DNA tracking of TB outbreaks could identify origin
19 September 2012
Whole-genome sequencing of killer diseases such as
tuberculosis (TB) could reconstruct the spread from person to person and quickly
identify the origin and movement of pathogens, according to research by
the British Columbia Centre for Disease Control (BCCDC).
This approach is directly informing public health strategies to
control infectious disease outbreaks, said Dr Jennifer Gardy, from
BCCDC, speaking at
the Society for General Microbiology’s Autumn Conference at the
University of Warwick earlier this month.
A team from BCCDC in
Vancouver, Canada, used whole-genome sequencing to analyse the
bacterial DNA in samples from 36 of 41 infected individuals in a TB
outbreak. They were able to track the pathogen’s movements through
the community in British Columbia, including where it started and
who infected whom.
From this they could identify key persons,
places, and behaviours that contributed to the spread of disease.
They showed how the social structure of a community contributed to
the rapid spread of TB and that a rise in crack cocaine use in the
area may have triggered the outbreak.
Earlier epidemiological tools analysed some — but not all — of
the DNA in infected samples. This gave too little information to
accurately reconstruct an outbreak and scientists could only make
informed guesses at how a pathogen spread through a population.
Lead researcher Dr Jennifer Gardy, speaking at the conference
said, “‘Solving’ an outbreak — identifying the source of the disease
and the underlying patterns of transmission — is the proverbial holy
grail of epidemiology. 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 currently applying the same reconstruction technique
to a different TB outbreak in a different social setting. “We are
discovering how important location-based transmission is, and that
identifying and screening individuals who visited these locations
are integral to outbreak management,” explained Dr Gardy.
Other research groups are applying this genome-based approach for
outbreak reconstruction to other micro-organisms. “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.”
The work is directly informing public health policy and practice,
said Dr Gardy. “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
programmes, we can ultimately reduce the burden of certain
infectious diseases,” she said.
The Society for General Microbiology’s Autumn Conference 2012