Parapoxviruses, little-known zoonotic pathogens.

Parapoxviruses, double-stranded DNA viruses of the Poxviridæ family, are etiologic agents of cutaneaous infectious diseases among farm animals. These highly contagious viruses are responsible for wide outbreaks among livestock. The clinical manifestations are generally mild and consist of cutaneous or mucosal lesions, which resolve spontaneously within a few weeks. However, secondary bacterial or fungal infections on the lesion sites can aggravate the symptoms. Sore lesions located within the oral cavity and on the udders can impair feeding or nursing, thus leading to death. Livestock parapoxviruses can infect humans by direct or indirect transmission and affect mainly farmers, slaughters and veterinarians. Human symptoms generally consist of small cutaneous lesions located at the inoculation points but more severe forms can occur, peculiarly in immunocompromised persons. The parapoxvirus epidemiology is poorly understood: their respective host range and ecology among wild animals are to be clarified. The identification of parapoxviruses among marine mammals suggests that the genetic diversity within the genus is still underestimated.