Polyomaviridae is a family of viruses whose natural hosts are primarily mammals and birds. 13 species are known to infect humans, while others, such as Simian Virus 40, have been identified in humans to a lesser extent. Most of these viruses are very common and typically asymptomatic in most human populations studied.
All the polyomaviruses are highly common childhood and young adult infections. Most of these infections appear to cause little or no symptoms. These viruses are probably lifelong persistent among almost all adults. Diseases caused by human polyomavirus infections are most common among immunocompromised people.
HPyV7 has been associated in case reports with a skin condition in immunocompromised patients—HPyV7-related epithelial hyperplasia—specifically lung transplant recipients on a regimen of immunosuppressive drugs. The reported skin manifestations consisted of severely pruritic (itchy) velvet-textured plaques initially interpreted clinically as drug side effects. Evidence of actively replicating HPyV7 was identified in affected tissue, supporting the hypothesis that the virus caused the rash.