Adenoviruses are a family of viruses that can infect people of all ages. These infections most often affect the upper respiratory tract. They are slightly more common in the late winter, spring, and early summer months, but may also develop at other times of the year. Different adenoviruses cause illnesses affecting different areas of the body. Some strains cause infection of the lining of the eyelids, breathing passages, and lungs, while others affect the bowel or bladder.

The adenoviruses are spread by person-to-person contact, including transfer through secretions that are sneezed or coughed into the air or onto hands and faces. Some adenoviruses are present in the bowels and in the stools. A person getting the virus on their hands while washing or using the bathroom can spread these viruses. The virus can be passed from one set of hands to the next and then to the mouth or nose or into the eyes. Children who are in child care, especially those from 6 months to 2 years of age, have a greater chance of catching these viruses.