Swimming may be infected with adenovirus. Spread of adenovirus can invade the body through the respiratory tract, the digestive tract and the conjunctiva of the eyes. Epidemics can occur in dense populations, such as public swimming pools and hospitals. Therefore, it is possible to get adenovirus infection while swimming. The incubation period of adenovirus infection is about 2 to 14 days, the length of which depends on the serotype of the virus and the route of transmission. Adenovirus infections can occur throughout the year, but mostly in winter and spring. Adenoviruses can cause many forms of illness, including acute upper and lower respiratory tract infections, fulminant conjunctivitis, viral gastroenteritis, acute hemorrhagic cystitis, and encephalitis, with symptoms such as fever, cough, nausea, vomiting, and headache. More than 80% of adenoviral infections occur in children younger than 4 years of age. Most adenoviral infections are self-limiting, but a few can be fatal. Adenovirus infections are treated with symptomatic and antiviral therapy, such as ribavirin and cidofovir, and there is no effective vaccine. Prompt medical attention is recommended if there are any uncomfortable symptoms.