Squirrelpox virus

Squirrelpox virus (SQPV) is a virus that causes the fatal disease squirrelpox in United Kingdom and Republic of Ireland red squirrels. The virus is often carried by grey squirrels from North America, which rarely die from the disease. Elsewhere in the Red Squirrel's European range, either the grey squirrel does not occur or it lacks the poxvirus.

Overview

Grey squirrels very rarely die from this disease as their population has developed immunity having been exposed to the virus for many years; however, they are still carriers of the infection and can spread the disease to red squirrels. In sharp contrast, there are no known red squirrels that have developed immunity to the disease, and the mortality rate for untreated infected squirrels in the wild appears to be 100%, most dying within 4–5 days of being infected.

There has been some more recent anecdotal evidence on resistance to squirrel pox in the red population including the finding of a healthy red squirrel with antibodies to the virus in Cumbria. However the mortality rate is still considered severe, and certainly capable of local extinction of red squirrels in areas that succumb to the disease.

Taxonomy

The ICTV abbreviation for Squirrelpox virus is SQPV. The classification of the virus is still under debate, and the recent studies have suggested that it should be grouped into a clade of its own rather than Parapoxvirus.

Transmission

The virus can spread through contact with the infected lesions or contaminated crusts, and can also be carried by mosquitoes. Fleas are another vector for the disease.