Hector Valadez
Andrew Wong
Micro 401
Case Study #10: Adenovirus
A 7-year old boy attending summer camp complains of sore throat, headache,
cough, red eyes, and tiredness and is sent to the infirmary. His temperature is 40 oC.
Within hours, other campers and counselors visit the infirmary with similar symptoms.
Symptoms last 5 to 7 days. All the patients have gone swimming in the camp pond.
More than 50% of the people in the camp complain of symptoms similar to those in the
initial case. The Public Health Department identifies the agent as adenovirus serotype
3.
1. Toward which adenovirus syndrome do the symptoms point?
There are approximately 53 different serotypes of adenoviruses some of which
are responsible for approximately 5%-10% of all upper respiratory tract infections in
children and adults. Other serotypes however, can present with different symptoms such
as conjunctivitis (inflammation of conjunctiva), pharyngitis (sore throat), cystitis (bladder
infection), or gastroenteritis (inflammation of GI tract). A common syndrome associated
with adenovirus serotypes 3 and 7 is pharyngoconjunctival fever. Pharyngoconjuctival
fever is a specific presentation of adenovirus that is manifested as: a high fever lasting
4-5 days, pharyngitis, conjunctivitis, enlarged lymph nodes, headache, malaise, and
weakness. In this case study, the patient presents with a sore throat, fever, red eyes,
and tiredness all of which are symptoms directly correlated with pharyngoconjunctival
fever.
2. An outbreak as large as this indicates a common source of infection. What was
the most likely source? What were the most likely routes by which the virus was
spread?
One of the common sources for adenovirus infection is through exposure with
contaminated water sources. Throughout the world adenoviruses have been isolated
from sewage, rivers, lakes, groundwater, drinking water, and recreational bathing waters
Most of the reported outbreaks from contaminated pools in the United States have
resulted in pharyngoconjunctival fevers. It is believed that most water gets contaminated
through exposure to infected fecal matter and mucosal secretions from the eyes and
throat.
Based on this data, a contaminated pond may be the likely source of
contamination at the camp. Furthermore, all the patients complaining of symptoms had
previously gone swimming in the pond.
Adenoviruses can easily be transmitted through direct contact, fecal-oral routes,
and waterborne routes. When the patients went swimming their mucosal membranes
may have directly come into contact with the contaminated water by opening their eyes
underwater or by accidentally aspirating or drinking the pond water. Towel sharing is
another factor whereby fomites can spread from one individual to another. Lastly, since
the patients were in a camp and living in close proximity to each other one infected
individual can easily transmit it to another via aerosols or by contaminating surfaces and
exposing others to these fomites.
3. What physical properties of the virus facilitate its transmission?
The ability of adenovirus to be transmitted via multiple routes (aerosol, fecal oral,
direct contact, fomites and contaminated water) is attributed to its unusual stability under
various physical, chemical, and pH conditions allowing it to remain viable outside of the
human body as fomites for prolonged periods of time. As a result, individuals coming
into contact with contaminated objects or water can easily become infected. Adenovirus
can be stable in temperatures up to 56oC and in acidic environments of pH 5-6.
Adenovirus has double stranded DNA which makes its genome more stable by being
less susceptible to breakdown. The virus is also non enveloped which makes it resistant
to lipid solvents and more resistant to adverse chemical and acidic conditions. This
resistance allows them to be able to resist the harsh environment of the gastrointestinal
tract.
4. What precautions should the camp owners take to prevent other outbreaks?
Since the major source of infection was the contaminated pond, the first thing
owners should do to prevent further outbreaks is to frequently disinfect the pond by
using chemicals such as chlorine. Research has shown that properly chlorinating pools
or ponds is effective against preventing and also treating adenovirus contamination in
water. Other disinfectants that have been shown to work are 1% sodium hypochlorite,
2% glutaraldehyde, and 0.25% sodium dodecyl sulfate. Maintenance crews could also
be hired to properly clean all the living quarters and bathrooms with disinfectants to kill
the viruses that might be present as fomites on surfaces. Since adenovirus can also be
spread by direct contact new protocol should also be implemented preventing the
sharing of towels between the campers to reduce the spread of the virus from one
individual to the next. Lastly, camp owners can put on classes to educate students
about proper hygiene and encourage students to practice proper hygiene techniques.
5. What sample or samples would have been used by the Public Health
Department to identify the infectious agent, and what tests would be required to
diagnose the infection?
The public health department would have to collect samples from the pond water
and from bodily fluids of the infected individuals. Adenovirus may be isolated from most
bodily fluids; eye swabs, nasal pharyngeal swabs, urine, feces, leukocytes, and the
cerebrospinal fluid. The most reliable source for isolation however, is stool samples.
One effective test for diagnosing adenovirus is the hemagglutinin inhibition assay
(HIA).
This test relies on the cytopathic effect of the adenovirus that causes the
agglutination of erythrocytes in mammalian cells through its hemagglutinin activity. The
virus is first isolated and then cultured in either HEK cells, Hep-2 cells, or primary
monkey kidney cells. After incubation a red spot will be seen at the bottom of the well
plate signifying the presence of agglutinating activity. On the other hand, if the viral
isolate is treated with specific monoclonal antibodies for the hemagglutinin protein before
it is cultured in cells then hemagglutinin activity will be blocked and no agglutination will
be observed.
Another
test
that
may
be
used
is
direct
antigen
detection
by
immunofluorescence. Here a cell sample from the patient is treated with fluorescently
tagged monoclonal antibodies for adenovirus and observed under a fluorescence
microscope. If the virus is present the antibodies will bind to the virus and will be visible
under the microscope. If no virus is present then antibody binding will not occur and
therefore no fluorescence will be observed.
Enzyme-linked immunosorbent assays
(ELISA) have also been used successfully.
Polymerase chain reactions (PCR) can also be used in the diagnosis of
adenovirus. In PCR, the gene coding for the hexon is amplified and used for analysis
because adenoviruses share group-specific antigen epitopes on the inside of the hexon
protein that allows for them to be typed.
References
"Adenovirus." -
Medical-Wiki.
N.p.,
n.d.
Web.
25
Oct.
2012.
<http://www.studentdoc.com/medical-wiki/Adenovirus>.
"AdenovirusFACTSHEET." AdenovirusFACTSHEET. N.p., n.d. Web. 25 Oct. 2012.
<http://www.nlv.ch/Adenovirus/Adenofactsheet.htm>.
"Adenovirus Infections." Adenovirus Infections. N.p., n.d. Web. 27 Oct. 2012.
<http://www.lpch.org/DiseaseHealthInfo/HealthLibrary/infectious/adenov.
html>.
"Adenovirus Infections." HealthyChildren.org. N.p., n.d. Web. 25 Oct. 2012.
<http://www.healthychildren.org/English/healthissues/conditions/infections/pages/AdenovirusInfections.aspx?nfstatus=401>.
"DrGreene.com Putting the Care into Children's Health." Adenovirus. N.p., n.d. Web.
25
Oct.
2012. <http://www.drgreene.com/azguide/adenovirus>.
Environ. Sci. Technol. 2006, 40, 7132-7140 Human Adenoviruses in Water:
Occurrence and
Health
Implications: A Critical Review SUNNY C. JIANG* Department
of Civil and
Environmental Engineering, University of California, Irvine, California 92697
Guidelines for Safe Recreational-water Environments Final Draft for Consultation
Vol. 2:
Swimming Pools,
Spas and Similar Recreational-water Environments
August 2000
CHAPTER 3 MICROBIOLOGICAL HAZARDS
"Haemagglutination Inhibition Test, HAI." Haemagglutination Inhibition Test, HAI.
N.p.,
n.d.
Web. 20 Oct. 2012. <http://virology-online.com/general/Test4.htm>.
J Pharm Sci. 2006 Feb;95(2):237-47. Effect of pH and ionic strength on the physical
stability of
adenovirus type 5. Rexroad J, Evans RK, Middaugh CR. Source Department of
Pharmaceutical Chemistry, University of Kansas, Lawrence, 66047, USA.
Joklik, Wolfgang K., Ph.D, Hilda P. Willett, Ph.D, and D. Bernard Amos, M.D,
eds. Zinsser Microbiology. 17th ed. New York: Appleton Century Crofts, 1980.
Print.
Journal of Virological Methods 82 (1999) 19–26 Detection of adenovirus using PCR
and
molecular beacon Saibal K. Poddar * Department of Pediatrics, DiTision of
Infectious
Diseases and Pediatric Pharmacology Research Unit (PPRU), UniTersity of
California
at San Diego, La Jolla, CA 92093-0808, USA Received 6 January 1999;
received in
revised form 28 April 1999; accepted 28 April 1999
Lennette, Edwin H., ed. Manual of Clinical Microbiology. 3rd ed. Washington DC:
American Society for Microbiology, 1980. Print.
Murray, P. R., K. S. Rosenthal, and M. A. Pfaller. Medical Microbiology. 6th. 18.
Philidelphia, PA: Mosby Elsevier, 2009. Print.
"Pathogenesis of Adenovirus Infection." Pathogenesis of Adenovirus Infection. N.p.,
n.d.
Web.
25 Oct. 2012. <http://virology-online.com/viruses/Adenoviruses2.htm>.
"Pharyngoconjunctival Fever ." Pharyngoconjunctival Fever. N.p., n.d. Web. 25 Oct.
2012.
<http://emedicine.medscape.com/article/1192323-overview>.
Stability of Viral Pathogens in the Laboratory Environment Hector N. Valtierra San
Diego
Community College District, San Diego, California
"The Adenovirus Family." Stanford University. N.p., n.d. Web. 26 Oct. 2012.
<http://www.stanford.edu/group/virus/adeno/adeno.html>.
"ViralZone: Adenoviridae." ViralZone: Adenoviridae. N.p., n.d. Web. 25 Oct. 2012.
<http://viralzone.expasy.org/viralzone/all_by_species/4.html>.