The use of molecular techniques such as DNA typing has transformed epidemiologic investigation by making it possible to trace precisely the path taken by a specific strain of an infectious pathogen, such as the gonococcus, as it passes from one host to another. DNA/RNA typing is also an essential part of genetic epidemiology; it can help to identify cancer-prone family lineages, for example. Molecular techniques are used in cancer epidemiology to identify precancerous changes in studies of environmentally and occupationally induced cancers. In short, molecular methods are a powerful tool in many aspects of observational and analytic epidemiology.
JOHN M. LAST