Distinguishing between natural and unnatural outbreaks of animal diseases.

An intentional outbreak of disease among livestock, or agricultural crops, will share a number of characteristics with those aimed at humans - unexpected pattern of disease in season or place, possible explosive incidence, unusual pathogen either in itself or of its genetic structure, difficult diagnosis - but there will also be notable differences: human cases, if they occur, will be coincidental and the major impacts will be delayed and of severe economic consequence. An investigative and analytical protocol is proposed for identifying such an event. Unless the nature of the event is self-declaring, such investigations necessitate a very thorough and careful investigation by a dedicated and experienced epidemiologic team. Atthe same time a country should take steps in advance of such an event to be prepared and to save time later, such as determining possible targets, identifying early warning indicators, establishing molecular biologic expertise and reference collections of possible pathogens, and preparing a tactical and forensic response.