Viral infections of skin and mucosa produce a wide spectrum of local and systemic manifestations.

• Human papillomavirus (HPV) and molluscum contagiosum virus (MCV) colonize the epidermis of most individuals without causing any clinical lesions. Benign epithelial proliferations such as warts and molluscum occur in some colonized persons, are transient, and eventually resolve without therapy. In immunocompromised individuals, however, these lesions may become extensive, persistent, and refractory to therapy.
• Primary infections with many viruses cause acute systemic febrile illnesses and exanthems, are usually self-limited, and convey lifetime immunity. Smallpox caused severe morbidity and mortality, but no longer occurs because of worldwide immunization.
• Eight human herpesviruses (HHVs) often have asymptomatic primary infection but lifelong latent infection. With host defense defects, herpes viruses can become active and cause disease with significant morbidity and mortality.