BACILLUS EQUISEPTICUS 229 



infectieuse (French), is a disease of horses claimed by a number of 

 observers to bs due to the Bacillus (bipolaris) equisepticus. 



Occurrence. The disease occurs sporadically, and also as wide- 

 spread epidemics. It has been observed in Europe, America, and 

 South Africa. It became prevalent in the eastern part of the United 

 States in 1872-3, and from there has spread over the entire country. 



Pathologic Lesions. In the catarrhal form the mucous membranes 

 of the respiratory and gastro-intestinal tract show an intense con- 

 gestion often accompanied by edematous infiltrations, particularly 

 in the submucous connective tissue of the larynx, the pylorus, and the 

 small intestines. The subcutaneous connective tissues are likewise 

 often infiltrated with a watery exudate. Peyer's patches of the small 

 intestine and the mesenteric glands are swollen, and are reddish gray 

 on section. The pleural and peritoneal cavities frequently contain a 

 reddish, cloudy, serous fluid. The spleen shows some swelling, and 

 the lungs are edematous. In the pectoral form the lungs contain lobar 

 or lobular areas of consolidation, and the pleura is in a condition of 

 serofibrinous inflammation. The consolidated areas in the lungs 

 become necrotic, and contain a soft, dirty grayish-brown or greenish, 

 very fetid mass. The necrotic foci sometimes break through the 

 pleura and establish a pneumothorax or pyopneumothorax. In the 

 catarrhal form the conjunctive of the eyes are intensely reddened 1 

 (brick red or mahogany red), and the submucous connective tissue 

 is edematous. The eyelids swell, covering the eyeball to a large 

 extent. If the lids are opened forcibly there is an abundant flow of 

 tears, and later a mucopurulent discharge. 



Morphology. The Bacillus equisepticus is described by Nocard 

 and Leclainche, according to Ligniere's findings, as follows: It is a 

 slender, short bacillus with rounded ends and of about the same size 

 and staining properties as the bacillus of fowl cholera. In cultures it 

 shows as a very small diplococcus (coccobacillus). It is immobile, 

 strictly aerobic, and Gram negative. It is present in the blood in 

 small numbers only, and difficult to find. 



Cultural Properties. Artificial cultures are difficult to obtain. They 

 require the intraperitoneal injection of 4 or 5 c.c. of the horse's 

 blood, pleuritic fluid or juice from the lungs into a guinea-pig, in 

 which they produce a peritonitis, the exudate from which contains 

 numerous ovoid bacteria, from which culture media are inoculated. 

 Bouillon cultures, after twenty-four hours, are uniformly clouded, and 

 the reaction of the medium remains the same even after several days. 

 On gelatin at 20 C. very small, round, almost transparent colonies 

 are formed after two or three days. The bacillus does not grow well 

 on plain or glycerin agar; it grows in milk without coagulating it; 

 no growth occurs on potatoes. The best culture medium is bouillon 

 to which a small amount of sterile horse's blood serum has been added. 



1 The name pink-eye is derived from this symptom. 



