeV epidemic strains. Like most European areas, the Veneto Region has suboptimal measles vaccination coverage and is facing a growing public mistrust of vaccination. A progressive decline of measles vaccine uptake was observed during the last decade in the Veneto Region, leading to immunity gaps in children and young adults. Measles outbreaks were caused by the same MeV genotype B3, D4, and D8 strains that were circulating in other European countries. Eleven cases of measles were observed in immunized subjects. These cases were not associated with particular MeV genotypes nor with mutations in epitopes recognized by neutralizing antibodies. Accordingly, sera from fully vaccinated subjects cross-neutralized epidemic MeV strains, including the genotypes B3, D4, and D8, with the same high efficiency demonstrated against the vaccine strain. In fully vaccinated subjects, high MeV IgG antibody titers persisted up to 30 years following vaccination. These results support the use of the current measles-containing vaccines and strategies to strengthen vaccination.

Molecular characterization of measles virus strains circulating in Cameroon during the 2013-2016 epidemics.

The first genotyping data on measles virus (MeV) strains in Cameroon dates from 1994, while other studies were realized in 2001 and 2011 with the establishment of MeV virological surveillance. However, the genetic data of MeV strains circulating in Cameroon remains fragmented and concentrated in certain regions, hence the need for an update. The objective of this study was to have recent data on MeV genotypes circulating in Cameroon. Ninety throat swabs collected during recent measles outbreaks were analyzed by MeV genotyping RT-PCR using the nucleoprotein gene N. The resulting sequences were analyzed on the basis of 450 nucleotides with MEGA 7 software. Overall genome analysis was performed on 40/90 sequences. The strains were from all ten regions and all belonged to cluster 1 of genotype B3. The genotype B3 has been circulating in Cameroon for long periods of time; efforts must be made in immunization for its elimination.

Biophysical characterization and single-chain Fv construction of a neutralizing antibody to measles virus.

The measles virus (MV) is a major cause of childhood morbidity and mortality worldwide. We previously established a mouse monoclonal antibody, 2F4, which shows high neutralizing titers against eight different genotypes of MV. However, the molecular basis for the neutralizing activity of the 2F4 antibody remains incompletely understood. Here, we have evaluated the binding characteristics of a Fab fragment of the 2F4 antibody. Using the MV infectious assay, we demonstrated that 2F4 Fab inhibits viral entry via either of two cellular receptors, SLAM and Nectin4. Surface plasmon resonance (SPR) analysis of recombinant proteins indicated that 2F4 Fab interacts with MV hemagglutinin (MV-H) with a KD value at the nm level. Furthermore, we designed a single-chain Fv fragment of 2F4 antibody as another potential biopharmaceutical to target measles. The stable 2F4 scFv was successfully prepared by the refolding method and shown to interact with MV-H at the μm level. Like 2F4 Fab, scFv inhibited receptor binding and viral entry. This indicates that 2F4 mAb uses the receptor-binding site and/or a neighboring region as an epitope with high affinity. These results provide insight into the neutralizing activity and potential therapeutic use of antibody fragments for MV infection.

Nationwide Molecular Epidemiology of Measles Virus in Japan Between 2008 and 2017.

Genotyping evidence that supports the interruption of endemic measles virus (MV) transmission is one of the essential criteria to be verified in achieving measles elimination. In Japan since 2014, MV genotype analyses have been performed for most of the measles cases in prefectural public health institutes nationwide. With this strong molecular epidemiological data, Japan was verified to have eliminated measles in March, 2015. However, even in the postelimination era, sporadic cases and small outbreaks of measles have been detected repeatedly in Japan. This study investigated the nationwide molecular epidemiology of MV between 2008 and 2017. The 891 strains in the total period between 2008 and 2017 belonged to seven genotypes (D5, D4, D9, H1, G3, B3, and D8) and 124 different MV sequence variants, based on the 450-nucleotide sequence region of the N gene (N450). The 311 MV strains in the postelimination era between 2015 and 2017 were classified into 1, 7, 8, and 32 different N450 sequence variants in D9, H1, B3, and D8 genotypes, respectively. Analysis of the detection period of the individual N450 sequence variants showed that the majority of MV strains were detected only for a short period. However, MV strains, MVs/Osaka.JPN/29.15/ [D8] and MVi/Hulu Langat.MYS/26.11/ [D8], which are named strains designated by World Health Organization (WHO), have been detected in many cases over 2 or 3 years between 2015 and 2017. The WHO-named strains have circulated worldwide, causing outbreaks in many countries. Epidemiological investigation revealed repeated importation of these WHO-named strains into Japan. To demonstrate the elimination status (interruption of endemic transmission) in situations with repeated importation of the same strains is challenging. Nevertheless, the detailed sequence analysis of individual MV strains and chronological analysis of these strains provided sufficient evidence to show that Japan has still maintained its measles elimination status in 2017.

Molecular characterization of measles viruses in China: Circulation dynamics of the endemic H1 genotype from 2011 to 2017.

Due to the Expanded Program on Immunization (EPI) and supplementary immunization activities (SIAs) in China, the incidence of measles in China has decreased extensively. The incidence reached its lowest levels in contemporary history in 2012 and 2017, with incidence rates of 4.6 and 4.3 per million population, respectively. However, more than 147,000 measles cases were reported from 2013 to 2016. Furthermore, the proportions of cases in infants < 8 months and adults have been increasing since 2013, representing a considerable challenge for measles elimination in China. A total of 14,868 measles viruses were isolated from confirmed measles cases from 2011 to 2017, of which 14,631 were identified as the predominant endemic genotype, H1; 87 were identified as genotype A viruses that were vaccine associated strains; and 150 were identified as non-H1 genotype viruses. The non-H1 genotype viruses included 62 D8 viruses, 70 D9 viruses, 3 D11 viruses, 14 B3 viruses, and 1 G3 virus, which were identified as imported or import-related viruses that caused sporadic cases or small outbreaks. Most of the transmission chains detected during the period 2011–2012 were interrupted and were followed by many new transmission chains of unknown origin that spread, causing a large measles resurgence in China during 2013–2016. After 4 years of measles resurgence and continuous implementation of the routine immunization program and SIAs, the population immunity reached a sufficiently high level to interrupt most of the transmission chains; only a few strains survived, which continued to be sporadically detected in China in 2017. In the present study, the results from the combined epidemiological and molecular virological data demonstrated the great progress towards measles elimination in China by the further analysis of circulation dynamics for the endemic H1 genotype measles virus from 2011 to 2017. And this study accumulated critical baseline data on circulating wild-type measles viruses in China and provides comprehensive information to the world. These comprehensive baseline data provide evidence to support measles elimination in the future, not only in China but also in other countries worldwide. In addition, the information will be very useful to other countries for tracing their sources of measles cases and for identifying transmission links, which can help prevent potential measles outbreaks.

Laboratory-based investigation of fever with rash cases in the Maharashtra State - India, 2014 to 2017.

The Maharashtra State (MS), India, launched measles surveillance in the year 2013. From 2014 to 2017, specimens from the patients presenting with fever and skin rashes were received at the National Institute of Virology, Pune. From 36 districts of the MS, 2795 cases (1428 males and 1367 females) were referred for the laboratory diagnosis of measles and rubella using immunoglobulin M enzyme immunoassay and/or RT-PCRs. The majority of the cases (93.3%, n = 2609) were under 15 years of age. About 17.7% (494) cases had a history of measles immunization (one dose) during their childhood. Virus isolation was attempted from 107 throat swabs and 84 urine samples obtained from 191 cases using Vero hSLAM cells. The results confirmed measles in 1756 and rubellain 282 fever with rash cases by serological and molecular tools. Precisely, 170 of 382 and 35 of 149 specimens were positive for measles and rubella RT-PCRs, respectively. Sequencing of the representative PCR products showed the circulation of measles virus genotypes D4 (n = 26) and D8 (n = 107), and rubella virus genotype 2B (n = 1). Twenty-three measles viruses were isolated and genotyped, of which, 6 were D4 and 17 were D8 genotypes. Amongst the measles-immunized individuals, 51.2% (253/494) had laboratory-confirmed measles. Overall, 72.9% fever with skin rash cases (n = 2038) from the MS was laboratory confirmed for either measles or rubella. The contribution of measles was higher than rubella in the fever with rash cases. As expected, more fever with rash cases were documented in children compared with adults and highlighted the need to increase measles-rubella immunization coverage.

Global spatiotemporal transmission dynamics of measles virus clade D genotypes in the context of the measles elimination goal 2020 in India

Measles viruses (MeV) circulating in India mainly belong to genoypes D4 and D8 of clade D. In the context of measles elimination goal 2020 in India, molecular clock and phylogeography studies would help to identify the timescales of evolution and track the transmission pathways of MeV. We used nucleoprotein gene sequences (n = 756) from GenBank, representing 86 countries (1973–2016), to study the spatiotemporal transmission dynamics of clade D. Genotype D4 was introduced into India around 1991 and genotype D8 around 1994. Recent transmissions of the D4 genotype of measles virus (MeV) were noted from India to the United States of America and East Asia region while D8 genotype importations from North America were noted in recent years.

Measles virus genotype D4 strains with non-standard length M-F non-coding region circulated during the major outbreaks of 2011-2012 in Spain.

In recent decades, vaccination has substantially reduced the number of measles cases to levels close to the elimination stage. However, major measles outbreaks occurred in Europe during 2010–2012, after the introduction of the D4-Enfield lineage. We have performed a molecular characterization of 75 measles virus genotype D4 strains from patients infected in Spain between 2004 and 2012 by sequencing the N-450 region and the M-F non-coding region (M-F NCR) in order to identify genetic features of these viruses. The analysis of the N-450 region confirmed that all samples obtained since 2008 belonged to variants or sets of identical sequences of the D4-Enfield lineage, including a new one named MVs/Madrid.ESP/46.10/. Analysis of the M-F NCR showed insertions and deletions associated with previously described, uncommon non-standard genome length measles viruses. This genetic feature was identified in the D4-Enfield lineage viruses, but not in the other D4 viruses that were circulating in Spain before 2008, suggesting that these non-standard length M-F NCR sequences are characteristic of the D4-Enfield lineage. The results of the phylogenetic analysis of Spanish M-F NCRs suggest higher resolution in discriminating strains than did the N-450 analysis. In addition, the results of the analysis of the M-F NCR on the MVs/Madrid.ESP/46.10/ sub-lineage seem to support the potential utility of this region as a tool for epidemiological surveillance complementary to the N-450 region, as previously suggested. Further investigation on this question, as well as the surveillance of new potentially emerging strains with non-standard length M-F NCR are strongly recommended as part of future strategies for measles elimination.

Epidemiological Outbreaks of Measles Virus in Kazakhstan during 2015.

This study involved epidemiological surveillance of the measles virus (MV) in the territory of the Republic of Kazakhstan during 2015-2016. We detected MV genotype D8 in this season of measles outbreak. A total of 2,341 cases were registered and 19 were identified by genotyping. Sixteen of these samples were attributed to subgroup A of genotype D8, while 3 imported cases were represented by genotypes B3 and H1. Analysis of vaccination coverage showed that a large group of infected people were not vaccinated or did not have a reliable report on their vaccination status. This issue might increase the morbidity rate among the healthy population in outbreak seasons. To prevent the incidence caused by this problem, we have successfully introduced epidemiologic measures for the control of measles.

Measles Outbreak in Sverdlovsk Region

Objective.In the Russian Federation on the background of the sporadic incidence of measles, the trend is not highly uniform distribution of morbidity on territories of the country with the formation of local outbreaks, including the result of nosocomial infection. Find out the causes of the outbreak, for example the territory, for 15 years keeping and epidemic well-being in relation to measles, high vaccination coverage in children and adults, to assess the capacity of health care organizations and epidemiology to prevent the spread of measles and the elimination of flash was the goal of this research.Material and methods. A retrospective epidemiological analysis was held: the incidence of measles for the period 2001–2016 in the Sverdlovskiy region ; 76 «Cards epidemiological case investigation suspected measles», was from October to December 2016; the analysis of the extraordinary and final reports of the measles outbreak, reports on the activities carried out in the outbreak of measles. Laboratory verification of cases suspected were examined the ELISA method in the Perm regional centre, on the basis of detection of specific IgM and/or IgG increase. Molecular genetic research of 15 clinical specimens were performed at the Scientific- methodical centre on supervision of measles and rubella (Gabrichevsky Research Institute by Epidemiology &amp; Microbiology», Moscow).Results.During the period c from 40 to 51 week of 2016 measles ill 76 people, mostly (66 persons) residents of the city of Yekaterinburg. Prevailed among the infected children was 67% (51 persons), usually not vaccinated against this infection – 90% (46) of children had a measles vaccination. All cases were laboratory confirmed. Expected sources or place of infection was established in 90.8% of cases. Among cases and 72.4% (55 persons) amounted to unvaccinated against measles, 11.8 per cent(9 people) were vaccinated once, of 15.8% (12) had a two-fold vaccination. In 8 hospitals was 8 foci of measles, 6 of which had spread. Among the cases of measles identified in health facilities, 35 children and 19 adults, including 5 health workers and 3 medical students. The formation of foci of nosocomial infection contributed to missed cases of measles, late diagnosis, significantly reduce the effectiveness of anti-epidemic measures. The results of molecular genetic studies of 15 clinical samples of patients selected at 42–44, and 47–49 weeks possible to establish the circulating strains of measles virus genotype D8. Epidemiological investigations and the common genetic variant circulating genotypes, selected at different stages of measles spread from different foci made it possible to combine all cases in one outbreak. Analysis of clinical manifestations of measles have testified to the fact that measles is proceeded typically in 92.2% of cases. Eleven drifts infection in educational institutions of Ekaterinburg was not accompanied by the secondary spread, indicating good collective immunity.Conclusion.Thus, a retrospective epidemiological analysis of outbreaks of measles showed that in conditions of sporadic measles in doctors reduced vigilance against measles. Late diagnosis of measles and as a consequence of its failure to carry out anti- epidemic measures led to the spread of infection, as well as skid measles in other medicine organization, which consisted of nosocomial foci. The present outbreak showed that measles requires constant attention, especially during her long absence in the region. It is only possible to prevent sustained secondary transmission if measles vaccination coverage is high for the entire population.

Investigation of a measles outbreak caused by genotype D8 virus in Pinghu city of Zhejiang province, 2017

Objective: To investigate the epidemiological characteristics of measles outbreak caused by genotype D8 virus in Pinghu city of Zhejiang province, and provide evidence for the control of the outbreak. Methods: The measles outbreak data were collected through National Measles Surveillance System. The outpatient records and admission records were checked, field investigation and outbreak response were conducted. Blood samples in acute phase and swab specimens were collected from the patients for laboratory testing, including serology test, RNA extraction and amplification, measles virus isolation and genotype identification. Software SPSS 17.0 and Excel 2016 were used for data analysis. Results: A total of 10 confirmed measles cases were reported in Pinghu city, and 8 cases were aged >40 years. Six blood samples were collected, in which 5 were measles D8 virus positive and 1 was negative in measles virus detection. There were epidemiological links among 10 cases which occurred in a factory, a hospital and a family at the same time. There was no statistical difference in symptoms among cases caused by D8 virus and H1a virus. After the emergent measles vaccination, the measles outbreak was effectively controlled. Conclusion: Untimely response due to the uneasy detection of measles cases in the early stage, nosocomial infection and weak barrier of measles immunity in adults might be the main reasons for this outbreak. Measles vaccination is effective in the prevention of measles D8 virus infection. It is necessary to strengthen measles genotype monitoring for the tracing of infection source and control of outbreaks.

Hemagglutinin-specific neutralization of subacute sclerosing panencephalitis viruses.

Subacute sclerosing panencephalitis (SSPE) is a progressive, lethal complication of measles caused by particular mutants of measles virus (MeV) that persist in the brain despite high levels of neutralizing antibodies. We addressed the hypothesis that antigenic drift is involved in the pathogenetic mechanism of SSPE by analyzing antigenic alterations in the MeV envelope hemagglutinin protein (MeV-H) found in patients with SSPE in relation to major circulating MeV genotypes. To this aim, we obtained cDNA for the MeV-H gene from tissue taken at brain autopsy from 3 deceased persons with SSPE who had short (3–4 months, SMa79), average (3.5 years, SMa84), and long (18 years, SMa94) disease courses. Recombinant MeVs with a substituted MeV-H gene were generated by a reverse genetic system. Virus neutralization assays with a panel of anti-MeV-H murine monoclonal antibodies (mAbs) or vaccine-immunized mouse anti-MeV-H polyclonal sera were performed to determine the antigenic relatedness. Functional and receptor-binding analysis of the SSPE MeV-H showed activity in a SLAM/nectin-4–dependent manner. Similar to our panel of wild-type viruses, our SSPE viruses showed an altered antigenic profile. Genotypes A, G3, and F (SSPE case SMa79) were the exception, with an intact antigenic structure. Genotypes D7 and F (SSPE SMa79) showed enhanced neutralization by mAbs targeting antigenic site IIa. Genotypes H1 and the recently reported D4.2 were the most antigenically altered genotypes. Epitope mapping of neutralizing mAbs BH015 and BH130 reveal a new antigenic site on MeV-H, which we designated Φ for its intermediate position between previously defined antigenic sites Ia and Ib. We conclude that SSPE-causing viruses show similar antigenic properties to currently circulating MeV genotypes. The absence of a direct correlation between antigenic changes and predisposition of a certain genotype to cause SSPE does not lend support to the proposed antigenic drift as a pathogenetic mechanism in SSPE.

Molecular characterisation of measles virus strains among refugees from Central African Republic in Cameroon in 2014.

Measles is a highly infectious human viral disease caused by measles virus (MeV). An estimated 114 900 measles deaths occurred worldwide in 2014. There are currently eight clades (A-H) comprised 24 MeV genotypes. We sought to characterise MeVs among Central African Republic (CAR) refugees during the 2014 measles epidemic in Cameroon. Samples were collected from children <15 years with suspected measles infections in two refugee camps in the east region of Cameroon. Viral RNA was extracted directly from urine samples. RNA detection of MeV RNA was performed with real-time reverse transcription polymerase chain reaction (PCR) to amplify a 634 bp nucleotide fragment of the N gene. The sequence of the PCR product was obtained to determine the genotype. MeV RNA was detected in 25 out of 30 samples from suspected cases, and among the 25 positive samples, MeV sequences were obtained from 20. The MeV strains characterised were all genotype B3. The MeV strains from genotype B3 found in this outbreak were more similar to those circulating in Northern Cameroon in 2010-2011 than to MeV strains circulating in the CAR in 2011. Surveillance system should be improved to focus on refugees for early detection of and response to outbreaks.

Identification of measles virus genotype B3 associated with outbreaks in Islamabad, Pakistan, 2013-2015.

Measles virus infection remains a significant cause of childhood mortality and morbidity despite continued global efforts and the availability of a safe and effective vaccine. Molecular analysis of indigenous measles viruses could provide critical information on outbreak linkages and transmission pathways that can aid the implementation of appropriate control programs in Pakistan. Blood samples and throat swabs were collected from subjects suspected with measles in Islamabad, Pakistan from 2013 to 2015. Serum samples were tested for the presence of measles immunoglobulin M (IgM) antibodies using enzyme-linked immunosorbent assay (ELISA) while throat swabs were used for the isolation (Vero/SLAM cell line) and subsequent characterization and phylogenetic analysis of measles strains. Of 373 blood samples, 66% tested positive for measles IgM. Male subjects were more often infected (58%) than female (42%) with the highest frequency of positive cases (63%) in the 0-5-years age group. Among the positive cases, only 13% had received one or two doses of the measles vaccine, while 87% were unvaccinated. Of 80 throat swabs, 29 (36%) showed a measles virus-specific cytopathic effect (CPE) and were characterized as genotype B3 through partial sequencing of the nucleoprotein (N) gene. Phylogenetic analysis revealed the Pakistani B3 strains to be closely related to strains from neighboring countries (Iran and Afghanistan) as well as with B3 viruses from the USA, Germany, and the UK. The study results showed that despite the availability of an effective vaccine, the burden of measles infections is very high in Pakistan due to poor routine immunization coverage even in major cities, including the capital city of Islamabad. It is imperative that national health authorities take urgent strategic steps to improve routine immunization and implement adequate molecular identification methods to tackle future measles outbreaks.

Large measles outbreak introduced by asylum seekers and spread among the insufficiently vaccinated resident population, Berlin, October 2014 to August 2015.

The largest measles outbreak in Berlin since 2001 occurred from October 2014 to August 2015. Overall, 1,344 cases were ascertained, 86% (with available information) unvaccinated, including 146 (12%) asylum seekers. Median age was 17 years (interquartile range: 4–29 years), 26% were hospitalised and a 1-year-old child died. Measles virus genotyping uniformly revealed the variant ‘D8-Rostov-Don’ and descendants. The virus was likely introduced by and initially spread among asylum seekers before affecting Berlin’s resident population. Among Berlin residents, the highest incidence was in children aged < 2 years, yet most cases (52%) were adults. Post-exposure vaccinations in homes for asylum seekers, not always conducted, occurred later (median: 7.5 days) than the recommended 72 hours after onset of the first case and reached only half of potential contacts. Asylum seekers should not only have non-discriminatory, equitable access to vaccination, they also need to be offered measles vaccination in a timely fashion, i.e. immediately upon arrival in the receiving country. Supplementary immunisation activities targeting the resident population, particularly adults, are urgently needed in Berlin.

Measles Outbreak with Unique Virus Genotyping, Ontario, Canada, 2015.

The province of Ontario continues to experience measles virus transmissions despite the elimination of measles in Canada. We describe an unusual outbreak of measles in Ontario, Canada, in early 2015 that involved cases with a unique strain of virus and no known association among primary case-patients. A total of 18 cases of measles were reported from 4 public health units during the outbreak period (January 25–March 23, 2015); none of these cases occurred in persons who had recently traveled. Despite enhancements to case-patient interview methods and epidemiologic analyses, a source patient was not identified. However, the molecular epidemiologic analysis, which included extended sequencing, strongly suggested that all cases derived from a single importation of measles virus genotype D4. The use of timely genotype sequencing, rigorous epidemiologic investigation, and a better understanding of the gaps in surveillance are needed to maintain Ontario’s measles elimination status.