618 CHRONIC INFECTIOUS DISEASES 



similarly affected. The intestinal lesions are very common, 

 and consist of a large number of small nodules found on the 

 mucosa. By confluence large areas appear as do ulcers. On 

 the serous coat of the intestines are found nodules varying 

 in size from a millet seed to a hazel nut. The mesentery may 

 show similar lesions. The abdominal lymph glands are 

 usually enlarged and caseated. In some cases on opening 

 the abdominal cavity a striking picture is presented as the 

 entire visceral peritoneum is covered by hundreds of very 

 small white or grayish nodules. The lesions in the lungs are 

 similar, although not usually so marked as in the liver and 

 intestines. The affected joints are enlarged, contain a cheesy, 

 yellowish mass and the articular cartilages are eroded. The 

 other organs and tissues are not often involved, although 

 nodules are found occasionally in the kidneys, ovaries, tes- 

 ticles, pericardium, heart and gizzard. In parrots the disease 

 is usually localized around the head and in the mouth. 

 Nodules varying in size and condition are found containing 

 the same cheesy, yellowish material. 



Symptoms.— In the early stages of avian tuberculosis the 

 symptoms are very indefinite. The disease is chronic and 

 characterized by a gradual emaciation without any specific 

 clinical symptoms. The emaciation continues in spite of good 

 appetite. The appetite persists as a rule until the beginning 

 of a general toxemia, when it diminishes to disappear entirely 

 during the latter stages of the disease. Symptoms of anemia 

 develop as evidenced by paleness of the mucous membranes, 

 comb and wattles, dulness, and rough plumage. During the 

 latter stage the fowls are listless, much emaciated, and show 

 all the symptoms of asthenia. Diarrhea sets in, and complete 

 exhaustion is followed in a few days by death. There is con- 

 siderable variation in the period of time required for the 

 development of the general symptoms. When the bones and 

 joints are affected, there is usually an involvement of the 

 joints of the wings, and the tarsal joints. At first the joint 

 shows swelling which develops gradually. The swelling is 

 firm at first, but in nearly all cases becomes soft and fluctuat- 

 ing, and when opened discharges a yellow, caseous material. 

 The bird is lame and the wings are held pendent. 



