Adenoviruses are the main group of viruses which can be isolated from lymphoid tissues of Waldeyer's tonsillar ring and excrement from any apparently healthy person. Adenovirus infections affect infants and young children much more frequently than adults. Adenovirus infections are transmitted by direct contact and fecal-oral transmission. Incubation period is 4-5 days.
Outbreaks of adenovirus associated respiratory disease happen more commonly in the late winter; however, adenovirus infection can occur throughout the year. Pharyngoconjunctivitis (pharyngoconjunctival fever) is often seen in infants and young children. Keratoconjuctivitis is a more severe infection that involves both the conjunctiva and the cornea, and can occur after trauma or medical manipulations. Adenovirus often affect the lower respiratory tract as well.