L'adénocarcinome nasal enzootique chez les ovins dans l'Est algérien.

Abstract

Enzootic nasal adenocarcinoma (ENA) is a contagious neoplasm of the secretory epithelial cells of the nasal mucosa of sheep and goats. The disease is sporadic but often clustered in certain flocks and herds. It is caused by a betaretrovirus named Enzootic Nasal Tumour Virus (ENTV). The purpose of our work is to determine the epidemiological, clinical and anatomopathological profile of enzootic nasal adenocarcinoma in sheep in the east of Algeria (Bordj Bou Arréridj, Sétif, Batna and M'sila). From 2014 to 2021, 98 cases of ANE in sheep were described and submitted to autopsy. Nasal tumours were preserved in 10% formalin. The prevalence of ENA recorded at herd level was 8.57% (21/245) while the individual prevalence was 4.46% (98/2196). The disease was observed in the four regions studied without exception. Rates of 4.20% and 4.51% were recorded in females and males respectively. The average age at onset of ANE was 3.2 years, with extremes of 5 months and 7 years. The animals of 2 to 4 years are the most affected. We noted also that age and sex have no influence on the occurrence of the disease. ANE is observed in this study throughout the year with a slight predominance in autumn and winter. The most clinical signs observed were persistent serous to seromucous nasal discharge (100%), emaciation (72.45%), dyspnoea (54.08%), exophthalmos (46.94%) and deformation of the frontal bone (31.63%) and lacrimal bone (23.46%). On necropsy examination, unilateral (59.18%) or bilateral (40.82%), friable, and pinkish-white tumour masses were observed in the nasal cavities. The size of the tumour was varied from 1.3 to 11 cm. Osteolysis of the frontal and lacrimal bones rates was 54.08%. Histopathological examination showed that 100% of the tumours were adenocarcinomas of low malignant potential. The tumour tissue showed a predominantly acinar architecture. Immunohistochemistry with an antibody specific to the ovine betaretrovirus protein ENTV-env confirmed the viral origin of ANE. Besides a positive labelling of the tumour tissue was observed with the antibodies CK7, AE1/AE3, PCNA, Ki-67, vimentin, S100, NSE and AML. This study shows, for the first time, the presence of ANE in Algeria. This pathology is not well known by all the actors of the sheep industry. Isolation and slaughter of affected sheep remains the best way to eradicate this transmissible cancer.