CHAPTER XIII 
INFECTIOUS DISEASES FOR WHICH THE SPECIFIC 
CAUSE IS NOT DETERMINED 
General consideration. The study of microbiology has revealed 
the specific cause of a large number of the infectious diseases but there 
still remain several well recognized maladies for which specific micro- 
organisms have not been demonstrated. The methods that have 
been effective in finding the cause of other specific diseases have 
failed here. Their study, however, has revealed much concerning the 
nature of the virus and its location in the body of the infected animal, 
so that measures for their prevention have been formulated which are 
quite as efficient as they are for the diseases of known etiology. The 
viruses of this group of diseases are spoken of as ultramicroscopic. 
As many of them will pass through filters that hold back known bac- 
teria they are often called ‘‘filterable viruses.” 
RINDERPEST 
Synonyms: Contagious typhus; steppe murrain; cattle plague. 
Characterization. Rinderpest is the most fatal disease affecting 
cattle. It is a specific eruptive fever, occurring both sporadically and 
in epizoétics. It is characterized by a more or less typhoid condition, 
with lesions largely located in the mucosa of the digestive tract and 
skin, and by the infectious nature of all the tissues, secreta and excreta. 
It is a disease peculiar to cattle, although other ruminants are suscep- 
tible to it. 
History. Rinderpest seems to have been brought to western 
Europe by the importation of cattle from central Asia. It is supposed 
that it had long existed on the steppes of central Asia and eastern 
Europe. The first great epizodtic, of which there seem to be records, 
occurred about 1709 and spread over nearly all of the countries of 
Europe. It is reported that 1,500,000 cattle died from its effects 
during the years from 1711 to 1714. Ramazzini seems to have been 
the first (1711) to give a description of the symptoms and lesions. 
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