Cow Pox. 219 



In the affected herds a great number of the animals may become infected 

 within a short time. Thus Bartos observed among 210 cows 90 infected inside 

 of two weeks. In this instance the children of the owner had been vaccinated 6 

 days previous to the first case. The disease was observed in an epizootic outbreak 

 by Freger in the Arrondissement de Bayeux, where the milkers disseminated the 

 disease from stable to stable. 



According to Leese pox occurs in Pendschab among camels with such fre- 

 quency that most of the animals become affected in the first or second year of 

 their lives. As a result of this, older camels rarely become affected, but if so, 

 usually with generalized pox and pyemic manifestations. 



Etiology. According to the investigations of Negri (1905), 

 which have since been confirmed by Eemlinger & Osman Nouri, 

 Carini, NicoUe & Adil-Bey and others, the cow pox virus passes 

 through not too dense porcelain filters, therefore it apparently 

 belongs to the ultra-visible micro-organisms. 



Negri filtered vaccine fluid collected- from young cows through 

 Berkefeld filter under 3 atmospheric pressures, and produced with the 

 filtrate, the characteristic vaccinia keratitis in rabbits, and true pox 

 postules on the udders of cows. The fact that filtrate from lymph which 

 has stood for some time is frequently more infective than similar sub- 

 stance from fresh material, is explained by Carini thus that the virus 

 is contained in cells, and is freed only after long maceration. (According 

 to Nicolle & Adil-Bey this may be hastened by pancreatic digestion). 

 Up to the present time only abortive pox could be produced with filtrates. 



Proscher is said to have succeeded in cultivating the ultra-visible pox virus 

 on artificial media. On solid media prepared especially for this purpose, smeary 

 deposits develop by changes of the nutritive substrata, which do not contain 

 microscopically visible micro-organisms, but which yet produce pox postules in calves 

 up to the third or fourth passage. 



Pathogienicity. Inoculation of cow pox lymph into the skin 

 of cattle results in a typical pox eruption, which is always con- 

 fined to the point of inoculation, or to the parts immediately 

 surrounding it. The eruption is associated with very slight 

 general disturbances. Young cattle are especially susceptible 

 to infection, which is favored by a previous injury of the epi- 

 thelium of the skin (shaving, etc.). Man, buffaloes, camels and 

 horses are. susceptible to a similar extent ; hogs, sheep and dogs, 

 to a lesser degree, and in these animals cutaneous inocula- 

 tion results only in a local exanthema. The rabbit is very 

 susceptible, and according to Calmette & Guerin, the guinea pig 

 likewise. 



Subcutaneous inoculation of the virus produces in cattle 

 an edematous infiltration, in horses in addition to this an erup- 

 tion of pox, while an intravenous infection causes only fever 

 without exanthema in these animals. Chauveau and Arloing 

 observed the development of a vesicular exanthema in young 

 horses following an intravenous infection. 



The injection of lymph into the milk ducts of cows results 

 in 2 to 3 days in moderate fever, swelling and sensitiveness of 

 the udder, whereupon on the ninth day the secretion of the 

 udder becomes purulent and soon bloody. The secretion retains 



