The signs and symptoms of adenovirus infections are similar to those of the common cold. The affected person may develop a stuffy or runny nose as well as a sore throat (pharyngitis), eyelid lining inflammation (conjunctivitis), infection of the small breathing tubes in the lungs (bronchiolitis), pneumonia, a middle ear infection, or fever. Some children may have a harsh cough, similar to that of whooping cough. Sometimes there is bleeding into the lining that covers the eyes. This virus may cause eyes to look very frightening, but vision is not affected. Children infected with some strains of adenovirus develop inflammation of the stomach and intestinal tract, which can cause diarrhoea and abdominal cramps (gastroenteritis). This virus can also infect the bladder and cause blood in the urine and pain when urinating. Occasionally, the virus causes infection in or around the brain (meningitis or encephalitis). In patients with an organ transplant or other conditions in which the immune system is weakened, adenovirus infection can be quite severe and result in an overwhelming infection and death.
Once a person is exposed to the virus, there is an incubation period of 2 to 14 days before symptoms appear. The incubation period for gastroenteritis can range from 3 to 10 days.