INFECTIOUS DISEASES. 511 



great loss among tho \v:n horses of Rome and the siiiTonntling dis- 

 trii't. Later, in KIIS, an epizootic of tliis disease visited (jlerniany 

 and spread to other parts of Europe. In 1711, under the name of 

 "epidemica e(|Uorum," it foUowed the tracks of tlie great armies 

 all over Europe, causing immense losses among the horses, while 

 rinderpest was scourging the cattle of the same regions. The two 

 diseases were confounded with each other, and were, by the scien- 

 tists of the day. sui)posed to he allied to the typhus, which was a 

 plague to the human race at the same time. We find the first advent 

 of this disease to the British Islands in an epizootic among the 

 horses of London and tlie southern counties of Englaiul in 1732, 

 which is described by Gibson. In 1758 Robert Whytt recounts the 

 devastation of the horses of the north of Scotland from the same 

 trouble. Throughout the eighteenth century a number of epizo- 

 otics occurreil in Hanover and othei" portions of (Jermany and in 

 France, which were renewed early in the present century, with 

 comjilications of the intestinal tract, which obtained for it its name 

 of gastroenteritis. In 17()G it first attacked the horses in North 

 America, but is not described as again occurring in a severe form 

 until 187()-1S7*J, when it spread over the entire country, from Canada 

 south to Ohio, and then eastward to the Atlantic and westward to 

 California. It is now a permanent disease in our large cities, select- 

 ing for the contiiHumce of its virulence young or especially sus- 

 ceptible horses which pass through the large and ill-ventilated and 

 uncleaned stables of dealers, and assumes from time to time an en- 

 z(M)tic form, when from some reason its virulence increases. It as- 

 sumes this form also when, from reasons of rural economy and com- 

 merce, large numbers of young and more susceptible animals are ex- 

 posed to its contagion. 



Etiolor/y. — The experiments of Dieckerhofi' many years ago provcil 

 that the disease may be transmitted to healthy animals by intravenous 

 injection of warm blood from affected hoises. 



Further investigations revealed the fact that blood from atfeited 

 horses, even when passed through porcelain filters, may transmit 

 the disease, thereby proving that the causative agent l)elongs to the 

 so-called filterable viiuses. This has been further substantiated by 

 (Jaffky, who showed in his recent experiments that the disease may be 

 transmitted with defibrinati-d as well as with filtered blood, in which 

 cases the typical form of influenza developed in in<Hulated aninuils 

 in from five to six days. These findings were also .substantiated by 

 Basset. Fuither observations have also proved that apparently re- 

 covered animals may harbor the infection for a long time and still be 

 capable of transmitting the disease. Such viiiis carriei"s are no doubt 

 responsible for numerous outbreaks of this disease when, in a locality 



