Patho-morphological Based Diagnosis of Peste Des Petits Ruminants (PPR) in Goats

The present study describes pathological findings in 25 cases of Peste des Petits Ruminants (PPR) infection. Out of 462 goats carcass examination, in which 262 cases were from slaughtered animals and 200 cases were from fallen animals. On post mortem examination, pathological findings included erosive ulcerative stomatitis, severe haemorrhagic enteritis along with enlarged mesenteric lymph node. The large intestine of affected animals showed pathognomonic haemorrhages like zebra striping (zebra marking) and ecchymotic haemorrhages in abomasum. Histopathological lesions were characterized by syncytial cell formation, infiltration of mononuclear cells with eosinophilic intranuclear inclusions in alveolar macrophages of lungs section. Gross and histopathological lesions were suggestive for PPR infection, which was further confirmed from the specialized PPR laboratory in Mukteshwar (Uttarakhand) Regional Station of ICAR, IVRI using s-ELISA.


SHORT COMMUNICATION
Peste des Petits Ruminants (PPR), also known as Goat Plague, occurs in small ruminants. Disease is caused by a virus belonging to genus Morbillivirus, family Paramyxoviridae and it is antigenically related to rinderpest disease (Gibbs et al., 1979). PPR has become endemic in India since it was first reported from the south Indian state Tamil Nadu in 1987 . Both PPR and rinderpest viruses have been found to cause similar diseases in small ruminants (Diallo et al., 1989). On the basis of data reported by Government of India, average annual economic loss of ` 125.67 lacs in goats is due to PPR infection (Singh et al., 2014). The current investigation was aimed to describe PPR infection in fallen goats employing gross and microscopic pathology.
A total of 462 lungs and others affected organs sample from goats were collected during August 2015 to April 2016 from various sources such as Bareilly and Delhi slaughterhouses and post-mortem facility of IVRI. Out of 462 lungs, 262 cases were from slaughtered animals and 200 were from fallen animals. Appropriate representative tissue samples from lungs were collected in 10% neutral buffered formalin. During histopathological processing, the thin pieces of fixed tissue samples were kept in running tap water for overnight washing, then dehydration was done through ascending grades of alcohol followed by clearing with acetone and benzene and then embedding in paraffin wax blocks in automatic tissue processor and the tissues were then cut into 4-5 μm thick paraffin sections by microtome and stained with routine haematoxylin and eosin technique (Bancroft and Gamble, 2008).
Out of 462 goats carcasses examination, 25 (5.41%) cases were confirmed positive for PPR from the specialized PPR laboratory in Mukteshwar (Uttarakhand) Regional Station of ICAR-IVRI.During necropsy, most of the carcasses were found to be dehydrated and emaciated with sunken eyes, but some goats were in good body condition at early infection. Most dead goats showed necrotizing and erosive stomatitis. The buccal cavity revealed erosive and ulcerative lesions on the tongue, gums, dental pads, hard palate and soft palate (Fig. 1). Grossly, respiratory tract examination revealed frothy exudates and congestion in tracheal mucosa. The lung showed pneumonic lesions in all necropsied goats. The most commonly affected lung lobes were apical and cardiac lobes which revealed red hepatization (consolidation) and congestion (Fig. 2). In three goats, severe consolidation with fibrin deposition on the lobes was also recorded. In addition, emphysema was also observed. On cut sections, lungs showed large quantities of frothy exudates indicative of pulmonary edema. In intestines, moderate to severe haemorrhagic enteritis characterized by hyperaemic thickened intestinal mucosa with haemorrhagic intestinal contents were recorded. Mesenteric lymph nodes were most commonly affected which were generally enlarged, oedematous and congested (Fig. 3). In the digestive tract, abomasums of three goats revealed ecchymotic haemorrhages (Fig. 4) and large intestine of affected animals showed pathognomonic zebra striping (zebra marking) (Fig. 5).  The gross lesions observed in the present study included erosive ulcerative lesions in the mouth, respiratory and gastrointestinal tract were also reported earlier in PPR infected in sheep and goats by many workers (Chauhan et al., 2011;Jagtap et al., 2012;Rosemary et al., 2013;Patel et al., 2015;Singh et al., 2017). In the presents study, pneumonic lungs were observed probably due to descending upper respiratory infection of PPR complicated by secondary bacterial infection (Rosemary et al., 2013).
Microscopic examination of the lungs section of affected animals showed varying degrees of lesions in parenchyma. The alveolar and bronchial lining epitheliums were showed hyperplasia. There was thickening of interalveolar septa due to increased infiltration of lymphocytes, macrophages and variable sized syncytial giant cells (Fig. 6). These lesions were shown similarity with the earlier observations of various researchers (Jagtap et al., 2012;Maina et al., 2015;Patel et al., 2015). In addition, some cases of the syncytial cells showed the presence of eosinophilic intranuclear inclusions in the alveolar macrophages (Fig. 7). In the present study, presence of syncytial cells and eosinophilic intranuclear inclusions were supported by the earlier reports (Islam et al., 2001;Kumar et al., 2004).
Patho-morphological lesions were suggestive for PPR infection, which was further confirmed by specific sandwich ELISA test using PPR specific monoclonal antibody (clone 4G6) to an epitope of nucleocapsid protein in specialized PPR laboratory in Mukteshwar (Uttarakhand) Regional Station of ICAR, IVRI. In the present study, confirmatory diagnosis based on s-ELISA has similarity with the earlier observations of various researchers Mahajan et al., 2017)

CONCLUSION
The present study concluded that the post-mortem and patho-morphological finding were suggestive of PPRV infection in goats, which was confirmed by the detection of PPRV antigen in post-mortem samples using the s-ELISA by the specialized PPR laboratory in Mukteshwar (Uttarakhand) Regional Station of ICAR-IVRI.