Definition of Adenovirus
Adenovirus definition - medical term 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 waterborne 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.
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