252 



VETERINARY BACTERIOLOGY 



teristic if potatoes having too acid a reaction are used. They may 

 be neutralized previously to inoculation by soaking in dilute sodium 

 carbonate. 



Physiology. B. mallei is aerobic and facultative anaerobic. 

 Its optimum growth temperature is 37, but its growth limits, at 

 least in freshly isolated cultures, are about 25 and 42. Its 

 thermal death-point is 55, with five minutes' exposure. 



Pathogenesis. Experimental Evidence. There is an abun- 

 dance of evidence to prove that B. mallei is the cause of glanders. 

 All the lesions of the disease may be duplicated by the experi- 

 mental inoculation of pure cultures into laboratory animals and 



the horse. The guinea-pig 

 is very susceptible. A sub- 

 cutaneous inoculation is fol- 

 lowed within a few days by 

 local swelling and indura- 

 tion, which soon ulcerates 

 and discharges to the 

 surface. The disease 

 spreads largely through the 

 lymph-channels, and the 

 lymph-nodes enlarge and 

 suppurate. Various meta- 

 static infections of the 

 joints, the lungs, and other 

 organs occur. Death seems 

 to be due to exhaustion. 



Infection may similarly be transmitted to the rabbit. The horse 

 may be readily infected, as may sheep, goats, the cat, and the 

 dog. Cattle and the house-rat do not contract the disease. It 

 occurs in man through infection from glandered animals and 

 through working with pure cultures in the laboratory. 



Character of Disease and Lesions Produced. The disease as 

 found in equines may be either of an acute or a chronic type. 

 The former is commoner in the ass and mule, and the latter in 

 the horse. The acute type of disease is commonly ushered in with 

 a chill, there is a mucopurulent discharge, and death usually occurs 

 in from one to four weeks. The chronic type shows no marked 



Fig. 107. Bacillus mallei, in section 

 from the spleen of a field-mouse (Frankel 

 and Pfeiffer). 



