Wendy Vuong Joseph Martin del Campo Reza Parhizkar Micro
401
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What is RSV? Common name: cold Specific name: RSV Infection
Targets Everyone Mostly, infants (by 2 years of age) Dangerous for
Premature infants, children with heart/lung problems, elderly,
those with weak immune system.
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History First isolated from a chimpanzee (1956) localized to
respiratory tract Virus has large enveloped virion that is easily
inactivated by dryness and acid Host range is limited to
humans
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CASE STUDY A 13-month-old child had a runny nose, mild cough,
and low-grade fever for several days. The cough got worse and
sounded like "barking." The child made a wheezing sound when
agitated. The child appeared well except for the cough. A lateral
radiograph of the neck showed a subglottic narrowing.
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Negative sense, single-stranded RNA virus Belong to the
Paramyxoviridae which which consist of three genera: Paramyxovirus:
Parainfluenza and Mumps viruses. Pneumovirus: Respiratory syncytial
virus. Morbillivirus: Measles virus. RSV has the average size of
150-300nm, encodes at least 10 proteins (7-8 structural and 2
nonstructural proteins). The RNA is surrounded by a helical
nucleocapsid. Account for a large percentage of pediatric
respiratory infections. Global annual infection rates of 64 million
and mortality of 160,000 for children under the age of two.
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Case study Questions 1. What is the specific and common name
for these symptoms? 2. What other agents would cause a similar
clinical presentation?
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Coryza Symptoms of a common head cold nasal congestion
Rhinorrhea (runny nose) Sore throat Mild cough Inflammation of
nasal cavity mucous membrane, affecting upper respiratory tract (
larynx, nasal cavity, Trachea). Croup (Laryngotracheobronchitis)
Inflammation of the larynx and upper airway Results in narrowing of
the airway Characterized by a barking cough, inspiratory stridor,
and a variable amount of respiratory distress that develops over a
brief period. Stridor A high pitched, breathing sound caused by
turbulent flow of air, usually caused by a blockage in
breathing
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Intercostal retractions Are the inward movements of the muscles
between the ribs as a result of reduced pressure in the chest
cavity. The movement is usually a sign of difficulty breathing.
Common causes: Bronchiolitis is swelling and mucus buildup in the
smallest air passages in the lower respiratory system
(bronchioles), usually due to infection by RSV. Subglottic
Stenosis: Subglottic stenosis (SGS) is a narrowing of the
subglottic airway, subglottic airway is the narrowest area of the
airway and small amount of edema will significantly restrict
airflow.
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Other Agents Viruses from the Paramyxoviridae family Mumps,
measles, Parainfluenza Can also cause sporadic cases of croup
Adenovirus Infection of the respiratory tract, as well as eyes,
intestines, and urinary tract Pneumonia Inflammation of the lungs
caused by bacteria, viruses, or other microorganisms Leading cause
of death in children worldwide Influenza A and B Both caused by
viruses in the family Orthomyxoviridae
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Testing Rapid antigen test By nasal aspirate By nasopharyngeal
(NP) swab Detected by RT-PCR techniques
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Ribavirin, a guanosine analogue, severe course (e.g., premature
or immunocompromised infants) administered by inhalation Passive
immunization with anti-RSV immunoglobulin premature infants.
Infected children Infected children must be isolated. Control
measures are required for hospital To avoid transmitting measures
include hand washing, wearing gowns, goggles, and masks
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Transmission RSV is easily transmitted through aerosols,
fomites or direct contact Inhalation of large droplet aerosols that
contain RSV Direct contact from touching contaminated surfaces
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Transmitted From What? RSV is most likely introduced into
families by children in school undergoing reinfection. Also can be
introduced in hospitals or urban centers where adults also spread
the infection. Depends on the opportunity of exposure. Severity of
illness relies on the age and immune status of the host. More
severe in young infants due to immune system underdeveloped.
Initially the infection is contracted to by mucosal epithelial
cells of the nose, eyes, and mouth. Infection can then either be
confined to the upper respiratory tract or move to lower
respiratory tract meaning more severe symptoms.
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Contagion Period RSV is highly contagious from the point of
infection and is shed in respiratory secretions such as breathing,
sneezing, or coughing. Incubation period is about 4 5 days.
Contagion period precedes symptoms and may occur in absence of
symptoms. Within 10 to 24h after infection, projections of viral
proteins appear on the cell surface and bud off the cell membrane.
Greatest virus shedding in the first 4 to 5 days after onset of
symptoms. Infectious respiratory secretions can last from 5 days to
up to 3 weeks.
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CS Questions What is the specific and common name for these
symptoms? What other agents would cause a similar clinical
presentation (differential diagnosis)? Are there readily available
laboratory tests to confirm this diagnosis? If so, what are they?
Was there a possible treatment for this child? When was this child
contagious, and how was the virus transmitted?
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References 1. Centers for Disease Control and Prevention.
Respiratory Syncytial Virus Infection (RSV). Updated: Mar. 31,
2010. Access: Oct. 18, 2012.
http://www.cdc.gov/rsv/about/index.html 2. Krilov, Leonard R.
Respiratory Syncytial Virus Infection. Background. Updated: Sep 20,
2012. Access: Oct. 18, 2012.
http://emedicine.medscape.com/article/971488-overview 3.
MedlinePlus. Respiratory syncytial virus (RSV). Updated: Feb 17,
2011. Access: Oct. 18, 2012.
http://www.nlm.nih.gov/medlineplus/ency/article/001564.htm 4.
Meridian Bioscience. Testing for Respiratory Syncytial (RSV).
Access: Oct. 18, 2012. http://www.meridianbioscience.com/disease-
information/rsv/testing.aspx 5. National Institute of Allergy and
Infectioious Diseases. Respriatory Syncytial Virus (RSV). Updated:
Sept 27, 2012. Access: Oct. 18, 2012.
http://www.niaid.nih.gov/topics/rsv/understanding/Pages/cause.aspx