260 



Hog Cliolera. 



73 townships, in Italy 14,499, in Rouniania 1,829, in Russia 27,223, in Sevvia 45 

 eases, while in Denmark and in Holland the tlisease appeared less frequently, in 

 Sweden and Norway (in 1903 468 cases, of which 450 occurred in Dep. Akershus) 

 only sporadically. 



In the T'nited States the disease (hog cholera and swine plague) caused 

 in the year of 1S73 losses amounting to 20 million, in 1882 13 million, in 1884 

 and 1885 25 and 30 million dollars respectively, while in 1888 the loss was estimated 

 to have affected 45,000,000 hogs of a value of 200 million dollars, and in 1903 

 Salmon estimated the loss at 50 million dollars. 



Etiology. According to the results of investigations by 

 Dorset and his co-workers which, as already mentioned, have 

 since been snbstantiated by other investigators, hog cholera is 

 caused l)y an iiltra-microscopic virus, which passes the ordinary 

 porcelain filter. Attempts at cultivation, or even increasing the 

 amount of virus have up to the present been fruitless. 



Pathogenicity. Subcutaneous injections of 1-2 cc. of filtered, 

 defibrinated blood, blood serum or organ juices, produce in 

 young hogs, after an average incubation period of 8 to 10 days, 

 sometimes however in four days or only after 20 days, and 

 witliout any local reaction, an acute febrile affection with inflam- 



Fig. 45. Flog Cliolera. Artificial infection with filtered material from a hog affected 



with cholera. The first rise up to the fourth day of sickness is caused by the primary 



infection, tlie second by the secondary infection. 



matory swelling of the conjunctivae, eczematous eruption of the 

 skin, followed by diarrhea (Fig. 45; the quantity of blood does 

 not affect the outcome of the disease). In some of the cases 

 the animals die in 3 to 4 days with an acute affection, whereupon 

 the autopsy reveals exclusively hyperemia and acute swelling 

 of the internal organs, as well as hemorrhages on the serous and 

 mucous membranes (sometimes also a great quantity of serous 

 transudate in the pericardium). If the animals remain alive 

 for a longer time ulcerative and necrotic processes may be found 

 in the intestines, in other cases again pneumonic changes 

 will be observed which are similar to those found in the acute 

 pure swine plague. If the animals remain alive still longer the 

 affection of the intestines and the lungs develops in a more 

 chronic form, whereupon the animals die greatly emaciated, 



