300 BACILLUS OF SWINE ERYSIPELAS 



Resistance. The bacillus of swine erysipelas is more resistant 

 than most pathogenic non-spore-forming bacteria. It can remain 

 alive for one month dried out and kept in the incubator at 37 C. ; in 

 the dried condition it resists sunlight for twelve days ; and sometimes, 

 in moist condition, a temperature of 70 C. for fifteen minutes. 

 According to Petri it has survived in infected pork after broiling it 

 for two and one-half hours; boiling of the meat in water, however, 

 promptly kills the bacillus, which can remain alive a long time in 

 salted or smoked meat and in buried cadavers. 1 



Natural Infection. Hogs are the only animals subject to natural 

 infection with the bacillus of swine erysipelas. They are especially 

 susceptible when they are from three to twelve months old; sucking 

 pigs are not very susceptible, nor are animals older than one year. 

 The latter have probably acquired immunity by a previous attack, 

 which may have been so mild as to have escaped attention. Natural 

 infection occurs through the skin or the intestines; infection through 

 the lungs by inhalation has never been proved. It is believed that 

 the disease is most commonly contracted through the intestines, 

 because large numbers of bacilli are found in them and also because 

 the affection often occurs extensively among animals kept in one 

 place under the same conditions. Food and water contaminated with 

 the feces of sick animals are a fruitful source of spreading the disease 

 to large numbers of animals. The importation of the disease into 

 previously uninfected territories takes place through sick animals or 

 their products. Both Cornevin and Kitt have demonstrated the in- 

 fective character of the feces of sick animals. Olt, Jensen, and 

 Baumeister have shown the presence of erysipelas bacilli in the 

 tonsils, intestines, and lymph glands of otherwise healthy hogs. 



Artificial Inoculation. Gray and white mice, pigeons, and rabbits 

 are very susceptible to artificial inoculation with fresh cultures of the 

 bacillus or with blood, juice from the organs, etc., of hogs sick with 

 the disease or dead from it. If a mouse is inoculated subcutaneously 

 with a small amount of infected material it becomes very sick after 

 twenty-four hours, and generally dies within four days under repeated 

 attacks of suffocation. This form of death is quite characteristic 

 in mice infected with the bacillus of swine erysipelas. Field mice are 

 not susceptible to the organism. Pigeons die on the third or fourth 

 day after inoculation, and they likewise, though not to so marked a 

 degree as mice, show respiratory difficulty before the fatal termination. 

 If rabbits are inoculated cutaneously or subcutaneously at the ear, 

 an erysipelas-like swelling and redness appears at the point of in- 

 jection. The local process may disappear, or it may spread and lead 

 to a general infection and death. Sometimes death does not occur 

 until after a prolonged cachectic condition. If rabbits are inoculated 



1 In cadavers it has been found alive after 280 days. 



