Infection, adenovirus

Infection with one of a group of viruses responsible for a spectrum of respiratory disease as well as infection of the stomach and intestine (gastroenteritis), eyes (conjunctivitis), and bladder (cystitis) and rash. Adenovirus respiratory diseases include a form of the common cold, pneumonia, croup, and bronchitis. Patients with compromised immune systems are especially susceptible to severe complications of adenovirus infection. Acute respiratory disease (ARD), a disorder first recognized among military recruits during World War II, can be caused by adenovirus infections under conditions of crowding and stress.

Adenoviruses are transmitted by direct contact, fecal-oral transmission, and occasionally waterborne transmission. Some types of adenoviruses are capable of establishing persistent asymptomatic infections in the tonsils, adenoids, and intestines. Shedding of the virus can occur for months or years after the initial infection.

Some types of adenoviruses are endemic (constantly present) in some parts of the world, and infection is usually acquired during childhood. Other types of adenoviruses cause sporadic infection and occasional outbreaks. For example, epidemic keratoconjunctivitis (eye infection) is associated with certain adenoviruses (serotypes 8, 19, and 37). Epidemics of fever with conjunctivitis are associated with waterbourne transmission of some adenovirus types, often centering around inadequately chlorinated swimming pools and small lakes. ARD is most often associated with adenovirus types 4 and 7 in the US. Enteric adenoviruses 40 and 41 cause gastroenteritis, usually in children.

The clinical spectrum of disease associated with certain adenoviruses depends on the site of infection. For example, infection with adenovirus 7 acquired by inhalation is associated with severe lower respiratory tract disease, whereas oral transmission of the virus typically causes no or mild disease.

Outbreaks of adenovirus-associated respiratory disease have been more common in the late winter, spring, and early summer. However, adenovirus infections can occur throughout the year.

Adenovirus infection is diagnosed in the laboratory by antigen detection, polymerase chain reaction (PCR), virus isolation, and serology. Since adenovirus can be excreted for prolonged periods, the presence of virus does not necessarily mean it is associated with disease.

There are no effective medications to treat adenovirus infection. Adenovirus infections typically do not cause permanent problems or death. The exceptions are infection in an immunodeficient patient and ARD which can be fatal.

Vaccines were developed for adenovirus serotypes 4 and 7, but were available only for preventing ARD among military recruits. Beginning in 1971, all (American) military recruits were vaccinated against adenovirus, but the sole manufacturer of the vaccine halted production in 1996. And as supplies dwindled, adenoviral infection reemerged in the US military.

Strict attention to good infection-control practices is effective for stopping nosocomial (hospital-based) outbreaks of adenovirus-associated disease, such as epidemic keratoconjunctivitis. Maintaining adequate levels of chlorination is necessary for preventing swimming pool-associated outbreaks of adenovirus conjunctivitis.

The virus is approximately 70 nanometers in diameter and contains DNA. Over 40 types of adenoviruses have been recognized. Adenoviruses can be genetically modified for use in gene therapy.