Atypical Parapoxvirus Infection in Sheep

Abstract

This report describes the clinical and laboratory findings for 5 sheep from 3 different flocks with extensive proliferative skin lesions grossly resembling warts on the distal limbs. The lesions affected the front and rear extremities in all sheep, and 2 sheep also had lesions around the head. The sheep exhibited signs of pain when the lesions were touched, and most sheep were reluctant to move. Various empirical treatments, including systemic antibiotics, topical antibiotics, and antifungal ointments, were administered without clinical improvement. Diagnostic tests including skin biopsy and histopathology, examination of skin scrapings, bacteriology, mycology, electron microscopy of lesions, and immunohistochemical analysis demonstrated that the lesions were the result of parapoxvirus infection. All 5 animals were euthanized either because of the lack of resolution of clinical signs or a decision by the owner. These animals illustrate an atypical presentation of parapoxvirus infection in sheep (orf, contagious ecthyma, and scabby mouth). The infection appeared to be minimally contagious; however, the lesions did not spontaneously resolve. This appears to be the 1st report of such lesions in multiple sheep in North America, although similar lesions have been reported in Israel and the United Kingdom.

Bovine Papillomavirus 1 Gets Out of the Flock: Detection in an Ovine Wart in Sicily

“…This factor might also be taken into consideration in our case, where a latent infection could have been triggered, leading to the formation of a papilloma instead of a sarcoid. Contagious ecthyma caused by the Orf virus (OV) in sheep mostly causes pustular dermatitis on muzzles and udders; in the atypical form, however, the infection causes extensive proliferative skin lesions, grossly resembling warts [ 42 , 43 , 44 ]. Furthermore, evidence of co-infections between poxviruses and papillomaviruses within the same lesion have been described [ 44 , 45 ].…”

Activities of Acyclic Nucleoside Phosphonates against Orf Virus in Human and Ovine Cell Monolayers and Organotypic Ovine Raft Cultures

“…It is commonly a self-limiting disease that resolves within 6 to 8 weeks; but complications can include bacterial infections, regional lymphadenopathy, lymphangitis, erythema multiforme, and bullous pemphigoid (11,23,24). In animals and humans, especially in burned and immunocompromised subjects, extensive and recurrent lesions have been described; these lesions result in the development of giant orf or tumor-like lesions (15,16,28,31). While no treatment except for antibiotic therapy to prevent secondary bacterial infections is required for the self-limiting forms of the disease, in the complicated forms, cryotherapy, excision of the mass, and in the worse cases, amputation may be necessary (6).…”

Pseudocowpox virus infection in an American bison (Bison bison)

“…Cases of severe atypical PPV infections were previously reported in sheep from the United States [ 25 ]. These atypical cases were present in sheep over 12 months of age, characterized by lesions similar to classic orf but more severe, did not resolve spontaneously, and led to debilitating conditions in all affected sheep [ 25 ]. Diagnosis of PPV was made based on histological and electron microscopic examination but lacked molecular characterization.…”