Poxviral zoonoses

The family Poxviridae comprises two subfamilies, Chordopoxvirinae, the poxviruses of vertebrates, and Entomopoxvirinae, the poxviruses of insects. Within the subfamily Chordopoxvirinae there are eight genera, distinguished from each other by their DNA restriction maps, the absence of cross protection, and other biologic properties. There are also a few unclassified viruses, all of them derived from wildlife (Table 1). Twelve poxviruses cause disease in humans; two of these diseases, smallpox and molluscum contagiosum, are specifically human; smallpox is now extinct. Three orthopoxviruses, four parapoxviruses, and one yatapoxvirus are known to cause zoonotic infections; the other yatapoxvirus has caused lesions in inoculated humans (Table 2). Human infections with most of these viruses are occupational diseases, occurring in veterinarians, animal handlers, milkers, and shearers; only monkeypox, tanapox, and occasionally cowpox occur as non-occupational zoonotic infections. Table 2 Poxviral Zoonoses Genus Species Animal reservoir Disease in humans Geographic distribution Symptomatology Orthopoxvirus Cowpox virus Monkeypox virus Rodents, cats, cows Squirrels, monkeys Europe Central and western Africa Local pustule Generalized exanthematous disease Vaccinia virus (buffalopox virus) Laboratory product Water buffaloes Formerly worldwide India, formerly Egypt, Indonesia Local pustule (smallpox vaccination) Pustules Parapoxvirus Orf virus Sheep Worldwide Local nodules Bovine papular stomatitis virus Cattle Worldwide Local nodules Pseudocowpox virus Dairy cattle Worldwide “Milker’s nodules” Sealpox virus Seals (several species) Canada^a Local nodules Yatapoxvirus Tanapoxvirus Rodents, monkeys Central and eastern Africa, U.S.A.b Local nodules Yabapoxvirus Monkeys U.S.A.^b After inoculation, local nodules ^a From captive seals, collected in Nova Scotia, Canada. ^b In 1965-1966, from monkeys in laboratory colonies in the U.S.A.