Adenovirus is a medium-sized (90-100 nm) noneveloped icosohedral virus containing double-stranded DNA. There are 49 immunologically different types that can cause human infections, ranged through 6 subspecies (A – F). Adenovirus is usually stable to chemical or physical agents and adverse pH conditions so that it can survive for a longer time outside of the body.
Clinical features: Adenovirus is an important respiratory tract agent that can produce pneumonia and bronchiolitis in small children. However, depending on the infecting serotype, it may also cause other illnesses, such as gastroenteritis, conjunctivitis or rash illness. Symptoms of respiratory illness caused by this virus range from the common cold syndrome to pneumonia and bronchitis. Immunosuppressed patients are more susceptible to severe complications of adenovirus infections.
Diagnosis: Adenovirus infections can be diagnosed in the laboratory by three classical methods: direct antigen detection on clinical specimens; culture techniques to isolate and identify the virus and serological tests to measure rises in antibody levels. IgM detection is more efficient in infants (primoinfections), whereas in adult populations establishing seroconversion is needed. The most widely accepted tests in serological diagnosis are complement fixation (CF), indirect immunofluorescence assay (IFA) and ELISA, all measuring antibodies against common adenovirus antigens. The ELISA and IFA are much more sensitive and convenient than CF and has the added advantage of being readily adapted for detection of specific immunoglobulin classes IgG and IgM.
Treatment: Most infections are mild and require no therapy. As there is no virus-specific therapy, severe adenovirus illness can be managed only by treating symptoms and complications of the infection.