Discussion
The adenoviruses are a family of a globally distributed, perennial, DNA
viruses that commonly cause a self-limiting febrile illnesses in
children. It is the most common cause of viral conjunctivitis in
children older than 6 years.3 Fatal infections can
occur in immunocompromised hosts with a low cell mediated immunity, and
are rarely seen in healthy individuals.4 Over sixty
human adenovirus serotypes, further classified into seven species (A-G)
based on biologic properties, have been described. Species B serotypes 3
and 7 are the most common. Species B, C with serotypes 5, 7, 14, and 21
are primarily responsible for a severe infection.5Infections are prevalent in daycare centers and crowded settings. The
mode of transmission is via aerosol, fecal-oral route, or contaminated
fomites. Long periods of survival on inanimate surfaces and resistance
to lipid disinfectants due to its non-enveloped structure contribute to
a faster and wider spread. Most individuals have a serologic evidence of
prior infection during the first decade of their
life.6
The age and immunocompetency of the host dictate the range of clinical
manifestations in the patient. While respiratory tract infections like
pharyngitis, coryza, and pneumonia are common, gastrointestinal,
ophthalmologic, and genitourinary involvement can also be seen.
Adenovirus can cause severe hemorrhagic conjunctivitis which can mimic
bacterial cellulitis leading to an unnecessary antimicrobial treatment
such as seen with our patient.7 The illness usually
lasts five days to two weeks with further lengthening in the case of a
bacterial super-infection. The classic presentation is that of a
pharyngo-conjunctival fever with follicular conjunctivitis, febrile
pharyngitis, cervical adenitis, and associated systemic manifestation,
leading to a clinically indistinguishable picture from the group A
streptococcal infection.8 A whitish membrane seen on
the palpebral conjunctiva (pseudomembrane), along with eyelid edema is a
common physical examination sign seen in such
patients.7 Ophthalmologic involvement in the form of
epidemic keratoconjunctivitis, caused by species D serotypes 8, 19, and
37, is a serious infection characterized by blurry vision, bilateral
conjunctivitis, preauricular adenopathy, and painful corneal
opacities.8 The adenoviral disease spectrum may
include an exanthem, hemorrhagic cystitis (species B serotypes 11 and
21), otitis media, pertussis-like syndrome, bronchiolitis, myocarditis,
viral myositis, acute respiratory distress syndrome,
meningoencephalitis, hepatitis, tubulointerstitial nephritis,
urethritis, neutropenia, and disseminated intravascular
coagulation.9 Immunocompromised hosts, such as
patients with hematopoietic stem cell or solid organ transplant, may
have a higher risk of disseminated infection causing pneumonia,
hepatitis, colitis, nephritis, and encephalitis.4
Adenoviral antigen or polymerase chain reaction assays can be used to
detect the virus from an eye swab sample.4 Serum DNA
testing via microbial cell-free DNA test offers rapid identification of
virus, especially when the viral versus bacterial diagnosis is in doubt,
thus avoiding cumbersome viral culture which is not high
yielding.10,11 Next generation sequencing creates full
sequences from the free or fragmented DNA present in the plasma, and
compares it with stored DNA sequences in the database to find an exact
match. Such technique can scan for the presence of DNA of multiple
organisms, including bacterial, fungal, parasitic, and viral in one
serum sample.12 Shorter turnaround time when compared
to traditional culture provides an additional benefit. Currently, the
sensitivity in detecting viral infections of distant organs via next
generation sequencing is still unclear. Sensitivity is better for
disseminated infections, where micro-organism is expected to cross
plasma. Early and accurate identification of viral etiology helps to
de-escalate antibiotics sooner thus reducing the adverse effects. It
also allows initiation of topical steroids, which otherwise would be
contraindicated in a typical bacterial infection, leading to faster
recovery. While supportive therapy and steroids are mainstay in
treatment, the re-introduction of adenovirus vaccination in military
recruits showed significant reduction in the incidence of adenovirus
related febrile respiratory illness.9,13