Poxvirus infection in a cat with presumptive human transmission

The present report describes a case of generalized cowpox virus infection with necrotizing facial dermatitis in a cat and a likely transmission to an animal keeper. The viral aetiology was confirmed by histopathology, immunohistochemistry, PCR, virus isolation, DNA sequencing and electron microscopy. Histopathological examination of the cat's skin revealed a severe, necrotizing dermatitis with ballooning degeneration and hyperplasia of epithelial cells with pathognomonic cytoplasmic eosinophilic inclusion bodies. Additionally, at post-mortem examination, a systemic poxvirus infection was detected affecting pancreas, thymus, lymph node, liver and lung. The human patient's skin biopsy revealed an ulcerative dermatitis with epidermal hyperplasia and ballooning degeneration. Serological investigation displayed a high orthopoxvirus-specific antibody titre in the human patient. Environmental factors increase the natural reservoir host population for cowpox viruses, such as voles, which results in a higher risk of infection for cats and subsequently for humans. Due to this zoonotic potential, a cowpox virus infection must be considered as an aetiological differential in cases of necrotizing dermatitis in cats.