Molecular epidemiology: Focus on infection

Molecular biology techniques have become increasingly integrated into the p ractice of infectious disease epidemiology, The term "molecular epidemiolog y" routinely appears in the titles of articles that use molecular strain-ty ping ("fingerprinting") techniques-regardless of whether there is any epide miologic application. What distinguishes molecular epidemiology is both the "molecular:' the use of the techniques of molecular biology, and the "epid emiology:' the study of the distribution and determinants of disease occurr ence in human populations. The authors review various definitions of molecu lar epidemiology. They then comment on the range of molecular techniques av ailable and present some examples of the benefits and challenges of applyin g these techniques to infectious agents acid their affected host using tube rculosis and urinary tract infection as examples. They close with some thou ghts about training future epidemiologists to best take advantage of the ne w opportunities that arise from integrating epidemiologic methods with mode rn molecular biology.