A genus of double-stranded DNA viruses of the family Adenoviridae that infect mammals and birds, spreading through contaminated water and foods such as shellfish harvested from polluted waters. Infection may be asymptomatic or cause gastroenteritis, respiratory illness or eye infections. Adenoviruses are notably hardy — non-enveloped, resistant to many disinfectants and persistent in the environment — which makes them useful indicators of viral contamination in water supplies. Foodborne outbreaks are less common than with norovirus, but their toughness keeps them on the watch list for water and shellfish safety.