July 07, 2015
Vancouver, BC- Following the 2010 Olympics Winter Games, there has been a resurgence in measles in British Columbia. In 1998, measles was declared eradicated in Canada; however, since reaching a worldwide historic low in 2008, the incidence of measles has been on the rise in almost every World Health Organization (WHO) region.
While vaccination is the best protection against contracting measles, there is little known about the spread of the virus. An unexpected measles outbreak immediately following the 2010 Olympics presented researchers from the British Columbia Centre for Disease Control (BCCDC) and the University of British Columbia with a unique opportunity to study the virus’ transmission in more detail. In fact, genetic analysis revealed that there wasn’t just one outbreak to assess, but rather two distinct outbreaks, caused by measles virus genotypes H1 and D8.
Although the WHO does recognize that the spread of the virus is often associated with large public gatherings, person-to-person transmission has been difficult to assess through traditional epidemiological information (e.g. based on information such as relationships, physical proximity) alone because many cases have no identifiable link to other cases. Leveraging funds from Genome British Columbia (Genome BC), Dr. Jennifer Gardy and team conducted the first genomic epidemiology investigation of this re-emerging virus using whole genome sequencing (WGS) to explore potential transmission routes.
The team was able to sequence 27 complete genomes from both H1 and D8 genotype measles viruses, making this the biggest measles genomics effort to date. Interestingly, they found that while the H1 virus spread across BC, the D8 outbreak remained restricted to Vancouver, and that all the northern BC cases arose from a single introduction, likely from a person travelling along Highway 97.
“This is the first time genomics has been used to reconstruct a measles outbreak and our work shows that it really has the potential to shed light on how these outbreaks happen,” said Dr. Jennifer Gardy, Senior Scientist, BCCDC Communicable Disease Prevention and Control Services and Assistant Professor, University of British Columbia. “In fact, similar genomic analysis is being done in the West African Ebola outbreak right now, and is helping researchers there understand how the virus is moving across borders.”
“With more genomic DNA from outbreak samples in the future, whether they be measles or a new emerging threat, we can build better maps of how these viral outbreaks start and spread. Better maps give us a better chance of not only stopping current outbreaks, but also preventing future ones,” noted Gardy.
The findings of this study are to be published in The Journal of Infectious Disease.
“Genomic research has had a significant impact on the understanding of infectious disease,” says Dr. Alan Winter, President and CEO of Genome BC. “As identified in Genome BC’s Strategic Plan, we believe there is an opportunity to leverage genomics to positively impact the management of population-based infectious disease outbreaks by public health and medical practitioners in BC and beyond. We’re proud to be funding world class research in this area.”
The relatively small and often rapidly evolving genomes of infectious agents make them eminently suitable to genomic approaches for understanding the basis of their pathogenesis, their modes of transmission, and their susceptibility to treatment. The more we understand what is happening at a molecular level, the better we can tailor our strategies for prevention and treatment.
The framework for this type of study was based on previous research conducted on an outbreak of tuberculosis (TB) in a BC community. Funded by Genome BC and published in the New England Journal of Medicine, researchers from BCCDC, Canada’s Michael Smith Genome Sciences Centre and Simon Fraser University used whole genome sequencing to discern subtle genetic differences between different bacterial strains. These slight genetic differences allowed the researchers to identify not only where the outbreak organism had originated, but also how it had moved throughout the community. These findings offered a significant advance and enabled better public health prevention and detection strategies.
“Genome BC’s support has really allowed us to push the boundaries of traditional public health laboratory work and try new things. Our team was the first to reconstruct a TB outbreak with genome sequencing and now we’ve done the same for measles,” notes Gardy. “We’re seeing groups around the world using similar approaches to study outbreaks in their backyards. It’s really a revolution in public health – it’s exciting to see how this approach is being used.
