304 Sheep Pox. 



as for instance in sheep stables, it may retain its virulence for six months, and 

 even out of doors it may remain infectious for a long period of time. In 

 Siebenbiirgen it was noted in one case that lambs became affected with pox in 

 great numbers, in a stubble pasture in which 62 days previously • sheep affected 

 with pox had been pastured on young wheat (Dely). 



Pathogenicity. A cutaneous inoculation of a small drop 

 of pox lymph usually produces in susceptible sheep only a local 

 pox eruption. In some cases, however, especially in lambs and 

 by using very virulent lymph, a generalized pox eruption re- 

 sults. In the latter case, .after an incubation period of 2-2l^ 

 days, a dark red nodule develops at the point of inoculation, 

 which from the fourth to fifth day on changes into a vesicle. 

 When the nodule begins to soften the body temperature rises 

 to 39.5-40.6° C, later to 41.5-42.6°, indicating the entrance of the 

 virus into the blood circulation. This is followed by the forma- 

 tion of nodules, which change into pox vesicles on the mucous 

 membrane of the lips, on the nostrils, the eyelids, later also in the 

 axillary region, on the thighs, around the vulva and rectum. At 

 the same time the general febrile symptoms reach a high degree 

 until at the beginning of the third week, or somewhat later, death 

 ensues with manifestations of septicemia. After subcutaneous 

 infection the temperature rises with the beginning of the local in- 

 flammation ; this is shown by a firm swelling which may reach 

 the size of a fist, containing numerous nodules, later forming 

 confluating pox vesicles on its surface, while the general pox 

 eruption develops in from 5-6 days after the infection in the 

 same manner as though resulting from a cutaneous inoculation. 

 Intra-peritoneal injections of lymph are followed by the forma- 

 tion of nodules on the peritoneum, with bloating, and sensitive- 

 ness of the abdomen, while injections into the trachea lead to 

 a specific inflammation of the mucous membrane' of the air 

 passages, with marked difficulty in respiration as an immediate 

 result, whereupon, in from 6-8 days a, generalized pox eruption 

 develops '(Bosc). Injections of lymph into the circulation may 

 produce only febrile manifestations without eruptions, but sheep 

 are immunized after such a short affection to the same extent 

 as after recovery from a typical infection (Semmer & Raupach). 

 An intra-cerebral inoculation results in 6-8 days in fever, the 

 animals dying within one week afterwards, while injections of 

 lymph into the milk cistern produces a pox eruption oh the 

 mucous membrane of the milk ducts, the milk in such cases 

 containing the infective agent for two weeks (Nocard). 



Outside of the contents of the vesicles the virus is not 

 present in the pure secretions or in the blood, or in the latter 

 only exceptionally immediately before or at the beginning of 

 the pox eruption (Bosc; Nocard & Roux failed to obtain any 

 positive results from the inoculation of blood). 



Natural Infection. The virus of sheep pox probably enters 

 the lungs with the inhaled air, and from there passes through 

 the alveoli directly into the blood, which disseminates the virus 



