Diagnosis of Avian Tuberculosis in laying hens by pathological, microbiological and polymerase chain reaction (PCR): Case report

Avian tuberculosis was described at 50 week-old Lohmann chickens in a commercial chicken farm. The study materials were 50 week-old 20 pieces of chicken from 2 coops and 16 week-old 20 pieces of pullets from 4 coops in a commercial chicken farm. After necropsy, samples were processed routinely for histopathological and microbiological examinations. Macroscopically, hard consistency, numerous and different sizes, whitish-yellow caseificated-calcifiated nodules were seen on the liver, spleen, kidneys and intestinal serosa. At microscopic examination, various sized granulomas, which have been caseification necrosis surrounded by epithelioid histiocytes and multinucleated giant cells, were found at liver, spleen, wall and serosa of intestine. Numerous acid-fast bacteria were seen on histopathology at necrosis and macrophages in the liver, spleen and intestines by Ziehl – Neelsen staining. Mycobacterium avium spp was produced at microbiological inoculations in liver, spleen, intestines and ovaries. Mycobacterium avium subsp. avium from these cultures was identified by PCR. It was thought that infection could be by fecal-oral route due to both intestinal tuberculosis in hens and common disease in coop. Therefore, the role of chicken manure may also be taken into account for the spreading of the disease.