Parapoxvirus

Parapoxviruses belong to the Poxviridae family. Like all members of that family, they are oval, relatively large, double-stranded DNA viruses. Parapoxviruses have a unique spiral coat that distinguishes them from other poxviruses. Parapoxviruses infect vertebrates.

Not all parapoxviruses are zoonotic. Notable zoonotic hosts of Parapoxvirus include sheep, goats, and cattle.

The most recent species of Parapoxvirus has been found in New Zealand Red Deer. There are also some tentative species in the genus, including Auzduk disease virus, Chamois contagious ecthyma virus, and Sealpox virus.

Impact
Parapoxviruses cause infection of cows, sheep, goats, and red squirrels worldwide. They tend to cause lesions which range in size depending on the case. Between 1990 and 1995, there was a mean of 15 cases reported annually. This is a significant decline from the annual mean of 46 cases between 1968 and 1978.

Some authors believe that the infection is much more common than reported, as it may not appear to be a serious infection.

Seasonal fluctuations
Most reports indicate a higher frequency of human infections during the spring and autumn, presumably due to the seasonal slaughtering of susceptible animals. However, others show a higher occurrence in winter. This may be attributed to the use of gorse, an animal feed that may cause trauma, thereby leading to infection.

Properties
Virions are enveloped and have a diameter of 160-190 nm. They are about 250-300 nm long, and have a regular surface structure; tubules with a diameter of 10-20 nm form a criss-cross pattern.

The virions have one molecule of double-stranded DNA, putting into the Group I category for virus classification purposes.