There are 49 known serotypes of adenoviruses; they cause 5 major infections, all of which occur in epidemics. These organisms are common and can remain latent for years; they infect almost everyone early in life, although maternal antibodies offer some protection during the first 6 months of life.

Adenovirus infections are highly contagious. The types of adenovirus that cause respiratory and intestinal infections spread via respiratory droplets, such as coughing or sneezing, or by fecal contamination. Direct transmission can result from poor hand hygiene between using the bathroom and eating or preparing food, or from poor hygiene after handling diapers. Indirect transmission can occur through exposure to contaminated surfaces or items such as soiled tissues. The virus can live on inanimate objects for several hours. The types that cause conjunctivitis can be transmitted by water, such as swimming pools, by touch, or by sharing contaminated objects, such as towels.

Although the complications associated with adenovirus vary with the area that is infected, the most common complications are acute conjunctivitis, sinusitis, pharyngitis, bronchiolitis, and pneumonia. Acute respiratory disease can be caused by adenovirus during conditions of stress and crowding. Intussusception has occurred in infants with the GI form of infection.

Patients with a compromised immune system or with underlying respiratory or cardiac disease are especially susceptible to severe complications of adenovirus.