DNA tracking used to track spread of TB

Scientists are reconstructing the spread of diseases such as tuberculosis using DNA sequencing in order to quickly identify the origin and movement of pathogens.

According to scientists from the Society for General Microbiology's Autumn Conference at the University of Warwick, the approach helps to inform public health strategies on how to control infectious disease outbreaks.

Scientists at the British Columbia Centre for Disease Control in Vancouver, Canada, are using whole-genome sequencing to analyze the bacterial DNA in samples from infected individuals in a TB outbreak. Through the process, they could find where it started and who infected whom, allowing them to identify key persons, places and behaviors that helped spread the disease.

Previous research techniques analyzed only some of the DNA in infected samples, which did not provide enough information on how the pathogen spread.

"Solving' an outbreak - identifying the source of the disease and the underlying patterns of transmission - is the proverbial holy grail of epidemiology," lead researcher Dr. Jennifer Gardy said. "Using whole-genome sequencing we are now able to act like field naturalists and observe how pathogens behave out in the wild. We can see where outbreaks start and how they spread. This level of insight has never been seen before and it promises to change the way we do public heath outbreak investigations."

The group is now seeing how different social settings and community structures effect the spread of the disease.

"We are discovering how important location-based transmission is, and that identifying and screening individuals who visited these locations are integral to outbreak management," Grady said. "We hope to build a 'pathogen knowledge base' that describes how different communicable diseases spread in different social and environmental settings. From this we will be able to identify commonalities that can be targeted in global public health interventions."

Public health officials are putting this new knowledge to use in public health policy and practice.

"As frontline public health practitioners we are using whole-genome sequencing to answer pressing questions. We are able to take our research findings and translate them into clinical action in the short term. With better control and prevention programs, we can ultimately reduce the burden of certain infectious diseases," Gardy said.