The role of pathogen genomics in assessing disease transmission.

Whole genome sequencing (WGS) of pathogens enables the sources and patterns of transmission to be identified during specific disease outbreaks and promises to transform epidemiological research on communicable diseases. This review discusses new insights into disease spread and transmission that have come from the use of WGS, particularly when combined with genomic scale phylogenetic analyses. These include elucidation of the mechanisms of cross species transmission, the potential modes of pathogen transmission, and which people in the population contribute most to transmission. Particular attention is paid to the ability of WGS to resolve individual patient to patient transmission events. Importantly, WGS data seem to be sufficiently discriminatory to target cases linked to community or hospital contacts and hence prevent further spread, and to investigate genetically related cases without a clear epidemiological link. Approaches to combine evidence from epidemiological with genomic sequencing observations are summarised. Ongoing genomic surveillance can identify determinants of transmission, monitor pathogen evolution and adaptation, ensure the accurate and timely diagnosis of infections with epidemic potential, and refine strategies for their control. © BMJ Publishing Group Ltd 2015.