Influenza Flashcards
Type of influenza predominantly infecting humans
Influenza A and B
Type of influenza responsible for pandemic outbreaks
influenza A
Type of envelope protein responsible for entry of virus into cells and serves as viral attachment protein
Hemagglutin (HA) - surface antigen where antibodies are directed
facilitate CELL-to-CELL spread of virus and the target for the antiviral drugs zanamivir and oseltamivir
Neuraminidase (NA)
It is a structural protein integral to the INFECTIVITY of influenza and LINKING viral envelope with the core
Matrix proteins M1 and M2
replacement of Introduction of new HA resulting into pandemic; influenza A
Antigenic shift
mutations within the antibody-binding sites in HA, NA, or both; prevent antibodies against previous strains from being effective
ANTIGENIC DRIFT (both A and B)
Incubation period
2-3 days (18 hours to 5 days or more)
can be as rapid as 18 hours
or as long as 5 or more days
Young children shed ____ days or longer with generally higher viral titers.
10 days (vs adults 3-7 days)
Influenza responsible for _____& of URTI in children.
5%–15%
Individuals at high risk for influenza complication
Less than 2 yrs of age, Less than 19 yo on aspirin, >65 yo, morbidly obese BMI >40, all ages with comorbids
apoptosis of the infected epithelial cells will lead to
acute tracheobronchitis
Pathogenesis of influenza virus
attachment of viral HA to terminal sialic acids –> receptor-mediated endocytosis –> viral M2 forms ion channels -> Liberated viral RNA –> (mRNA) and viral RNA are synthesized –> budding of daughter virions –>NA facilitates virion release
type I AECs are damaged leading to
acute alveolar damage –> ARDS
**tight junctions of the alveolar capillary membrane allow a transudate of fluid and proteins to enter the alveolar spaces
Increased risk of secondary bacterial infection due to
delayed epithelial healing
predisposes the host to allergic airway inflammation and asthma
TSLP stimulating dendritic cells to induce Th2 cells
promoters of eosinophilic inflammation, excessive mucus secretion, and bronchial hyperresponsiveness
IL 25 and IL-33 (stimulates ILC2 to synthesize IL-5 and IL-13
the best predictors of influenza infections
cough and fever
young children presents with
o less classic presentation
o have higher fevers
o less prominent respiratory symptoms
o more GI symptoms such as abdominal pain, vomiting, diarrhea
Rash is an uncommon but when it occurs it is usually
generalized maculopapular rash sparing the palms and soles.
PE findings of influenza
- tachypnea
- conjunctival erythema
- nasal injection
- edema
- nasal discharge
- cervical adenopathy
Most common radiographic finding
bilateral, symmetric, perihilar, and peribronchial opacities
severe influenza
ARDS
the most common pathogen identified in influenza
Strep pneumoniae
