Contagious pustular dermatitis is one of the most widespread viral diseases worldwide.It is a poxviral disease of sheep and goats, caused by a Parapoxvirus (Orf virus) affecting alsohumans, camels, cows, and many wild ruminants, and very rarely dogs (1). The disease wasclinically diagnosed from different field cases of sheep and goat in Bistri?a-N?s?ud County,Romania in 2009. Skin biopsies were used for histopathological diagnosis, using the standardtechniques. The slides were prepared and examined inside the Pathology Department ofUASVM Cluj-Napoca. Hematoxylin Eosin (HE) and Trichrom Masson (TM) coloured slideswere used to describe the histological features of the skin infection in lambs. Histologicalanalysis of skin samples was performed with an Olympus BX 41 optical microscope andimage processing was performed using the software CellB. Most significant gross lesion is thelayer of thick brown-gray crust that may be elevated 2-4 mm above the skin surface.Regression usually occurs without medication in 4 weeks. Papillomatous growths, resultingfrom continued epidermal proliferation, sometimes occurred. The lesions observed followingexamination, were typical for pox-virus infections, but more proliferative. We observedvacuolization and increase in volume of keratinocites from the external spinous layer of theepidermis, reticular degeneration (nuclear pyknosis and marked hydropic changes), markedepidermal proliferation (3-4 times the normal thickness, with pronounced elongation of reteridges), intradermal microabscesses and crust formation on the surface. Only in two caseseosinophilic intracitoplasmatic viral inclusions of different sized were observed, whichappeared simultaneously with the reticular degeneration, but they do not persist more than 3-4days, unlike other pox-virus infections. At the dermis, we noticed superficial edema,perivascularitis with abundant neutrophils (probably also due to secondary bacterialinfections), lymphocytes and macrophages. At the surface of the skin, a thick crusty layer wasformed, composed of orthokeratotic and parakeratotic keratin, proteinacous fluid, degeneratedneutrophils and cellular debris. Intraepidermal abscesses were also observed in some cases, asa complication of secondary bacterial infections. Of late, there have been an increasingnumber of reports of new species being affected by the disease, implying a dynamic hostpathogeninteraction (2). The causative agent, orf virus, has to be extensively investigated,owing to its zoonotic importance and ability to cross-infect other species sporadically.
展开▼
