Abstract
Circular whitish granular lesions, 5–12 mm in diameter, were observed on the skin and fins of a wild northern pike, Esox lucius , caught in a lake in the Republic of Ireland. Histological examination of the lesions revealed hypertrophied cells in the epidermis with deeply basophilic enlarged nuclei and dark‐staining granular material in the cytoplasm. Transmission electron microscopy of these cells revealed naked hexagonal herpes‐like virus nucleocapsids (97 ± 7 nm) in their nuclei while the cytoplasm contained multiple aggregates of enveloped viral particles. This is the first report of herpes‐like virus particles in northern pike originating outside North America, where esocid herpesvirus‐1 (EsHV‐1) has previously been reported. Shared clinical, histological, morphological and epidemiological findings suggest that the observed particles in this report may also be EsHV‐1.