Paratuberculosis in red deer (Cervus elaphus): an immunohistochemical study

In the present study, we compared the utility of immunohistochemistry with serological and histological results for the characterization of Mycobacter ium avium ssp. paratuberculosis (M. paratuberculosis) in tissues of affecte d red deer. Bacterial isolation was considered the standard reference. Samp les were taken from seven clinically affected animals with typical macrosco pic lesions. The enzyme linked immunosorbent assay (ELISA) and the gel diff usion tests (GD) were used for serological determinations. Samples from int estine and mesenteric lymph nodes were processed for bacterial isolation an d histology. M. paratuberculosis was isolated from all the animals. Histolo gically, lymph notes displayed necrosis and mineralization at the cortical and medullar areas. Ziehl-Neelsen stained bacteria were numerous inside mac rophages and Langhans-type giant cells. Giant and epithelioid cells and lym phocytes were prominent at the ileal mucous membrane. The immunostaining of M. paratuberculosis was very clear inside epithelioid and giant cells. Ima ge analysis was carried out to determine the immunostained area. There was total agreement among the methods employed. Immunohistochemistry can be ver y useful when the microorganism cannot be recovered from tissues or faeces.