Ad4

Ad4 refers to adenovirus type 4, a serotype of human adenoviruses. It is a non-enveloped, icosahedral virus with double-stranded DNA belonging to the family Adenoviridae and genus Mastadenovirus. Ad4 infects mucosal surfaces of the respiratory tract and conjunctiva and is transmitted through respiratory droplets, direct contact, and contaminated surfaces.

Clinical disease caused by Ad4 ranges from mild upper respiratory illnesses to more severe pneumonia, particularly in young children, older adults, and immunocompromised individuals. Common symptoms include fever, sore throat, cough, and sometimes conjunctivitis. Outbreaks have been reported in schools, camps, and military settings.

Epidemiology and transmission: Ad4 is globally distributed and frequently implicated in acute respiratory infections. In some regions and populations, especially closed or semi-closed groups, outbreaks can occur more regularly. Most infections are self-limited and resolve without specific therapy.

Diagnosis and treatment: Diagnosis is typically achieved by nucleic acid amplification tests (PCR) from respiratory specimens, viral culture, or antigen detection in certain settings. Management is primarily supportive. There are no widely used antiviral treatments for routine Ad4 infection, though cidofovir may be considered in severe or disseminated disease in immunocompromised patients.

Prevention: A live, oral vaccine against Ad4 and Ad7 has been used to protect military personnel from acute respiratory disease caused by these serotypes. The vaccine is administered as part of military preventive medicine programs and is not routinely used in the civilian population.

History: Adenovirus type 4 was identified in the mid-20th century and has since been a focus of surveillance, outbreak control, and vaccine development in human populations.