Diagnosis and Management of Scrapie in Post Mortem Goats by Immunohistochemistry

The main objective of this study was to contribute to the annual passive surveillance for this pathology, since the goats are a species considered reservoir for the prion. A class of pathologies known as transmissible spongiform illnesses (TSEs), which affect both humans and animals, includes scrapie, a neurological disease with a slow and deadly course that affects sheep, goats, and mouflons. Given that immunohistochemistry (IHC) is the globally accepted technique for identifying classical scrapie in goats—a species thought to be a potential zoonotic disease reservoir. Chile in relation to bovine spongiform encephalopathy (BSE), is classified as a disease-free country. Scrapie is actively monitored for the sheep, but passively for the caprine species, which is why this study was carried out in slaughtered goats in the central north of the country (IV Region), to provide information to the surveillance system for this disease. Fifty brains of goats older than 2 years were used, regardless of race or gender. The obex was taken from each of them, two serial histological sections were obtained, one used for the staining of Hematoxylin and Eosin (H/E) (50 cuts), which allowed us to observe lesions and to evaluate the aptitude of the samples. The other one was used for immuno histo chemistry (IHC) (50 cuts), which allows to locate prions in situ, using a commercial kit and the technique described by Manning et al. [1]. For a correct diagnosis, 4 controls were used, 2 positive (1 ovine and 1 caprine) and 2 negative (1 ovine and 1 caprine), provided by an International Reference Center. Analysis of the 50 H/E histological sections indicated that all were eligible for the IHC technique, and non-specific lesions (38/50) were found, such as focal haemorrhage, perivascular infiltrate and pigments, all of which are not attributable to prions. Due to the absence of immunostaining, which is indicated by a red granular precipitate and was present in the positive controls, all homologous histological sections of the samples and the negative controls were categorized as negative to classic scrapie using the IHC technique. The results obtained in this work validate the application of the IHC technique at the level of obex, as a method of diagnosis of classic goat scrapie in the country.