Pathogen identification , or diagnostic capacity, is often the rate-limiting step in infectious disease detection. Although many bacteria an d some other pathogens can be identified by tradition al methods such as morphology and growth characteristics, this requires suitably equipped labor atories with trained personnel and can take days or weeks. Viruses can be especially challenging. Until recently, the ability to identify new or uncultivatible pathogens was therefore severely limited . The use of new molecular methods , such as genomic, or ‘‘deep,’’ sequencing, nucleic acid arrays, and various adaptations of the polymerase chain reaction (PCR ) for conserved sequences shared by a viral or microbial group, now allow potential identification even of unknown
pathogens based on commonalities with known related organisms.47,48 This open-ended identification of pathogens has been termed ‘‘pathogen discovery.’’ It was made possible by the impressive evolution of both molecular diagnostic methods and biomedical informatics (in part enabled by enormous advances in computing power), providing the ability to separate potential microbial signal from background noise.47