Adenoviruses infect birds, humans, and many other mammals and other organisms. They usually cause respiratory infections, but they can also cause conjunctivitis, gastroenteritis, cystitis, and rash illness. Adenoviruses are divided into four genera: Aviadenovirus (which infects birds), Mastadenovirus (which infects mammals), Atadenovirus and Siadenovirus (which infect a variety of organisms).
They can survive for long periods of time outside the body due to an unusually high resistance to chemical or physical agents and adverse pH conditions. Transmission is usually through direct contact, fecal-oral transmission, or waterborne transmission.