This is classic avian tuberculosis (usually caused by Mycobacterium avium subsp. avium), which can affect all types of birds.
It is a chronic, granulomatous bacterial infection that is slow to spread and is characterized by gradual weight loss. M. avium is prevalent worldwide and is spread by infective feces.
It is ZOONOTIC in immune-compromised people.
Dx: difficult. Positive wattle or skin tuberculin test confirms exposure but negative does not rule out disease. Suspicion can be based on seeing lots of acid-fast bacteria on smears from lesions.
Rx: none. Prevent by careful purchasing and/or quarantine (at least 6 months!) of new birds.
Improved sanitation and rapid flock turnover in commercial flocks has mostly eliminated this infection from these groups.
Candidiasis is an intestinal mycotic disease typically characterized by thickened mucosa and white, raised pseudomembranes lesions in the crop and esophagus.
Colibacillosis (Escherichia coli) is common in chickens and can cause subacute pericarditis, airsacculitis, salpingitis, peritonitis, and acute fatal septicemia. It can occasionally cause granulomas in the liver and spleen (but not the intestine, bone marrow like in this chicken). Lameness would also be less common in the history for colibacillosis.
Infectous coryza is a respiratory disease of chickens that acutely causes nasal discharge, sneezing, and facial swelling.
Ulcerative enteritis (Clostridium colinum) causes depression, anorexia, and diarrhea.
Image courtesy of VojtÄch Dostál.
