Why do we record disease?

Historical aspects Control and prevention of animal diseases require insight in disease occurrence in all its respects. Different ways of recording occurrence of diseases and, when possible and relevant, also of the infectious agents have therefore always been a natural part of the traditional veterinary profession. This was well exemplified by Calvin W Schwabe in his book Veterinary Medicine and Human Health (Schwabe 1964). In his introduction, Schwabe also underlines the wide area and complex status of this field by the following quote from Rudolf Virchow: "Between animal and human medicine there is no dividing linenor should there be. The object is different but the experience obtained constitutes the basis of all medicine". Increased demands for a basis as correct as possible for decisions on the allocation of rescources for disease control can perhaps be seen as the main reason for the considerable improvement of methods for recordings that have taken place during the last 30-year period. In the 1970s the term epidemiology was introduced, as reflected in different text books in this field (Schwabe et al. 1977, Thrusfield 1986 and 1995, Martin et al. 1987 and Noordhuizen et al. 1997). The epidemiology emphasized a holistic approach to disease and epidemiology was not merely the study of epidemics. For the need to look into the future, and also the economic consequences of disease intervention, the focus was on costbenefit calculations and mathematical models to mimic disease outbreaks, as also are presented in the textbooks above. The current focus on risk assessment can be seen as a further step whereby the risks associated with different hazards can be compared (Mac Diarmid,1993).