Transcript Respiratory Syncytial Virus Bronchiolitis in Infants

Respiratory Syncytial Virus
Bronchiolitis in Infants
Amanda Snodgrass
Dr. Bill Grimes, Advisor
Spring 2006
Objectives
Mechanisms involved in RSV
infection and severity
 Risk factors for severe RSV
infection
 Prophylaxis and treatment of
RSV
 Morbidity and Mortality
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Case Study
RSV Facts
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Most common cause
of bronchiolitis &
pneumonia in children
under 1
25-40% of children
develop bronchiolitis
or pneumonia during
first RSV infection
31/1,000 under 1 yr.
are hospitalized with
RSV
2% will die
Presentation
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Cold-like sx
Audible wheezing
SOB
Anorexia
Poor sleeping
Irritability
Vomiting
Choking
Pathophysiology
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Negative-strand RNA virus
Family Paramyxoviridae
RSV season late fall to early spring
Peak in January/February
Incubation 4-5 days, LRI between
days 5-7
Severity of RSV Infection is
Determined By:
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Inhibition of certain interferons
Involvement of innate immune
system
Interleukins and chemokines
Coinfection with other respiratory
viruses
Inhibition of Interferons
Interferons believed to have
antiviral properties
 NS1 & NS2 inhibit IFNalpha/beta
 Inhibition of IFN-gamma causes
enhanced IgE production
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Innate Immune System
Activation contributes to
inflammation & injury
 RSV-F glycoprotein may inhibit
T-cell activation
 RSV-infected CD8+ cells unable
to release IFN-gamma
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Interleukins & Chemokines
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Infection induces expression
Chemokines mimic RSV
glycoproteins
Recruit monocytes, eosinophils, &
neutrophils
IL-8 levels positively associated with
severity
Coinfection
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Rhinovirus contributes to increased
severity in children with
bronchiolitis
Metapneumovirus (hMPV) enhances
or mimics symptoms of RSV
bronchiolitis
70% were coinfected w/ hMPV &
required amission to PICU
Risk Factors
Premature Birth
Likely to have chronic lung
disease
 Hypersensitive to stimuli
 Underdeveloped airway &
immunity
 Lack adult maternal levels of IgG
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CHD
Are more often hospitalized
 Are more often admitted to PICU
 Are more likely to die
 Complications from pulmonary
hypertension and increased
hypoxia
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Environmental & Demographics
 Male
infants
 Age & birth month of infant
 Crowding & day care
attendance
 Secondhand smoke
Factors NOT Positively Correlated
 Socioeconomic
status
 Malnourishment
 Breastfeeding
Prophylaxis
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RSV-IGIV (RespiGam)
Children under 24 mo. w/ CHD or
less than 35 wks. Gestation
Given IV monthly during RSV
season
Volume overload possible
Not for infants w/ hemodynamically
significant heart disease.
Prophylaxis
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Palivizumab (Synagis)
Given IM monthly
Can reduce hospitalization of high
risk infants by 45%
Expensive
Many providers reluctant to give
Many parents unaware
Treatment
Mostly symptomatic
 Salbutamol MDI drug of choice
 Also use epinephrine,
ipratropium bromide, & oral
steroids only if hospitalized
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Morbidity & Mortality
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More likely to visit a specialist
More likely to use respiratory
therapy
More likely to receive diagnostic or
therapeutic procedures
More likely to be hospitalized again
Subsequent hospitalization will be
3x as long
Morbidity & Mortality
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More likely to suffer recurrent
infections
Many have recurrent acute otitis
media
Many likely to be hospitalized with
another episode of acute respiratory
distress
Morbidity & Mortality
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Adolescents suffer from allergic
asthma, allergic rhinoconjunctivitis,
& more sensitive to inhaled
allergens
More likely to have asthma,
bronchial reactivity to methacholine,
and reduced lung function
RSV ind. risk factor for reduced
FEV% (FEV1/FVC)
Follow Up
References
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