Paramyxoviuses (parainfluenza and respiratory syncytial virus Flashcards
introduction to paramyxoviruses
causes respiratory inf in infants and children
measles and mumps-most contagious disease of children
per year 4 million children under 5 dies from respiratory inf and pneumonia
paramyxoviruses resembles orhomyxoviruses except that para is not segmented and no genetic reassortment (stable)
nucleocapsid is surrounded by lipid envelope
M1, HA, NA are present
pathogenesis of parainfluenza?
- parainfluenza replication occurs in the respiratory epithelia
- viremia is uncommon
- incubation period- 3-6days
- inf involves only nose and treat (harmless common cold)
- inf may be more extensive with type 1&2 parainfluenza leading to larynx and upper trachea p called croup (laryngotracheobronchitis)
croup is the respiratory obstruction due to swelling of the larynx and related structures.
-inf may be deeper to the lower trachea and for pneumonia or bronchiolitis due to type 3 parainfluenza
virus shedding for 1 week, may be prolonged in children
-production of igE during primary inf leads to severity of inf
clinical findings of parainfluenza
-primary inf- rhinitis, bronchitis, pharyngitis, fever
-serious illness- laryngotracheitis
type 1&2 croup (occurs in older children 6-18m)
pneumonia type 3 (occur in children under 6m)
otitis media- most common inf of
parainfluenza
igA antibodies are secreted in nasal secretion and are resistant to reinfection.
treatment/prevention of parainfluenza
Ribavirin, subunit vaccine&live attenuated type 3 virus(intranasally)
precautions
restrict the visitors
isolate the patient
downing by medical people
hand washing
epidemiology
type 1- winter
type3- summer
epidemiology
type 1- winter
type3- summer
Respiratory Syncytial Virus (RSV)
most important cause of lower respiratory tract inf
in infants and young children especially bronchiolitis & pneumonia.
25% of pediatric hospitalization is due to respiratory disease
pathogenesis & pathology
RSV replication occurs in epithelial cells of the nasopharynx
The incubation period btw exposure and illness is 3-5days
virus shedding may occur for 1-3weeks from infant and young children
in adult 1-2days only
virus may spread and causes bronchiolitis & pneumonia
-The lymphocyte migration result it peribronchiolar infiltration
-submucosa becomes edematous and plugs consist of
mucus, cellular debris, fibrin occlude the smaller bronchioles.
clinical finding of RSV
inapparent inf
common cold
pneumonia
bronchiolitis (distinct clinical syndrome of RSV)
1/3 of RSV involves LRT
child suffering from RSV bronchiolitis & pneumonia often show wheezing illness
2% requires hospitalization
reinfection is common
inf in elderly may cause symptoms similar to influenza virus disease.
pneumonia may develop
RSV causes otitis media (30-50% in winter time)
immunity of RSV
maternal antibodies are effective
if maternal ab falls the severity is high in the baby
RSV is not an inducer of interferon (para.i $ i are effective)
serum igG & secretory ab (igA) are important
lab diagnosis of RSV
RSV has no hemagglutinin
isolation of virus and detection of antigen are choice of diagnosis
virus culture in human heteroploid cell lines are most sensitive for viral isolation.
development of giant cells & syncytia
Epidemiology of RSV
a major pediatric RT pathogen
spread by large droplet/ direct contact
70% of infant of age 1-2 yrs are infected
bronchiolitis/pneumonia mostly occurs btw age 6w-6m
RSV- most common cause of viral pneumonia in children.
treatment of RSV
supportive care- removal o secretion
administration of oxygen
RIBAVIRIN is for LRT disease (administered in an aerosol for 3-6 days)
oral ribavirin is not useful/ no vaccination
passive immunoglobulin is somewhat good
