BACILLUS MALLEI 369 



local swelling which quickly subsides. In horses infected with B. 

 mallei a swelling appears within a few hours which is painful and 

 inflamed ; it gradually enlarges for twenty-four hours or more, and the 

 lymphatics of the area usually become prominent. The swelling may 

 persist for several days, but gradually diminishes and usually disap- 

 pears within ten days. The temperature rises with the local swelling 

 and reaches a point 1 to 2 or even 3 above the normal within twenty- 

 four hours. The animal usually exhibits all the signs of a generalized 

 reaction; it becomes listless, the coat roughens, and there is greater 

 or lesser generalized weakness. The temperature usually persists for 

 forty-eight hours or more. The reaction is specific but requires 

 experience for its interpretation. Variations in temperature are 

 caused by strangles, .bronchitis and other inflammatory infections, 

 hence the temperature should be observed for some hours before the 

 injection of the mallein. A positive reaction is of more diagnostic 

 value than a negative reaction. It should be borne in mind that 

 mallein interferes with serologic tests, hence the latter should be made 

 before the injection of mallein*. 



Pathogenesis. Animal. Cattle appear to be immune to glanders; 

 swine are but slightly susceptible; cats, sheep, goats, field mice and 

 guinea-pigs' are susceptible, but white mice are refractory. 



Acute glanders in horses and asses begins after an incubation period 

 of from three to six days with an abrupt rise of temperature and a 

 viscid, purulent nasal discharge. The nasal mucosa, at first deeply 

 congested, becomes ulcerated; the regional lymph glands enlarge 

 and may suppurate. The lungs become involved and death usually 

 occurs within six to fourteen days; occasionally the animal lives 

 several weeks. The onset of the chronic form is somewhat more insid- 

 ious, and the symptoms are less violent. There is usually a nasal 

 discharge which may be blood-streaked, and the superficial glands 

 of the neck are palpable. The cutaneous lymph glands and usually 

 the lymph channels as well become generally enlarged, and they may 

 break down and suppurate. The disease may run a very mild course, 

 hardly noticeable, and frequently terminates in a cure after months 

 or years. 



The injection of material from ulcers, nasal secretion, or lymph 

 glands into male guinea-pigs leads, usually within two or three days, 

 to a characteristic lesion, unless the material is grossly contaminated 

 with other organisms, namely, a purulent orchitis; the testicle 

 enlarges until it can not be retracted, and the inflammation spreads 



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