Two<unk> s are well established.<unk> -1 and<unk> -2 are both involved in actively spreading epidemics, affecting 15–20 million people worldwide.<unk> -1 is the more clinically significant of the two: at least 500,000 of the individuals infected with<unk> -1 eventually develop an often rapidly fatal leukemia, while others will develop a debilitative myelopathy, and yet others will experience uveitis, infectious dermatitis, or another inflammatory disorder.<unk> -2 is associated with milder neurologic disorders and chronic pulmonary infections. In the United States,<unk> -1/2 seroprevalence rates among volunteer blood donors average 0.016 percent. No specific illnesses have yet been associated with<unk> -3 and<unk> -4.
Human T-lymphotropic virus
Kaposi's sarcoma-associated herpesvirus
Oncolytic adenovirus
Trichodysplasia spinulosa polyomavirus
Oncovirus
Human betaherpesvirus 7
Human betaherpesvirus 5
Xenotropic murine leukemia virus–related virus