26/27 Viral Respiratory Tract infections Flashcards
most URT caused by baceteria or viruses
viruses
- rhinitis (inflammation of nasal mucosa)
- pharyngitis (sore throat)
- No high fever, LRT involvement or respiratory distress
common cold
what are the complications of the common cold?
- otitis media
- sinus infections
- exacerbation of asthma
what is the most common cause of cold? second most?
- rhinovirus
2. coronavirus
describe rhinoviruses
- picornavirus family
- non-enveloped
- +ssRNA genome
how are rhinoviruses spread?
respiratory secretions
treating rhinoviruses?
conservatively
-no vaccine or prescription
describe coronaviruses
- enveloped
- +ssRNA genome
treating coronaviruses?
conservatively
-no vaccine or prescription
describe adenoviruses?
- non-enveloped
- dsDNA genome
- icosahedral capsid
only common cold virus with a DNA genome?
adenovirus
which adneovirus serotypes cause URT disease/ common cold?
1, 2, and 5
no seasonal pattern to this common cold
adenovirus - ppl can shed the virus for up to 18 m.
which adenovirus serotypes cause GI disease?
40 and 41
what other illnesses are associated with adneoviruses besides common cold?
- conjunctivits
- pharyngitis
- fever
- croup
- bronchiolitis
- pneumonia
adenovirus treatment?
live oral vaccine to serotypes 4 and 7 only for military recruits
describe coxsackievirus
- enterovirus (subfam of picornavirus)
- nonenveloped
- +ssRNA genome
- able to survive GI tract
transmission of coxsackievirus
- transmitted through the fecal oral route
coxsackievirus treatment
no vaccine available
herpangina caused by…
- caused by coxsackievirus
abrupt onset of fever
small vesicles on the soft palate which form small white ulcers
herpangina caused by coxsackievirus
hand-foot-mouth disease caused by
coxsackievirus
- fever
- vesicular lesions on the palms of hand and soles of feet and on oral areas
hand foot and mouth disease
which influenza viruses are associated with the common cold
influenza viruses B and C
common cold viruses (7)
- rhinovirus
- coronavirus
- adenovirus
- coxsackievirus
- influenza B and C
- RSV
- parainfluenza virus
what is croup?
laryngotracheobronchitis
- brassy “seal’s bark” cough
- inspiratory stridor
- “steeple’s sign” narrowing of air shadow in trachea
croup
complication of croup
hypoxia
treatment of croup with stridor at rest
oxygen
epinephrine
glucocorticoids
treatment of croup without stridor at rest
humidified air
hydration
etiology of croup
parainfluenza virus
- most often type 1
what other viruses may cause croup besides parainfluenza?
RSV
measles virus
describe the parainfluenza virus
- -ssRNA genome
- helical nucleocapisd
- contains hemagglutinin adn neuraminidase
- paramyxovirus family
- myalgia
- headache
- fever
- shaking chills
- cough peaking 3-5 days
- weakness lasting weeks
influenza
peaks during the winter months
influenza
groups at risk for complications due to influenza
- younger than 2
- over 65
- pregnant and up to 2 wks postpartum
- certain medical conditions: asthma, diabetes, etc…
define pneumonia
inflammation of lung parenchyma leading to abnornal gas exchange
fever, chills, cough, chest pain, increased respiratory rate, wheezes and crackles
pneumonia
shows up as opacity on chest xray
primary influenza virus pneumonia etiology
influenza A
pneumonia 1-4 days following flu symptoms/ chest radiograph bilateral, midlung, lower lung infiltration
primary influenza virus pneumonia
biphasic (flu then return of symptoms later), gram stain may contain bacteria
bacterial influenza-associtated pneumonia
etiology of bacterial influenza-associated pneumonia
- s. pneumoniae
- s. aureus and h. influenzae
others: n. meningitidis, other streptococcus, and gram negative bacillus
describe the influenza virus
- orthomyxovirus
- segmented, ssRNA virus genome
- enveloped with hemagglutinin (H) and neuraminidase (N)
hemagglutinin (H)
- used for attachment protein
- agglutinates RBC
neuraminidase (N)
- cleaves sialic acid
- virion release and spread
small changes in H and N
antigenic drift
- driven by point mutations made by PCR during replication
large changes in H and N
antigenic shift
- driven by reassortment of two viruses
co-infection of the same cell and risk for pandemics
antigenic shift
classic method of production of vaccines..
production in embryonated chicken eggs
advantages of novel method of vaccine production
- rapid scale up of vaccine production
2. reduced likelihood of egg protein carryover
advantages of baculovirus expression vector system production
- rapid scale up of vaccine production
2. egg-free system
what is chemoprophylaxis?
daily dose of anti-viral for duration of flu season in the community
describe the SARS coronavirus
- enveloped
- +ssRNA genome
- more resistant to environmental conditions than non-SARS coronavirus
- fever, malaise, and myalgia
- dry cough and shortness of breath
- severe: adult respiratory distress syndrome and death
SARS coronavirus
transmission of SARS coronavirus
fecal-oral, close contact and aerosal routes
expiratory wheezing/ nasal flaring/ air trapping/ subcostal retractions/ variable fever
bronchiolitis
most common cause of bronchiollitis and pneumonia in children less than 1 year old
RSV
describe RSV
- paramyxovirus family
- enveloped
- -ssRNA genome
- highly infectious
nearly all children have been infected by age 4
RSV
aerosilized ribavirin treatment
for severe LRT RSV infections
mechanism of aerosolized ribavirin treatment for bronchiolitis
inhbits nucleotide biosynthesis and mRNA capping and promotes hypermutation of the genome
Indications fro passive RSV immunoprophylaxis
- birth less than 32 weeks gestation
- age less than 2 years and therapy for chronic lung disease within 5 months preveding RSV season
what are the agents for RSV passive immunoprophylaxis
- palivizumab
- RSIG
palivizumab
chimeric humanmouse monoclonal anti-RSV antibody
RSIG
pooled human immunogobin enriched for antiRSV antibodies
