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Respiratory Syncytial Virus Concerns and Control

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Respiratory Syncytial Virus Concerns and Control Pediatrics in Review Vol. 24 No. 9 Sept. 2003 Respiratory Syncytial Virus : Introduction Virology Epidemiology ... – PowerPoint PPT presentation

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Title: Respiratory Syncytial Virus Concerns and Control


1
Respiratory Syncytial Virus Concerns and
Control
  • Pediatrics in Review Vol. 24 No. 9
  • Sept. 2003

2
Respiratory Syncytial Virus
  • Introduction
  • Virology
  • Epidemiology
  • Pathogenesis Immunity
  • Complications Long term Effects
  • Diagnosis
  • Therapy Prevention

3
RSV Introduction
  • RSV is responsible for outbreaks of lower
    respiratory tract disease in young children.
  • Bronchiolitis pneumonia from RSV are frequent
    causes of hospitalization.
  • Recent conformation of the significance of RSV in
    causing respiratory tract illness throughout
    life.
  • Therapy prevention based on increased
    understanding of the virus host response .
  • Control of RSV infection.

4
RSV Virology
  • RSV Paramyxovirus, pneumovirus.
  • RSV chimpanzee coryza agent.
  • RSV Isolated from infants with respiratory
    symptoms , renamed because of its characteristic
    syncytial pattern.
  • Enveloped virus, -ve single stranded RNA genome
  • Genome codes for 10 m RNAs, each codes for a
    specific protein.
  • Viral envelop F, G ,SH, M ,M2
  • Neucleocapsid L, N, P
  • NS1, NS2

5
RSV Virology
  • Two major groups A B
  • PH 7.5, Temperature sensitive.
  • Stable in hospital environment recovered
  • from countertops rubber gloves.
  • Nosocomial Pathogen

6
RSV Epedemiology
  • Present world wide, yearly epidemics.
  • Appears in Nov. or Dec. persists till Apr. or
    May.
  • A strain predominant , the two strains circulate.
  • Strain variation does not significantly affect
    the clinical severity.
  • Peak incidence 2-5 months.

7
RSV Epidemiology
  • In the 1st two years of life one or more RSV
    infections
  • More severe Boys , lower socioeconomic classes.
  • Reinfection throughout life is common.
  • Milder than primary infection.

8
RSV Pathogenesis Immunity
  • Incubation period 2-8 days.
  • Ocular, nasal contact with infected secretions.
  • Upper airway cough rhinorrhea.
  • 50 primary infection spreads to lower tract.
  • Bronchiolitis lymphocyte infiltrate epithelial
    proliferation.
  • Obstruction mucus epithelium .
  • Hyperinflation.
  • Interstitial infiltrates Pneumonia.

9
RSV Immunity
  • Immune response not well understood.
  • Different parts of immune system are involved.
  • Antibodies
  • Higher levels of maternal Abs , lower infection
    rates.
  • Prophylactic Abs reduce but do not eliminate
    severe disease.
  • No level of serum Abs provides protection.
  • Type of Ab generated may be critical.

10
RSV Immunity
  • Cell mediated immunity
  • Integral in clearance recovery.
  • T- cell deficiency severe infection prolonged
    shedding.
  • Type of T-cell response influences control.
  • Type extent of cytokine production determines
    response to RSV.

11
RSVClinical Features
  • Wide range of illness , rarely asymptomatic.
  • Illness begins cough , nasal congestion
    fever.
  • Ottitis Media
  • LRT disease 50
  • LRT disease tachypnea , dyspnea, retractions.
  • Feeding difficulty, hypoxemia.

12
RSV Clinical Manifestations
  • LRT disease
  • Bronchiolitis VS. Pneumonia
  • Bronchiolitis Pneumonia
  • Overwhelming Sepsis
  • Young infants
  • Apnea
  • Preterm infants
  • Croup
  • Fewer than 10

13
RSV Clinical manifestations
  • High risk infants
  • Preterm infants
  • Chronic lung disease
  • Congenital Heart disease
  • Immunocompromised
  • Neurological disorders
  • Multiple congenital Anomalies.

14
RSV Clinical manifestations Children Adults
  • Repeated Infections milder , localized to URT.
  • LRTI uncommon, may be followed by airway
    hyperactivity.
  • Immunocompromised BMT severe , fatal disease
  • URT symptoms suspect RSV
  • Early therapeutic measures.

15
Complications long term Effects
  • Acute
  • Respiratory Failure
  • Apnea
  • Secondary bacterial infection
  • Long Term Effects
  • Reactive Airway Disease??

16
Diagnosis
  • Young Children
  • Season
  • Typical history
  • Physical examination
  • Children Adults
  • Signs Symptoms are less specific.
  • Chest x ray nonspecific
  • Chest X rays
  • Hyperinflation
  • Peribronchial thickening
  • Increased interstitial markings
  • Consolidation, Atelectasis

17
RSV Diagnosis
  • In children with mild disease, definitive
    diagnosis may not be necessary.
  • In hospitalized patients those with severe
    disease ,an accurate diagnosis may limit further
    lab. evaluation and antibiotic use.
  • RSV may be identified by viral isolation or by
    one of numerous rapid assays.

18
RSV Diagnosiscont.
  • Infants
  • Nasal wash
  • Children adults
  • Swab from nasal turbinatespharynx
  • or bronchoalveolar lavage are the most likely to
    be positive Specimens obtained by endotracheal
    tube
  • Specimens for culture should be placed in viral
    culture media kept cold during transport.
  • RSV grows in multiple cell lines ( Hep-2 HeLa)
  • Typical pattern syncytial giant cell , 3-7
  • Fluorescein-labled Ab are applied to cultures.

19
RSV Diagnosis
  • Rapid assays
  • Fluorescent antibody tests
  • Enzyme immunoassays
  • Reverse transcriptase PCR
  • Tissue Biopsies
  • Serologic testing for RSV is not useful for
    management
  • Has been used in epidemiological studies.
  • Difficult to interpret in the very young
    immunocompromised

20
RSV Therapy
  • RSV therapy remains largely supportive
  • Supplemental oxygen, IV fluids
  • Bronchodilators??
  • Corticosteroids??
  • Vitamin A??

21
RSV Ribavirin
  • Ribavirin the only antiviral agent currently
    licensed for treatment of RSV infection.
  • It is a synthetic nucleoside analog that
    interferes with expression of mRNA prtn
    synthesis.
  • Nebulized Ribavirin is associated with clinical
    improvement,but a decrease in hospital stay has
    not been documented.
  • Efficacy vs. Cost
  • Toxicity adverse reactions
  • Ventilated patients

22
RSV Therapy Ribavirin
  • AAP Decisions regarding Ribavirin therapy are
    to be based on individual clinical situation
    physicians experience
  • Ribavirin is licensed for treatment by aerosol
    route by O2 hood, tent or mask until
    improvement.
  • Usually 3-7 days, or longer in severe cases.
  • No guidelines regarding administration to adults

23
RSV Therapy Others
  • IV inhaled Igs have bee used in small numbers
    but with no significant benefit.
  • Immunocompromised patients , in combination with
    Ribavirin.
  • Other Agents
  • IM alpha 2a interferon
  • Surfactant
  • Rh-DNA ase
  • Drugs affecting cytokine production alone or with
    others
  • New Antiviral agents

24
Infection control Procedures During RSV season
  • Educate hospital staff patients families about
    RSV.
  • Emphasize maintain good hand washing
    procedures.
  • Use contact isolation for patients with RSV.
  • Cohort children RSV infection.
  • Identify RSV by using rapid accurate assays.
  • Use mask for staff who have respiratory symptoms.

25
Infection Control
  • Cohort staff , if possible , to infected
    uninfected patients
  • Limit visitors during RSV season.
  • Postpone elective admissions for high risk
    patients in RSV season.
  • Identify uninfected infants who may benefit from
    immunoprophylaxis..

26
RSV Prevention
  • Prophylactic Antibodies to RSV has been shown to
    decrease severe disease.
  • Two products have been approved for use in
    selected children at high risk for RSV.
  • Neither product currently is licensed for use in
    infants with cyanotic congenital heart disease.
  • Prophylaxis may be beneficial in
    Immunocompromised children.
  • Expenses of prophylaxis.
  • Regional analysis is required.
  • Impact on long term complications is yet unknown.

27
RSV Prevention RSV IGIV
  • Approved in 1996, after multicenter PREVENT
    trial.
  • Patients received monthly infusions of RSV-IVIG,
    or placebo during RSV season.
  • Those receiving RSV-IVIG had a 41 reduction in
    rate of hospitalization,fewer hospital days
    less frequent O2 requirements.

28
RSV Prevention Palivizumab
  • It is a humanized IgG-1 monoclonal Ab, that binds
    to the F prtn of RSV.
  • It is estimated to have 50 - 100X more activity
    than RSV IGIV.
  • Given IM.
  • Approved in 1998 after placebo controlled
    multicenter trial ( Impact Study)
  • Administration resulted in 55 reduction in
    hospitalizations.
  • RSV IVIG vs. Palivizumab.

29
AAP Recommendations for prophylaxis
  • Childrenlt 2yeras ,chronic lung disease received
    medical therapy in the last 6 months.
  • Infants lt 32 wks gestation
  • lt 28 wks
  • 32 gt age gt 28
  • 35gt age gt32

30
RSV prevention Vaccines
  • Development of an effective vaccine remains a
    challenge.
  • A variety of approaches to Vaccine development
    have been studied.
  • Types of candidate vaccines include inactivated
    ,live attenuated subunit vaccines.
  • Successful immunization against RSV may require
    different individualized approaches.
  • Maternal immunization may be protective , but not
    for LBW infants

31
RSV prevention
  • Additional strategies are needed to provide
    protection shortly after birth.
  • In older individuals vaccines that the existing
    to RSV maybe beneficial or more feasible to
    develop.
  • Possible therapeutic preventive measures are
    evolving rapidly, portending that the burden of
    RSV disease soon may be lessened.
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