Investigation of Disease Outbreaks and Chronic or Inapparent Disease
Disease in populations occurs across a spectrum from sudden explosive outbreaks in which there is obvious morbidity or mortality, to very chronic and protracted conditions in which it may be difficult to detect sick animals or any other evidence of the disease. Disease in wild animals is often likened to an iceberg with the great bulk of the problem hidden from view. In this analogy, the exposed tip is often the disease outbreak, while chronic disease is that portion hidden most deeply underwater. Each of these extremes presents some peculiar difficulties for the disease investigator. Outbreaks are usually shortlived, transitory phenomena that demand immediate attention and that often excite public and media attention. This may result in considerable pressure to find an answer as to the cause. There may also be an expectation that control measures should be instituted which, in many cases, may not be practical or justified. In contrast, the problem with insidious diseases is often one of identifying affected animals and of assessing the effect of the disease. Chronic diseases may have important effects on populations but, because of their covert nature, it may be difficult to convince administrators, or the public, of their occurrence and of the need for their investigation or management. This chapter will deal with techniques particularly suited for the investigation of these dissimilar types of disease.
KeywordsWild Animal Disease Outbreak Affected Animal Dead Bird Malignant Catarrhal Fever
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