Emergency Disease of Livestock 1-2. [antikvár]

1X1 INTRODUCTION The major epizootic diseases may devastate livestock production in a country. Now, more than ever, these diseases have the potential for rapid and unexpected spread. This is because of the ever-increasing international movement of people, livestock and livestock products. There have been many examples of the ability of diseases to spread rapidly from country to country in recent history. Thirty years ago African swine fever may have been regarded by many countries as a remote and obscure disease. However, it has since spread to Europe, South America and the Caribbean and is now regarded as one of the most important emergency diseases of pigs. Newcastle disease came to international veterinary attention only in 1926 but has since caused several panzootics and has devastated poultry industries in many countries. Arthropod-borne diseases have demonstrated their ability to spread very rapidly as witnessed by epizootics of African horse sickness and Rift Valley fever since 1950. Rinderpest, one of the greatest cattle scourges ever known, is again spreading internationally. Quarantine action is of course the first barrier against the introduction of these diseases. However, countries must be prepared to mount an adequate and fast response should one of the emergency diseases penetrate their quarantine barrier. This means having a farming community and particularly a field veterinary service alert to the possibility of an exotic disease. Furthermore, it is crucial that the veterinary services of countries carry out advance contingency planning so that an effective disease control campaign can be carried out in an emergency. A key to mounting an effective response is early and accurate diagnosis of the disease. If the disease can be diagnosed before it has established a foothold the battle to control it is more than half won. Alternatively if it is not diagnosed until it has established a reservoir in livestock, feral animals or wildlife it may be impossible to eradicate. This, the first volume in a two volume series on Emergency Diseases of Livestock, is aimed to assist veterinary administrators and field staff in the recognisition and diagnosis of the more important emergency diseases of animals. It describes the salient features of each disease and describes how to secure a diagnosis. Whilst it briefly describes the laboratory tests that are employed, it is not meant to be a laboratory diagnostic manual. The tests are only described in sufficient detail to give field officers an appreciation of how to collect the best specimens and what they should expect of the laboratory. The second volume will deal with the equally important subject of pre-planning for a disease emergency and management of a major disease control programme. I ! i - 3 - DKFIWITION AMD NATURB OF EMERGENCY DISEASES The presence of a potentially disastrous animal disease in a country or region, or even the suspicion of such a disease, constitutes a disease emergency. This applies to any animal diseases which present a sudden and major threat to: a. livestock production in respect of food, fibre or animal traction power; b. public health; or c. export of livestock or livestock products, and for which the country's existing resources may not be adequate. Usually, infectious diseases are the cause of an animal health emergency. This may result from the introduction of a hitherto exotic disease (or a new strain of its aetiological agent) to a country or region. An emergency may also occur in an enzootic country through a sudden change in the characteristics of enzootic organisms. For example, new strains of exalted virulence may emerge or there may be an antigenic shift such that existing herd immunity and available vaccines no longer provide adequate protection. Major emergency diseases, and other diseases which may cause disease emergencies in some situations, have already been described in Volume 1. Animal health emergencies may sometimes arise in other ways. Accidental contamination of animal feedstuffs, pastures or water supplies by toxic chemicals, pesticides or radioactive materials for example may cause a sudden, unexpected animal disease or public health threat in a localized area or even a whole province or region of a country. Although the response to such an emergency will differ considerably in detail to that for an infectious disease, the general principles of contingency planning, epidemiological investigation and management of an emergency campaign are equally applicable. Natural disasters such as floods and fires may also cause an animal health emergency. This should be taken into account in a country's general disaster planning for such events.