The Emergence of Zoonotic Diseases Understanding the Impact on Animal and Human Health: Workshop Summary (2002) / Chapter Skim
Currently Skimming:
2 The Importance of Zoonotic Diseases
2 The Importance of Zoonotic Diseases
Pages 10-25
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 10... ...
This series of events is not specific for zoonotic infections, except possibly that zoonotic agents are rarely sexually transmitted. The zoonoses, however, illustrate some of the more interesting and complex patterns that have evolved in nature.
|
From page 11... ...
As with bacterial virulence factors, the elements responsible for viral virulence affect both zoonotic and nonzoonotic agents equally. Examples of Pathogenesis and Virulence in Zoonoses Zoonotic diseases offer some interesting insights into pathogenesis and virulence, as well as to the links between them.
|
From page 12... ...
The bacillus does not usually penetrate intact skin. Percutaneous infection occurs through open lesions or insect bites.
|
From page 13... ...
Edema factor is a protein that is activated by calmodulin from the host and then produces a substance called cyclic adenosine monophosphate that stimulates edema. Protective antigen is a protein that is broken apart by cellular protease and then is capable of transporting lethal factor and edema factor to host cells.
|
From page 14... ...
Need for Additional Research Anthrax and Rift Valley fever illustrate diseases for which there are good studies of the pathogenesis and virulence of the agents in humans or at least in animal models. Such studies may be long in coming for some of the newly emerged zoonoses, such as West Nile encephalitis and Nipah encephalitis.
|
From page 15... ...
The United States discontinued research on offensive biological weapons in 1970, and a multilateral agreement to halt offensive biological warfare programs, the Biological and Toxin Weapons Convention, was ratified in 1975. However, ratification of this agreement did not end the threat of biological weapons attacks.
|
From page 16... ...
In general, however, zoonotic agents that might prove useful in terrorist attacks must be produced as respirable aerosols, since nearly all of them are not highly contagious. Furthermore, unlike many chemical warfare agents, biological agents are neither volatile nor can they penetrate intact skin.
|
From page 17... ...
These purposes include, for example, implantation of fetal pig neuronal cells into the central nervous system of people suffering from Parkinson's disease, passing blooci from people with liver failure through a crevice that contains pig liver cells, and infusing pig insulin-proclucing pancreatic islet cells into people with diabetes. For the purpose of Public Health Service policy discussions, xenotransplantation now refers to any proceclure that involves the transplantation, implantation, or infusion into a human recipient of either (1)
|
From page 18... ...
Pretransplant screening is nested in animal husbandry techniques that limit and define the exposure history of the source animals. The risk that human recipients will be infected with exogenous viruses and other identifiable infectious agents can be reduced to negligible levels by limiting the ceocra~ohic origin and lifelong contacts of Potential source animals.
|
From page 19... ...
These observations support concerns that PERV expressed from porcine xenotransplantation products may be able to infect human recipients. Since October 1997, when evidence that PERV could infect human cells in vitro emerged, the Food and Drug Administration has required all sponsors of porcine xenotransplantation product trials to demonstrate plans for posttransplantation surveillance for PERV infections in recipients using testing methods adequate to detect such infections.
|
From page 20... ...
However, from simply a practical standpoint, it is clear that we currently lack appropriate animal husbandry techniques, such as those in place for raising the pigs used in clinical trials, for maintaining a population of nonhuman primates. Taken together, these factors have led the Food and Drug Administration to ban xenotransplantation trials using nonhuman primates until adequate demonstration of safety and adequate public discussion of ethical issues have occurred.
|
From page 21... ...
Food animal veterinarians over the past 30 or 40 years have adapted to revolutionary changes, driven by economics and technology, in the structure of animal agriculture. These changes include increasingly larger herd sizes, intensive production management systems, improvement of but simultaneous narrowing of the animal gene pool, vertical integration, and innovations of housing and physical facilities.
|
From page 22... ...
Furthermore, trade in agricultural products results in better global nutrition, providing a wide variety of fruits and vegetables in developed countries and more plentiful and affordable meat in developing countries. Adequate nutrition affects host resistance on a population basis by providing an important preventive measure against the emergence of zoonotic diseases.
|
From page 23... ...
While the new process promised monetary savings, the notion that it might give rise to an emerging zoonotic disease was not even on the horizon as a contingency though it should have been. The costs for BSE eradication, which escalated dramatically after the European ban on importing British beef, have finally crested.
|
From page 24... ...
Whatever the etiology, the introduction of a major zoonotic disease has the potential for resulting in significant alterations in the structure of world trade. A particularly dramatic and threatening zoonotic disease linked to a trading incident could potentially shift globalization trends to a much more protectionist stance.
|
From page 25... ...
It is for this reason that risk assessment for the occurrence of zoonotic and other animal diseases has moved front and center in the international system of trade regulation.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.