Atypical Manifestation of Cutaneous Fowlpox in Broiler Chickens Associated with High Condemnation at a Processing Plant

Abstract

The present case is an unusual report of cutaneous fowlpox with an atypical appearance and incidence in broilers. Gross skin lesions were noticed in 41-day-old commercial broilers during the veterinary inspection at a processing plant in the north of Iran. The skin lesions were only observed on feathered skin areas of the broilers and remained unnoticed until slaughter. Round, nodular or coalescent, elongated, reddish-brown proliferative lesions were mainly located on the back, thighs, and proximal areas of the neck of broilers. Nonfeathered skin, including the wattle, comb, eyelids, and legs, were not affected. This condition incurred high losses due to a 5.3% condemnation and trimming of carcasses. Cutaneous lesions were sampled for histopathology and molecular virology for further investigations. Histopathology revealed multifocal necrotic dermatitis with epidermal eosinophilic cytoplasmic inclusion bodies in the skin lesions. Molecular investigations confirmed the presence of fowlpox virus (FWPV) in the proliferative lesions, with further investigations identifying two FWPV genome populations, one carrying a portion of the reticuloendotheliosis virus (REV) and the other a nearly complete REV provirus. Furthermore, the 4b core protein gene-based molecular analysis clustered the field virus into clade A of the genus Avipoxvirus.