Genetic variability of wild-type measles viruses, circulating in the Russian Federation during the implementation of the National Measles Elimination Program, 2003–2007

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.

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.

Measles

Measles is an infectious disease in humans caused by the measles virus (MeV). Before the introduction of an effective measles vaccine, virtually everyone experienced measles during childhood. Symptoms of measles include fever and maculopapular skin rash accompanied by cough, coryza and/or conjunctivitis. MeV causes immunosuppression, and severe sequelae of measles include pneumonia, gastroenteritis, blindness, measles inclusion body encephalitis and subacute sclerosing panencephalitis. Case confirmation depends on clinical presentation and results of laboratory tests, including the detection of anti-MeV IgM antibodies and/or viral RNA. All current measles vaccines contain a live attenuated strain of MeV, and great progress has been made to increase global vaccination coverage to drive down the incidence of measles. However, endemic transmission continues in many parts of the world. Measles remains a considerable cause of childhood mortality worldwide, with estimates that >100,000 fatal cases occur each year. Case fatality ratio estimates vary from <0.01% in industrialized countries to >5% in developing countries. All six WHO regions have set goals to eliminate endemic transmission of MeV by achieving and maintaining high levels of vaccination coverage accompanied by a sensitive surveillance system. Because of the availability of a highly effective and relatively inexpensive vaccine, the monotypic nature of the virus and the lack of an animal reservoir, measles is considered a candidate for eradication.

Molecular epidemiology of measles virus in Italy, 2002-2007

Background

The European Regional Office of the World Health Organization (WHO/Europe) developed a strategic approach to halt the indigenous transmission of measles in its 53 Member States by 2015. In view of the goal of measles elimination, it is of great importance to assess the circulation of wild-type measles virus (MV). Genetic analysis is indispensable to understand the epidemiology of measles.

Methods

Urine and saliva samples were collected between May 2002 and December 2007, in order to find the origins and routes of wild type measles virus circulation. RT-PCR was performed on a total of 414 clinical samples of patients from different Italian regions. The results confirmed the genome presence in 199 samples, out of which 179 were sequenced. The sequences were genotyped by comparing the fragment coding for the carboxyl terminus of the nucleoprotein (450 nucleotides) with that one of the WHO reference strains.

Results

From the year 2002 to the year 2007 phylogenetic analysis of measles sequences showed a predominant circulation of the D7 genotype in the Italian territory for the years 2002–2004. This genotype was replaced by D4 and B3 genotypes in the biennium 2006–2007. During the same period C2, A, D5 and D8 genotypes were also detected.

Conclusions

Genetic characterization of wild-type MV provides a means to study the transmission pathways of the virus, and is an essential component of laboratory-based surveillance. Knowledge of currently circulating measles virus genotype in Italy will help in monitoring the success of the measles elimination programme and will contribute to evaluate the effectiveness of future vaccination campaigns.

Genetic characterization of measles viruses that circulated in Thailand from 1998 to 2008

During the period between 1998 and 2008, 48 representative measles viruses (MeVs) circulating in Thailand were subjected to genetic characterization. Three genotypes, G2, D5, and D9 were detected. The results suggested that measles genotype D5, which has been circulating since at least 1998, is the endemic genotype in Thailand. Genotype G2 was detected between 1998 and 2001. In addition, almost all of the MeVs detected throughout the country in 2008 were genotype D9. This is the first report of genotype D9 in Thailand. This report provides important baseline data about measles genotypes in Thailand and this information will be needed to help verify measles elimination in Thailand.

Molecular epidemiology of measles virus in Iran 2009-2010: first detection of measles genotype H1

Measles virus (MV) genotyping is an important component of measles surveillance in the context of monitoring immunization program effectiveness and documenting MV elimination. The molecular epidemiology and genetic variability of circulating MV strains in Iran during the 2009-2010 were studied in consecutive MV isolates from throat swab and urine. Sequence information obtained from 41 cases based on the 456 nucleotides of the most variable region of the C-terminal part of the N-protein revealed that these sequences belonged to two different genotypes. This is the first description of the genetic characterization of sporadic MV genotype H1 cases in northern Iran. Cases were probably linked to MV importation from distant parts of Asia. The genotype H1 has not been detected in the Eastern Mediterranean Region. In addition, both sequence analysis and epidemiologic data indicated that the more recently detected genotype D4 viruses in Iran were related very closely to viruses that were detected in Pakistan, suggesting that these viruses may have been imported from Pakistan. J. Med. Virol. 83:2200-2207, 2011. © 2011 Wiley Periodicals, Inc.

Molecular epidemiology of measles in India, 2005-2010

Measles is a childhood disease that causes great morbidity and mortality in India and worldwide. Because measles surveillance in India is in its infancy, there is a paucity of countrywide data on circulating Measles virus genotypes. This study was conducted in 21 of 28 States and 2 of 7 Union Territories of India by MeaslesNetIndia, a national network of 27 centers and sentinel practitioners. MeaslesNetIndia investigated 52 measles outbreaks in geographically representative areas from 2005 through June 2010. All outbreaks were serologically confirmed by detection of antimeasles virus immunoglobulin M (IgM) antibodies in serum or oral fluid samples. Molecular studies, using World Health Organization (WHO)-recommended protocols obtained 203 N-gene, 40 H-gene, and 4 M-gene sequences during this period. Measles genotypes D4, D7, and D8 were found to be circulating in various parts of India during the study period. Further phylogenetic analysis revealed 4 lineages of Indian D8 genotypes: D8a, D8b, D8c, and D8d. This study generated a large, countrywide sequence database that can form the baseline for future molecular studies on measles virus transmission pathways in India. This study has created support and capabilities for countrywide measles molecular surveillance that must be carried forward.

Molecular genotyping and epidemiology of measles virus transmission in the World Health Organization European Region, 2007-2009

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.

Revealing new measles virus transmission routes by use of sequence analysis of phosphoprotein and hemagglutinin genes

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.

Comparison of laboratory diagnostic methods for measles infection and identification of measles virus genotypes in Hong Kong

The sensitivities of IgM detection, virus isolation, and RT-PCR for the diagnosis of measles infection were assessed using samples collected from confirmed measles cases from 2006 to 2009. The optimal timing of specimen collection and the preferred specimen type(s) for these tests were also determined. IgM detection showed highest sensitivity when serum samples were collected >or=5 days after rash onset. Virus isolation gave the highest sensitivity when samples were collected <or=3 days after rash onset, with nasopharyngeal aspirate being the best specimen type, followed by urine and throat/combined throat and nasal swab. The highest RT-PCR positive rate (81.0%) was obtained with serum samples collected <or=3 days after rash onset. RT-PCR positive rate of 100% was observed with throat/combined throat and nasal swab, urine and nasopharyngeal aspirate collected <or=16, 4-16, and 4-7 days after rash onset, respectively. The genotype of each measles case was confirmed by sequencing. It was shown that the predominant measles viruses detected in Hong Kong during 2006-2009 belonged to genotype H1 (subtype a) and these strains were related closely to those detected in China.