Abstract
In 2001, over a 1-month period, eight Barbary red deer (Cervus elaphus barbarus) were euthanatized due to clinical signs resembling malignant catarrhal fever of domestic cattle. Age ranged from 1–8 years. Six were male and two were female. The deer were housed together in a large outdoor exhibit with 4 other species of ruminants (Ankole cattle, Bos primigenius f. taurus; Jackson’s hartebeest, Alcelaphus buselaphus jacksoni; sand gazelle, Gazella subgutturosa marica; scimitar-horned oryx, Oryx dammah). The last movement of a Barbary red deer into the enclosure occurred 1 year prior to onset of clinical signs.
Clinical signs were nasal discharge, ocular discharge or swollen eyelids, swollen conjunctivae, cough, lethargy, depression, shaking of the ears or head, and skin ulcers. All animals were euthanatized within 2 days of the development of clinical signs.
Gross lesions were of variable severity and distribution and consisted of oral cavity ulcers and erosions; ulcers and erosions of skin around the mouth and nasal planum and in other areas of the body; yellow-white ocular discharge; yellow-white nasal discharge; enlarged and reddened mandibular, retropharyngeal or cervical lymph nodes; dark red intestine; abscessed tonsil; mottled red-purple lung; and reddened laryngeal, pharyngeal or tracheal mucosa. All deer were in good body condition. Lesions tended to be more extensive and severe in those deer euthanatized at the beginning of the outbreak.
Microscopically, lesions in the skin, oral cavity, and conjunctiva consisted of erosions and ulcers with infiltrates of neutrophils and lymphocytes. Inflammatory infiltrates were also present in some regions where ulcers and erosions were not present. Lymphocytes predominated and infiltrates were most dense in the superficial dermis and submucosa with extension into the overlying epithelium (interface dermatitis). Some vessels had perivascular inflammatory cells (predominantly lymphocytes). Lymphoid infiltrates were also associated with some bronchi, bronchioles and in trachea. Vasculitis, typical of malignant catarrhal fever in domestic cattle, was not seen in any cases.
Attempts to isolate a virus were unsuccessful. In situ hybridization using an alcelaphine herpesvirus (AlHV) gene sequence found in both AlHV-1 and AlHV-22 and immunohistochemistry (using an antibody to AlHV-2)7 demonstrated virus within oral submucosal salivary glands deep to areas of ulceration and inflammation. No staining occurred in unaffected areas. sing PCR and herpesvirus primers herpesvirus was found in all affected deer.1,2,6,8 Tissues sampled included peripheral blood leukocytes, conjunctiva, intestine, kidney, liver, lymph node, lung, nasal cavity, oral mucosa, and spleen. Cloned DNA sequences were compared to GenBank data for other viruses in the malignant catarrhal fever group and the following percent homologies were obtained: AlHV-2 (93–94%), AlHV-1 (77–78%), ovine herpesvirus-2 (67%), deer MCF virus (65%). PCR assays for bovine viral diarrhea virus, foot and mouth disease virus, vesicular stomatitis virus, and ruminant alphaherpesviruses (BHV-1 and BHV-5) were negative.2-4,7 The herpesvirus identified in these red deer is most similar to AlHV-2, but it is not yet known whether this may be a new virus. The source of the infection has not been identified.
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