Some general problems of the zoonoses are conveniently treated here, although the infective agents belong to many species, causing many of the diseases of ICD 060–088, perhaps more than a hundred in all. Many of the zoonoses are vector-borne, an aspect that has already been treated in §5.5. It is probable that some infections, now considered as peculiar to man, have originated as infections of animals. Once the cycle of infection has been established in man, it may happen that an animal reservoir is no longer needed to perpetuate the infection; further, if such changes in the organism have occurred that it no longer causes natural infections in animals, it is classed as an epidemic or human disease rather than a zoonosis. Such a disease is measles, which possibly is a mutation from the distemper group of animal virus infections; cases can be made even for influenza and classical typhus as zoonoses.
KeywordsHuman Case Case Fatality Rate Francisella Tularensis Brucella Melitensis Wild Rodent
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