A coligranuloma was diagnosed in two birds during routine necropsy examination. Necropsy examination revealed hard nodular growth on serosal surface of intestine, mesentery, oviduct and uterus. Histologically, section of nodular growth showed granuloma with heterophilic and lymphocytes infiltration. Necrotic area was surrounded by a collar of giant cells, macrophages and lymphocytes with a layer of fibroblast at periphery. Isolation of organism on MacConkeys agar revealed Escherichia coli.
Coligranuloma (Hjärre’s disease) was first described by Hjärre and Wramby (1945) characterized by typical granuloma on the serosal surface of the intestine and in the liver but not in the spleen (Barnes et al., 2008). Coligranuloma is caused by Escherichia coli and is relatively a rare disease of the domestic chicken. It has been considered as a disease of older birds associated with lingering mortality. However, mortality up to 75 % has been reported (Barnes et al, 2008). Present paper describes pathomorphological changes in cases of coligranuloma in layer birds of varied ages.
Materials and Methods
During routine necropsy, one bird each out of three and four bird necropsied showed characteristics gross lesions of coligranuloma. The detail necropsy was carried out and gross lesions were recorded. Affected part of intestine and mesentery was collected in 10 per cent formalin for histopathological examination. Tissue sample was processed, embedded in paraffin and sections of 5 µm thickness were taken and stained by Haematoxylin and Eosin (H & E) (Kim et al., 2013). The affected tissue and liver samples were collected for microbial isolation from birds of 55 week age flock. History taken from farm manager revealed the birds were kept in cages in one flock and on litter in other flock. The age of the birds kept on litter and in cages was 34 week and 55 week, respectively.
Results and Discussion
Grossly, the carcass of both birds appeared dehydrated and emaciated. Upon opening carcass, serosal surface of intestine, uterus, oviduct and mesentery showed small, circular, focal but multiple greyish-white raised nodules (Fig. 1 and 2).
|Fig. 1: Intestine showing multiple grayish white nodules on serosal surface||Fig. 2: Multiple grayish white nodules on serosal surface of intestine and mesentery|
The sizes of the nodules were in the range of 1-4 mm in diameter. On cut section, nodules were hard to cut and grayish white in colour. Adhesion of intestine with mesentery was also seen in bird of 55 week age. The gross lesions observed in the present investigation are in accordance with reports of various authors (Islam et al., 2007; Barnes et al., 2008; Rahimi and Siavash Haghighi, 2014).
The microscopic examination of the affected tissue showed granuloma attached to serosal surface of intestine (Fig.3). Higher magnification of section of nodule showed classical granuloma and showed sheet of heterophils or sparse heterophils and large population of lymphocytes infiltration in the center (Fig.4 and 5). The necrotic area was surrounded by a collar of giant cells, lymphocytes, macrophages and a layer of fibroblast at periphery (Fig. 6). The histological lesion observed in coligranuloma corroborate with the findings of the authors reported earlier (Islam et al., 2007; Barnes et al., 2008; Rahimi and Siavash Haghighi, 2014), except that the predominant cells were lymphocytes than the heterophils. The microscopic lesions need to be differentiated from avian tuberculosis. The microbial isolation showed minute pink colonies on MacConkeys agar which upon Gram’s staining showed gram negative short rods.
|Fig 3: Lesion depicting nodule attached to serosal surface of intestine (HE x 20 X)||Fig 4: Section of nodule showing classical granuloma (HE x100X )|
|Fig 5: Section of nodule showing large population of chronic inflammatory cells, particularly lymphocytes (HE x600X)||Fig 6: Section of nodule showing foreign body giant cells along with lymphocytes and macrophages (HE x600X)|
The colonies of Eosin Methylene Blue (EMB) agar showed metallic green sheen which is characteristic feature of E. coli. Moreover, acid fast staining of the smear from nodules did not show acid fast organism and thus, avian tuberculosis was ruled out. In the present case, coligranuloma was diagnosed in birds of 34 week and 55 week age. Coligranuloma is considered as a disease of old birds, however there is increased incidences of occurring disease at early age with increased mortality. Rahimi and Siavash Haghighi (2014) recorded coligranuloma at the age of 9 week with total mortality of 20% over a two week period.
In conclusion, the present paper put on record the occurrence of coligranuloma in 34 week and 55 week age layer birds. Detail gross and microscopic pathology of coligranuloma are discussed.